Sun Solar Cooking: Fail-Proof, Guaranteed Solar Cooking Strategies 9781483570648

Citation preview

ISBN: 978-1-483-57064-8

DISCLAIMER

 

Although the contents of this eBook are based on factual research, anecdotal evidence and personal experience, Lee Elliott cannot be held accountable for the manner in which you decide to use the information supplied in this eBook.

  The author and publisher have made every effort to make this eBook as comprehensive and accurate as possible, with the content in the eBook based on verifiable research and established facts, and as such they assume no responsibility for errors or omissions.

  There may be mistakes both typographical and in content. No guarantee is provided in the eBook that the information stated is correct, complete and current. Therefore, the content should be used only as general guide and not as a specific or generic source of the subject matters covered.

  You should be circumspect in using this information, and understand this is at your own risk. Your unique situation may not be perfectly aligned to the circumstances demonstrated here, and you should adapt your use of the information and recommendations accordingly.

  Any trademarks, service marks, product names or named features are assumed to be the property of their respective owners, and are used only for reference. There is no implied or actual endorsement if we refer to one of these specific designs or features.

 

This eBook is in no way intended to be a substitute for any legal, medical or professional advice on the subject matter.

  Readers of this eBook are advised to conduct their own due diligence in terms of making business or purchasing decisions based on the content, and we recommend strongly that these decisions are independently verified by your own qualified professionals.

  Your level of success in attaining the results claimed in our eBook depends on the time you devote to the procedures, ideas and techniques illustrated, your knowledge and various skills. Since these factors differ according to individuals, designs and environmental and geographical circumstances, results may vary.

  Above all you need to employ common sense.

TABLE OF CONTENTS

 

Introduction

  History of Solar Ovens

  Principle of Solar Cooking

  Concentrating sunlight (angle of reflection)

  Converting light waves to heat energy

  Trapping heat

  Scaling and measurement

  How to Use a Solar Box Oven

  Solar Water Pasteurization

  SODIS (solar water disinfection)

  Solar water pastuerization using a solar cooker or equivalent device

  Solar cooker

 

Flow-Through pasteurization devices

  Solar puddle

  Solar distillation

  Different Types of Solar Cookers

  Box solar cooker

  Panel solar cooker

  Solar kettle

  Parabolic solar cooker

  Hybrid solar cooker

  Solar vacuum tube oven

  Funnel solar cooker

  Hot dog solar cooker

  Solar Cooking Pots

  Advantages of Solar Cooking

  Disadvantages of Solar Cooking

  Solar Dehydration

  How to Build a Solar Cooker

  Building a funnel solar cooker

  Building a box solar cooker

  Building a pizza box solar cooker

  Building a hot dog solar cooker

  Building a parabolic solar cooker

  Solar Cooking Organizations

  Solar Cooking Resources

  Purchase of Solar Cookers

  Solar Cooking Recipes

  Solar breads

  Solar soups

  Solar pasta

  Solar cake baking

  Solar vegetables

  Solar desserts

  Solar chicken

  Solar meat

  Solar seafood

Introduction

  As a child I was infatuated with adventure stories, in any shape or form. My heroes ranged from Asterix and Obelix, terrorizing the poor, downtrodden Romans, and in the process drinking copious volumes of wine and beer, to Tintin, his small dog Snowy and the perpetually dubious Captain Haddock, who as a team fluctuated widely, one minute scouting the dark jungles of the Amazon to the next adventure on some remote outpost on the dark side of the moon.

  Be it Nancy Drew, the Hardy Boys or Biggles, my thirst for good, adrenaline-pumping adventure stores remained insatiable. One character who in particular remained a constant source of fascination to me was the indomitable Huckleberry Finn. Maybe it was the curious company he kept, from his lifetime friend Tom Sawyer, to his new-found, surreptitious companion Jim, the runaway slave, or just the assortment of odd people who constantly popped in and out of his life. Either way, in my mind’s eye, I could easily visualize him travelling down the swollen Mississippi River on his raft, contemplating life or at the very least seemingly being able to effortlessly live constantly in the moment, like some loyal cinematic addict glued to the screen of a giant, continuous cinema theater churning out one new movie after the next. Huckleberry Finn moreover was always a participant, never a displaced observer.

  In retrospect probably the only thing that surprises me about Huck is that he seemingly never possessed a solar cooker. I would have naturally just assumed that he would have one, no doubt manufactured at great length and with loving, detailed care, from raw materials undoubtedly bartered

for various catfish that he and Tom had pursued and caught with great vigor and excitement on the banks of the Mississippi.

  I can just imagine Tom and Huck catching and skinning catfish, and with gay abandon tossing these huge fish over their shoulders and trudging nonchalantly up to the regular Trading Store to barter and procure the necessary material for the solar cooker. After all what better way to end one their many frenetic days than eating a well-cooked solar meal out of their solar cooker, from the deck of their raft, of course!

  Whist I do not profess to know if Huckleberry Finn ever owned a solar cooker or not, what does continue to surprise me is how long is has taken society to catch on to the concept of renewable energy, be it solar, wind, tidal, geothermal or microbiological. Even more surprising is the level of reluctance displayed by this same society as a whole, to make this next leap of faith.

  Remarkable as it seems, Thomas Edison almost 80 years ago, in 1931, was quoted (in Uncommon Friends: Life with Thomas Edison, Henry Ford, Harvey Firestone, Alexis Carrel & Charles Lindbergh (1987) by James Newton, p. 31), as saying in conversation with Henry Ford and Harvey are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature’s inexhaustible sources of energy – sun, wind and tide…. I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle

  Historical scenes playing out on CNN of ballooning rivers of crude oil gushing out from damaged oil wells in the Gulf of Mexico tend to reinforce the growing collective perception that fossil fuel energy not only

remains unpalatable to the average man and woman on the street, but also simply has a life span. Apart from being ultimately damaging to the environment, as a long-term sustainable solution it is simply morally corrupt.

  Fortunately it seems this perception is shared by some fairly influential people and in this regard on June 15 2010 President Barak Obama in his address to the American people said, amongst many other things, that…

  decades we have known the days of cheap and easily accessible oil were numbered. For decades, we’ve talked and talked about the need to end America’s century-long addiction to fossil fuels. And for decades, we have failed to act with the sense of urgency that this challenge requires. Time and time again, the path forward has been blocked-not only by oil industry lobbyists, but also by a lack of political courage and

  President Obama was talking conceptually of course but his call to action was unmistakable. He of all people must stand firm against this recalcitrance. Having said that, one at last begins to sense an approaching watershed and with it, hopefully, a change of thinking.

  To what degree solar energy will contribute to future endeavors to harness renewable energy remains to be seen, and no doubt it will take a long time for the average housewife to swap her digital electric or gas oven for a solar cooker, especially on overcast and rainy days.

  Coincidentally three months after President Obama’s national address, his Secretary of State, Hillary Rodham Clinton, on announcing the inauguration of the Global Alliance for Clean Cookstoves, a new public-

private partnership led by the United Nations Foundation (UNF), pronounced we can finally envision a future in which open fires and dirty stoves are replaced by clean, efficient and affordable stoves and fuels all over the world -- stoves that still cost as little as $25. By upgrading these dirty stoves, millions of lives could be saved and improved. Clean stoves could be as transformative as bed nets or

  Whilst she admittedly never articulated the concept of solar cooking what is unmistakable is that solar cookers are a prime example, arguably the best practical example, of clean cookstoves.

  Hopefully in the not too distant future, solar cooking will no longer be seen to be the exclusive domain of poor communities living in remote areas of Africa, alternatively some sort of weird, complex pastime to be pursued by passionate, wide-eyed vocal greenies. Hopefully solar cooking and solar cookers will become somewhat more visible, accepted and enjoyed by mainstream society. Hopefully.

History of Solar Ovens

  Solar ovens (solar cookers) have a rich and surprisingly early history dating right back to the exodus of the Israelites from Egypt during the reign of the Pharaoh Ramses II (1279-1212 BC), during which time the Israelites baked their breads from pre-prepared raw dough in solar ovens during their journey through the desert.

  Horace de Saussure, a French-Swiss Physicist, is often accredited with creating the first elementary solar box cooker in 1767, during which time he experimented with trapping the energy of the sun in small, openbottomed glass boxes (effectively a miniature greenhouse) placed upside down on a black table, to achieve temperatures in excess of 180 degrees Fahrenheit and as a consequence was successful in cooking fruit, .although his devices never achieved any commercial application, despite subsequent design improvements to include pine boxes, wool insulation and endeavors to cook at differing altitudes.

  In 1830 Sir John Herschell, a British astronomer, cooked food in a similar insulated hot box on an expedition to South Africa and in the latter part of the century Augustin Mouchot, a French mathematician, was the first to combine the box heat trap concept and burning mirrors to create a solar oven. He became particularly interested in the solar cooking potential in the French colonies in North Africa and Asia, where there was an abundance of daily sunlight.

  In 1877 Mouchot designed solar ovens for the French military resident in Algeria. He successfully baked bread in 3 hours and subsequently built a

separate solar oven to steam vegetables, and tried his hand at shishkabobs in a parabolic cooker. He successfully pasteurized water and wine, and researched a solar device to break down water to its constituent parts of hydrogen and oxygen.

  In 1876 in India, W. Adams developed an octagonal solar oven with an 8 mirror configuration which effectively cooked food for military personnel in less than 2 hours. In 1884 Dr. Samuel P. Langley, an American astronomer and and a recognized expert in the field of solar physics, cooked meals atop Mt. Whitney in California using a solar oven.

  Dr. Charles G. Abbot, an American who went on to become Secretary of the American Smithsonian Institution (1928-1944) , developed a solar cooker in the early 1940s in which the heat collector was outside exposed to the sun but the cooker itself was in the house, with heat transferred from collector to cooker by circulating oil. Conceptually this design allowed the heat to be stored and used to fuel the solar cooker, even when the sun had gone down.

  Solar cooking eventually began to gather some momentum shortly after the second world war, and in the 1950s Dr. Maria Telkes, a scientist at MIT, invented a solar box cooker made from insulated plywood and using a combination of layered glass and flared reflectors. She went on to publish one of the original books on solar cooking, titled Solar Ovens, in 1968.

  In March 1954 the Association for Applied Solar Energy was established and subsequently at the first conference in Phoenix, USA, various early model solar ovens went on display, including parabolic solar ovens and solar box cookers.

 

From the late 1950s through to the 1960s the UN made various attempts at broadening the appeal of solar cooking through various initiatives, although limited success was achieved and no long-term sustainable solution was realized. This includes a United Nations Conference in 1961 on New Sources of Energy, which encompassed various solar cooker experts, including Telkes, Löf, Duffie, Pruta and Abu-Hussein.

  In the 1970s the potential of the solar cooking concept was wellrecognized and both India and China became more involved at spreading the appeal, especially in light of the ever-increasing trend of deforestation, energy shortages and expanding population growth in both countries. In 1973 China hosted its first conference on solar cooking and in the early 1980s embarked on a program of distributing subsidized solar ovens.

  In the 1970s and through to the 1990s Barbara Kerr and Sherry Cole, two Arizona women, had an extremely positive influence on the solar cooking movement, starting with the design of the EcoCooker, a solar cooker built from a cardboard box. They eventually went on to design a collapsible panel solar cooker (a hybrid design between a box and parabolic solar cooker), the BackPacker, which ultimately was redesigned as the CooKit a commercially built solar oven used all over the world to this day.

  Both Kerr and Cole were also instrumental in the formation of Solar Cookers International (a non-profit, volunteer organization) in July 1987, an organization that served (and continues to serve) to network, educate, train and coordinate the solar cooking concept worldwide.

 

In their early work both women were able to clearly demonstrate that virtually all kinds of food could be cooked using the heat from the sun in relatively inexpensive solar ovens without the danger of spoiling the food and without risk of the solar cooker catching alight, despite some of the high temperature profiles achieved. They successfully used simple, recycled materials and aluminum foil.

  In 1979 the then Organization of African Unity held the 1st of 7 sessions on New, Renewable and Solar Energies, during which time the concept of solar cooking was put on the agenda with the intention being to vigorously pursue the concept throughout Africa.

  Since the 1980s the solar cooking concept has continued to be researched globally, although the relatively inexpensive cost and large-spread availability of electricity has, to some degree, slowed the advance in the first world countries.

  During 1989 at a World Conference of the World Association of Girl Guides and Girl Scouts, a delegation from Solar Cookers International presented their cardboard solar cooker. It was suggested that sunny countries such as South Africa should take up this idea and, through their members the Girl Guides, should attempt to spread the solar cooker concept.

  As an Adult Trainer within the Girl Guide Association, Margaret Bennett took up the challenge and attempted to introduce solar cooking to South Africa and the neighboring countries. Although the theory was to introduce and promote the concept in rural South Africa this approach did not really gather any impetus mainly due to a lack of easily available materials and expertise.

  This approach was abandoned and Margaret Bennett looked into designing and manufacturing the solar cookers herself. Her initial endeavor was to manufacture a kit solar box that could be sent out and assembled on site. She collaborated with some of the raw material suppliers and collectively they put in a huge amount of time and effort in perfecting the bonding of aluminum foil to heavy-duty cardboard to produce an appropriate solar oven.

  Unfortunately the material input costs of this initial model were prohibitive and Margaret Bennett experienced a lot of cost-resistance. In addition, the design itself proved to be problematic. The large reflector held up by a prop stick was a huge nuisance. It either fell flat or acted as a sail and carried the solar cooker away in the wind. It was difficult to train inexperienced users to align it properly around 2 axes, and if it wasn’t focused, it didn’t cook.

  Fortunately shortly thereafter Margaret Bennett teamed up with Dick Wareham who had worked on a similar design of solar cooker. Once they teamed up together and threw their collective effort behind the project they made swift progress. Ironically once the design issue were resolved their next biggest challenge proved to be the distribution of the Sunstove solar cooker around South Africa as they discovered that the round Sunstove solar cooker travelled poorly. The Sunstove tended to distort in transit, which became problematic.

  This problem was overcome by designing and manufacturing a mould using a blow molding process, and ultimately a robust Sunstove solar cooker emerged that would withstand rough handling during transport and actually stack together to cut costs. The current Sunstove model performs

even better than the original design, it is less complicated to manufacture, it travels well and only weights 11lbs (5kg) and costs less than $50.

  In 2009 the “new kid on the block” had to be the Kyoto Box solar cooker, designed and manufactured by Kenya-based entrepreneur Jon Bøhmer. Touted as a solar-powered cardboard cooker which aims to transform the lives of hundreds of millions of villagers in developing countries, the Kyoto Box solar cooker is the 2009 global winner of the $75,000 Financial Times Climate Change organized by the Forum for the Future, for innovation to tackle climate change.

  The Kyoto Box uses the greenhouse effect to cook and can boil 10 litres of water in two hours. It consists of two boxes, one inside the other, with an acrylic cover which lets the sun’s power in and traps it. Black paint on the inner box and silver foil on the outer help concentrate the heat, while a layer of straw or newspaper between the two provides insulation.

  Bøhmer is founder and chief executive of Kyoto Energy, a Nairobi-based design and engineering company working on novel energy solutions for the developing world. He plans to use the prize money to conduct mass trials in ten countries, including India, Indonesia, South Africa, Kenya, Uganda, Tanzania, Mozambique and Liberia.

  He has developed a more robust, longer-lasting solar cooker in corrugated plastic, which can be mass-produced in existing factories as cheaply as the cardboard solar cooker prototype, and he intends to produce 10,000 to use in the trials. The trials will generate data to back an application for carbon credits, the crucial element which will make the project scalable, he explains. He expects each solar cooker stove to make a yearly profit of 2030 euros, which will more than cover the manufacturing cost.

  Coincidentally also in 2009 the $75 000 St. Andrews Prize for the environment went to One Earth Designs (OED) for their innovative SolSource 3-in-1 lightweight, wind-resistant solar cooker designed specifically for the local Himalayan villagers. Not only is their device an excellent solar cooker (able to boil water in less than 10 minutes) but it employs additional solar synergy and functions also to generate stored thermo-electricity as well.

Principles of Solar Cooking

  There are a variety of types of solar cookers: over 10 major designs and hundreds of variations of them. Solar cooking clearly demonstrates Isaac Newton’s law of Heating and Cooling, wherein Newton proposed that the temperature of a hot object decreases at a rate proportional to the difference between itself and the surrounding temperature. Similarly, an object colder than its surroundings warms at a rate proportional to the same difference.

  In terms of the relevant formula, Newton’s laws of proportionality relation can be written as “T/”t = c (T - S), where T is the object’s temperature, S is the surrounding temperature, t is time, and c is a constant of proportionality. The change in t, “t, is small, since the law is for an instantaneous rate of change.

  Simply put the rate at which food cooks is proportional to the difference between the temperature of the food to be cooked and the temperature of the oven. In other words all things being equal, food placed in an oven at a temperature substantially higher than an identical oven with a lower temperature will cook faster.

  Ideally a solar oven should be heated in the sun prior to adding the food for this exact reason. An additional catalyst would be to heat the solar cookware and even cooking liquids (water, milk etc.) prior to cooking the meal.

  The fundamental principle of all solar ovens is that sunlight is converted to heat energy, which is retained for cooking. The individual tenets of this

principle are:

  Concentrating Sunlight (Angle of

  A reflective device, usually a mirror or some type of reflective metal, for example aluminum foil or aluminum paneling (shiny side facing outwards towards the sun), is used to concentrate light and heat from the sun, into a small cooking area, making the energy more concentrated and therefore more potent. Effectively sun rays are reflected onto the container in which the food is being cooked, thus heating the container.

  The heat generation from sunshine occurs when photons moving around within light waves, engage and interact with molecules moving around in a substance. The electromagnetic rays emitted by the sun contain excessive energy. When these rays make contact with matter, whether solid or liquid, this energy induces the molecules in that matter to vibrate. This increased vibration generates heat.

  When light is reflected off a flat shiny surface, the angle of reflection with the surface, θr, is equal to the angle of incidence, θi. Direct sunlight remains the primordial raw material for solar cooking. A solar cooker will not function at night-time or during an excessively cloudy day, with the exception of a solar kettle.

  Converting Light Wavesto Heat

  Any black on the inside of a solar cooker, as well as certain materials for pots, will improve the effectiveness of turning light into heat. A black pan or pot will absorb almost all of the sun’s light and convert it into heat, substantially improving the effectiveness of the solar cooker.

  Also, the better a pot conducts heat, the faster the solar cooker oven will work. If the cooker has a black bottom then even more heat energy will be produced, making the cooker even more effective. Dark (preferably black), shallow, thin enamel/ cast iron pots with a tight-fitting lid work best.

  Trapping Heat Thereby Retaining the Heat

  Isolating the air inside the solar cooker from the air outside the solar cooker makes an important difference. Using a clear solid, like a plastic bag or a glass cover, will allow light to enter, but once the light is absorbed by materials within the cooker, it is transformed into longer wavelength heat energy and effectively trapped by a plastic bag or glass cover.

  This makes it possible to reach similar temperatures on cold and windy days as is reached in the solar cooker on hot days. From a solar cooking perspective it is preferable to have cold, ambient temperatures, yet clear, unadulterated sunshine as opposed to warm ambient temperatures yet a cloudy, overcast day.

  The effect is amplified by ensuring that the solar cooker is adequately insulated. The heat retention effect can be further enhanced by placing adobe or bricks (preferably bricks that have been preheated) in the cooking space. These materials have a high heat capacity which keeps heat captured for long periods of time.

  Also, the thicker the pots used, the greater the amount of heat absorbed. Although this initially allows for a slower cooking rate it does promote a longer, sustainable cooking period, even after the sunlight has become diluted or the sun is in the process of setting (the thinner pots allow for a faster rate of cooking but less sustained).

 

The heat loss in a solar cooker over time is explained by the Second Law of Thermodynamics which explains the equilibrium effect of heat evening out by the movement of heat from hot to cold (temperature differences between systems in contact with each other tend to move towards equilibrium to equalize). Gradual heal loss in a solar cooker is a combination of conduction, radiation and convection.

  Alone, each of these strategies for heating something with the sun is fairly ineffective, but most solar cookers use two or all three of these strategies in combination to achieve temperatures sufficient for cooking. The top can usually be removed to allow dark pots containing food to be placed inside.

  One or more external reflectors of shiny metal or foil-lined material may be positioned to bounce extra light into the interior of the solar cooker oven chamber. Cooking containers and the inside bottom of the solar cooker should be dark-colored or black. Inside walls should be reflective to reduce radiative heat loss and bounce the light towards the pots and the dark bottom, which is in contact with the pots.

  Scaling and

  Recipes can be proportionately scaled up or down, for example a recipe for eight can be proportionately scaled down to a recipe for four or even two, and vice versa. Assuming the individual criteria can be measured, consequent cooking times and energy savings can be calculated. Similarly if the angle of incoming sun rays can be measured, then the position and panels of a solar cooker can be adjusted to maximize the angle of reflected sunlight onto the cooking utensil (assuming the angles are measured relative to a line perpendicular to the reflecting surface).

How to Use a Solar Box Oven

  Most solar box cookers are also reasonably priced, easily operated and fairly spacious, enabling you to easily cook a meal for 4-6 people in one sitting. In addition these devices have no working or moving parts, are weather resistant and literally have a propensity to last a lifetime if carefully and properly cleaned and maintained.

  This particular design of solar cooker is arguably the most popular design globally and is unquestionably one of the easiest models to build at home for the DIY enthusiasts. Excellent commercial examples of solar box cookers include the Global Sun Oven, the Sports Solar Oven and the Sunstove.

  The solar box oven is probably the most simple and most widely used solar oven. There are a number of simple sequential steps to be followed when using the box oven. Prior to the food preparation, it is advisable to pre-heat the box oven.

  Familiarize yourself with the sunlight angles, pathways and times and attempt to have the cooker fully exposed to the direct sun from onset to the termination of cooking, ensuring that there are no obstacles that will cast a shadow over the cooker at any stage. The key success factor with any solar cooking endeavor is the amount of sunshine.

  The effectiveness of solar cooking drops off rapidly with overcast weather and on a day when the conditions overhead become very overcast, little or

no solar cooking will occur. Even when the ambient temperatures plummet, for example in an environment with 2 feet of snow, as long as there is sufficient, bright sunshine the solar cooker will function adequately (it is preferable to have cold, ambient conditions and a clear sky with abundant sunshine, than a warm day but overcast and cloudy conditions).

  Place the oven in full sunlight in the direct path of the sun, preferably as early as possible. Ensure the cooker is horizontal and on level ground and the long side (face of the cooker) is centered on the sun’s east-to-west path (the sun rises in the east and sets in the west in both the southern and northern hemisphere). The heat of the sun obviously varies in different climates, but in general endeavor to position the empty box oven in full sunlight before mid-morning, with the lid on and tightly closed.

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Sunstove-horno-solar.jpg Author: Boirac

  Ensure you have the appropriate cooking utensils available (preferably black enamel bellied or cast iron pots for vegetables, meat and chicken or a black rectangular lidded pan for fish). If you have the time and patience, you can use various different types, constructions and size pots and pans using water as a control, and using a thermometer to measure the temperature of the water after a certain period of heating, to ascertain

which pot heats water the fastest and therein better understanding the various performances of the utensils.

  An appropriate pair of oven gloves is advisable as well and depending on the degree of reflection from the sun, you may also be more comfortable using sunglasses. Another heating tip is to pre-heat the solar pots in the solar cooking prior to actually adding food to the pots. Alternatively some people add a black, ceramic tile/ tiles to the bottom of the solar cooker prior to actual cooking. The tiles heat up independently and facilitate accelerated heating of the underside of the pots if the pots are placed directly on the tiles.

  Depending on how scientific you want to be in your approach, you can also go to the lengths of measuring the temperature increase in your cooker. After correctly positioning your cooker, measure the temperature after 1 hour to ensure the internal ambient temperature has reached a minimum of 220 degrees Fahrenheit (104 degrees Celsius).

  If the temperature is below this, it suggests there is either excessive convective heat loss occurring or there is insufficient exposure to the sunlight, or a combination of both. In the case of the former, check the cooker is adequately insulated and the lid is properly sealed, and in terms of the latter check the orientation of your cooker to the sun. The angle of the sun’s rays to the cooker must be maximized to achieve optimum performance from the cooker.

  To cook effectively in most solar ovens you need to allow the sunshine in to heat the environment and at the same time you need to trap the heat inside as best possible. To do this efficiently ensure you have tight-fitting lids to make your solar cooking utensils as air-tight as possible, and once

you start cooking avoid opening the pot or pan and ensure you minimize or preferably avoid completely opening the solar cooker cavity.

  Ensure the plastic or glass cover remains tightly closed. Every time the heat seal is compromised the cooking becomes less efficient.

  Prepare the food as per the relevant recipe, and then add the food to the pots/ pans. Avoid the temptation of adding excessive water to the food, strictly add the amount of water as stipulated in the recipe (solar cooking recipes use a lot less water compared to conventional recipes as no water is lost through evaporation during cooking). Carefully position the pots/ pans in the cooker as close to the back of the cooker as possible, but avoid actually making contact with the side of the cooker. When initially placing the utensils in the cooker, use the oven gloves as a safety precaution. Direct contact with your skin against the side of the pre-heated cooker can cause a painful burn.

  Set up your cooker with the food allowing adequate cooking time. The rule of thumb is to put out the food as early as possible. Even with excessive, direct sunlight the food will not burn due to the low thermal flux dynamic and in most protein dishes the slow cooking principle is personified with the longer the cooking time the more tender and delicious the meat as the gradual cooking process tends to soften the connective tissue without toughening the muscle, which is particularly appropriate for curries, stews and casseroles, although essentially virtually any form of food can be cooked in this manner.

  This slow cooking dynamic also serves to preserve the natural vitamins and nutrients in the food. In addition the solar cooking process does not result in the pot boiling over, even when left unattended.

  With certain carbohydrates, extensive cooking can eventually lead to a breakdown in food texture and consistency. Similarly fish can eventually dry out if cooked excessively in a solar cooker. Full sunshine is best. The more overcast the day the longer the cooking time will be required. At least partial sunshine is necessary.

  The cooking experience is optimized if you adjust the position of the cooker approximately every 1-2 hours to follow the arc of the sun thereby maximizing exposure to the sun. If you anticipate being away all day, face the cooker due south for the day in the northern hemisphere and north for the day for the southern hemisphere.

  Certain types of food may cook better with a more frequent adjustment of the position of the cooker but you need to experiment as you use your cooker. Generally your best cooking times are in the middle of the day, in the 10h00 to 14h00 zone.

  The total time required to cook a meal varies, depending on circumstances, but with adequate sunshine this should be two to three times that of conventional cooking. Less water and a lot less stirring is another important dynamic. Times differ widely for the various different types of food.

  Due to the remarkable heat retention of most solar cookers you can cook a meal in full sunshine during the day and leave the meal in the pots in the cooker until you are ready to eat in the evening, with minimal loss of heat, although the heat retention does vary according to circumstances, what

design of solar cooker you are using and the heat retention characteristics of the solar cookware.

  Most solar chefs tend to favor thinner, enamel solar cooking pots as the food heats up faster. The thicker pots tend to heat up more slowly but conversely are better at retaining the heat for longer periods of time.

Solar Water Pastuerization

  Wikipedia refers to solar water pasteurization as solar water disinfection (also known as SODIS) and describes it as a method of disinfecting water using only sunlight and plastic PET (polyethylene) bottles. SODIS is a free and effective method for decentralized water usually applied at the household level and is recommended by the World Health Organization as a viable method for household water treatment and safe storage.

  Similarly Wikipedia defines pasteurization as a process which slows microbial growth in The process was named after its creator, French chemist and microbiologist Louis The first pasteurization test was completed by Louis Pasteur and Claude Bernard on April 20, 1864. The process was originally conceived as a way of preventing wine and beer from souring.

  Pasteurization is not intended to destroy all pathogenic micro-organisms in the food or liquid. Instead, pasteurization aims to reduce the number of viable pathogens so they are unlikely to cause disease (assuming pasteurization product is stored as indicated and consumed before its expiration date). Commercial-scale sterilization of food is not common because it adversely affects the taste and quality of the product. Certain food products are processed to achieve the state of commercial sterility.

  Answers.com defines pasteurization as the act or process of heating a beverage or other food, such as milk or beer, to a specific temperature for a specific period of time in order to kill microorganisms that could cause disease, spoilage, or undesired fermentation.

 

Whilst clean drinking water is taken for granted in most first world countries, it remains a continuous challenge in various developing countries where contaminated water, especially water contaminated with faecal-borne bacteria, viruses, and protozoans (cysts of protozoa) continues to negatively affect millions of people, in particular the young and the elderly (it is estimated that only 50% of people in Africa have access to safe drinking water).

  Global estimates are that one billion people do not have access to safe water and that diarrhea kills anywhere between 2 to 5 million children and causes in excess of a billion episodes of illness each year. Diarrhea is caused by pathogenic microbes (bacteria and rotaviruses) being ingested, frequently from contaminated water.

  UNICEF (United Nations Children’s Fund) maintains that diarrhea is the most common childhood disease in developing countries, resulting in dehydration and child malnutrition, which apart from potentially leading to death can also result in permanently impaired mental and physical development in children.

  Research has clearly demonstrated that it is not necessary to boil water, nor is it necessary to distill water, to make it safe to drink. Heating water to 149°F (65°C) and holding it briefly at that temperature (a minimum of 6 minutes) will kill the majority of microbes, viruses, and parasites (including the hepatitis A virus). This is the process of pasteurization and in its simplistic form is what is required to effectively provide safe drinking water.

 

In reality water pasteurization is frequently not practiced in developing countries, either due to a lack of education and understanding or due to the scarcity of heating fuel or a combination of the two. Solar water pasteurization offers a simple and relatively inexpensive solution to this through one of two means, either by the application of the basic principles of solar heating without using a solar cooker, SODIS, alternatively using one of various solar cooker approaches available.

  SODIS (Solar Water Disinfection) Solar Water Pasteurization

  SODIS (short for Solar Water Disinfection), was an approach initially researched and developed by Professor Aftim Acra at the American University of Beirut in the early 1980s and is currently an initiative of Eawag, the Swiss Federal Institute of Aquatic Sciences and Technology. Eawag, for more than 10 years, have been committed to providing people in developing countries with access to clean, drinking water therein reducing infant mortality, and as a consequence make a direct contribution to the millennium development goals of the

  Fundamentally SODIS is a technique that disinfects water using sunlight and plastic polyethylene bottles, glass bottles or clear plastic bags. The principle is the contaminated water is filled into a transparent PET bottle, glass bottle or clear plastic bag and then exposed to direct sunlight for a minimum of 6 hours, preferably during the hottest part of the day. Microbiological research by Eawag (Franziska Bosshard ) has demonstrated that from a mechanistic perspective the ultra violet radiation of the sun (wavelength 320-400 nm) reacts with dissolved oxygen in the water to cause the formation of reactive oxygen species(oxygen free radicals and hydrogen which attack and destroy the membrane proteins (which provide key functionality with respect to energy generation) of the pathogenic bacteria. This then causes a domino effect and leads on to other widespread protein damage and the aggregation of proteins, causing permanent structural damage to the cell, ultimately resulting in the complete inactivation of the vegetative cell.

 

When the water temperature exceeds 86°F (30°C), a threshold solar radiation intensity of at least 500 is required for a minimum 5-6 hours for the SODIS effect to be fully realized. Once the water temperature exceeds 113°F (45°C), disinfection efficiency is further enhanced and when the water temperature exceeds 122°F (50°C), the disinfection process is accelerated three-fold.

  SODIS has proven to be a fairly simple but extremely effective technique in pasteurizing water in the absence of heating water using some form of fuel or alternatively a solar cooker. It is also highly cost-effective in comparison to most of the conventional methods of water treatment, including gaseous chlorination, microfiltration, tablets (chlorine, bromine and iodine tablets), flocculation, acid treatment (low pH manipulation) etc. The application of a SODIS approach has particular value in less developed areas that have significant incidence or risk of water-borne diseases, for example refugee camps, war zones and disaster-struck environments. It is also a technique that does not require a high level of technical skill to apply.

  The detailed, sequential procedure of SODIS is as follows:

  Select clean, transparent PET bottles, glass bottles or clear plastic bags of 2 litre volume or less (excessive depth of water must be avoided. At a water depth of 4 inches (10 cm) and moderate turbidity of 26 NTU, ultraviolet radiation is reduced by 50%). It is critical that the construction of the container allows full and adequate penetration of the sun’s ultraviolet light.

  Certain types of container construction will have negative barrier properties. Materials that should be avoided include polypropylene, glass

fiber, polycarbonate, aluminum foil, PVC and nylon.

  Select a sufficient quantity to allow for adequate water reserves. Ensure the containers have few or preferably no scratches and all labels have been removed. Avoid old, perished containers. Wash the empty containers to remove any visible signs of dirt, insects or general contamination.

  If possible filter the contaminated water before filling the containers. The smaller the filter pore size the better, but practically a clean, fabric cloth should suffice (filtration is strongly recommended for water that is visually cloudy with a turbidity higher than 30 NTU (Nephelometric Turbidity Units)).

  The contaminated water is now filled into the containers. Fill each container about 75% full, seal the container and briefly shake the container vigorously. Open the container, fill to capacity and reseal the container. This vigorous shaking enhances oxygen saturation which amplifies the disinfection action (the water must contain in excess of 3 mg oxygen per liter and the shaking action will adequately achieve this).

 

  Photo courtesy of Wikimedia Commonsat http://commons.wikimedia.org/wiki/File:Indonesia-sodis-gross.jpg Author: SODIS Eawag

  The containers must then be positioned on an angled, sun-facing roof, preferably a corrugated metal roof that will absorb and retain the heat from the sun as opposed to a roof constructed from a material that is less absorbent, for example a straw or thatched roof. The containers will heat up faster and achieve a higher internal temperature of the water by selecting a roof that is more absorbent.

  Ensure the containers are directly exposed to the sunlight and there is no obstruction or obstacle that will cause shade or a shadow during the day. Ensure the containers are placed in a single layer, in other words avoid

stacking containers on top of other containers as this could eventually dilute the effect of the sun.

  Ensure the containers with the contaminated water are exposed to direct sunlight for at least 6 hours. Under cloudy conditions (but no rain) allow at least 2 full days, although the rule of thumb is the longer the better, but definitely not less than 6 hours under cloudless conditions. Failure to sufficiently heat the water could result in the overall pathogenic bacterial load remaining too high, which could still lead to illness should the water be consumed.

  If at all practically possible after heating, the containers should now be refrigerated and stored under refrigeration until used. The refrigeration process directly subsequent to the completion of heating will further enhance the effect of disinfection by inducing cold shock to any surviving bacterial cells. Rapid cooling to a temperature at or just above 0°C, leads to the alteration of lipids in the bacterial cell membrane, an effect that damages the permeability of the cell and in certain instances this cold shock also induces the release of repair enzyme inhibitors by the cell, causing the cell to self-destruct. In both cases the vegetative cell is permanently deactivated.

  It is a theoretical possibility that bacteria in the disinfected water can reproduce once removed from sunlight and placed in a dark environment, albeit at a substantially reduced rate.

  Good practice is to continue to store the disinfected water in the original containers. Any further downstream decanting into other storage containers increases the effect of double handling and increases the risk of cross-contamination.

  Solar Water Pasteurization and purification using a Solar Cooker or Equivalent Device

  To pasteurize contaminated water using a solar cooker is in essence as easy as using the solar cooking principles but using water instead of food. The process becomes judicious and less subjective if you can include a specific, objective measurement to ascertain that the correct temperature has been achieved.

  The principle of pasteurization remains a function of both temperature and time, with the requirement being heating to 149°F (65°C) for 6 minutes or longer (but a minimum of 6 minutes).

  To this end the WAPI (Water Pasteurization Indicator) concept was first developed in 1988 by Dr. Fred Barrett (US Department of Agriculture) and in 1992, Dale Andreatta, a graduate engineering student at the University of California, Berkeley, improved the design and developed the current WAPI.

  The WAPI is a polycarbonate tube about 3 inches (7.5 cm) in length, sealed at both ends, and partially filled with a soybean fat which melts at 156°F (69°C). It also has a nylon thread and stainless steel washer attached that allows the tube to be inverted once the fat has melted and then subsequently cooled and solidified. The tube fundamentally is buoyant but is weighed down by the washer.

 

The WAPI is positioned inside the water container and secured at the bottom of the container, usually by means of a washer. The bottom of the water container is important as this is the coolest part of the water container in terms of solar heating. The top of the container will heat first in terms of proximity to the sunshine.

  Once the temperature has reached 149°F (65°C) at the bottom of the water container this indicates that the temperature is at least the same elsewhere if not higher.

 

  Generally the water temperature at the top of the container is about 2-5°C hotter than the water temperature at the bottom.The solar cooker is then employed and water is then heated using sunshine.

  When a temperature of 149°F (65°C) is attained after a couple of hours and that temperature has been maintained for 6 minutes the fat melts and migrates to the bottom of the WAPI, indicative of pasteurization having been successfully completed. Should the fat not melt this indicates the correct temperature-time regime of 149°F (65°C) for 6 minutes has not been achieved.

  The current design allows the WAPI to be reused as well. Once the fat cools down and solidifies at the bottom of the polycarbonate tube the tube is inverted and nylon thread is then moved to the opposite end and the washer slides to the bottom, which effectively positions the fat at the top of the tube, allowing the process to be repeated.

  The nylon thread also allows the tube to be removed from the water container without the risk of cross-contamination. The WAPI kits are inexpensive and cost about $3 each. These kits can obviously also be used in conventional (non-solar) heating of water, although the original intent is to measure solar heated water pasteurization.

  Once the water has been successfully pasteurized it stands to reason that it is then critical that the correct antiseptic procedure is followed to sustain the integrity of the water, in particular that the water is carefully decanted into clean and sterile storage containers and that the same containers are correctly stored. The correct and repeated education of rural communities is paramount in terms of a successful and sustained program of solar water pasteurization.

 

With regard to the basic methods of solar water pasteurization using a solar cooker or equivalent device the following approaches are commonly employed:

  Solar Cooker

  This approach is to simply put blackened water containers containing water into a solar cooker and to heat the water in the same way that food would be heated, utilizing all the same principles and ensuring continuous, full exposure to the direct sunlight (as described in how to use a solar box page 6) and ensuring a WAPI kit is also employed.

  Depending on the physical size of the solar cooker up to 15 litres a day of water can be pasteurized. Solar box cookers and solar panel cookers are regularly employed with solar water pasteurization, although these cookers tend to be utilized more by individuals or families.

  Flow-Through pasteurization devices

  A flow-through solar pasteurization device works on economies of scale to produce pasteurized water on large scales compared to individual solar cookers. The principle is based on the industrialized heat exchanger principle. The design encompasses a length of black tubing coiled within a standard solar box cooker. One end of this tubing is connected to a thermostatic valve and the other to a storage tank for the untreated water supply.

  This storage tank contains a sand filter that does the initial filtering (similar to a swimming pool filter concept). The tubing is designed to hold less than 2 liters of water at any one time which leads to accelerated heating of the water.

  The thermostatic valve opens at 182°F (83.5°C) which is above the indicative pasteurization temperature but is designed to build in a margin of safety. The pasteurized water drains out of the tubing and into another storage vessel for post-pasteurized water.

  As the pasteurized water drains from the solar box cooker, contaminated water from the storage tank automatically refills the tubing. Once this cool water reaches the valve the valve shuts and the pasteurization process is repeated.The energy saving is personified when the hot pasteurized water exits the cooker into a simple counter-current heat exchanger where much of its heat is transferred to the cold water that is entering the cooker.

 

When compared to the simple solar cookers that pasteurize water on a batch-type basis this flow-through (heat exchanger device) is more expensive, but it does offer a more continuous, commercial approach to solar water pasteurization.

  Pasteurized water is made available in larger volumes (up to ten times the volumes compared to a solar cooker) and on a more continuous basis and the entire process is more automated in nature. The final product is also cooled down which reduces the risk of accidental burning.

  Solar Puddle

  There are numerous variations of the solar puddle but conceptually the design is literally a puddle in a greenhouse, in other words a shallow body of water kept under two clear plastic sheets. The heat from the sun is effectively trapped under the plastic layers which causes the water to heat up and eventually to reach the correct pasteurization temperature-time regime of 149°F (65°C) for 6 minutes.

  The benefits of the solar puddle are it can pasteurize a relatively large volume of water, it does not require an enhanced technical skill to build and it is relatively inexpensive to manufacture. Solar puddles are also available commercially.

  To construct a solar puddle the following sequence needs to be adhered to:

  Dig out a shallow basin with a horizontal base about 2.5-4 inches deep (10-12cm). Design your overall area to the volume of water you intend to pasteurize on a daily basis. A 1m x 1m area would be suitable for an average family requirement.

  Do not make the basin too deep and position the basin at some high point on the property, keeping in mind that you will need to gravity feed your pasteurized water out of the basin into storage containers once pasteurization is complete.

 

Fill the base of the basin with about 2 inches (5cm) of insulating material (for example straw, newspaper, leaves, bark etc). Flatten and level the layer of insulation and in the one corner allow a slight concave depression, just under 1 inch (about 2 cm) lower at its lowest point compared to the rest of the basin. Allow enough space to fit a WAPI kit into the depression with the end of the drainage pipe.

  Embed a layer of clear plastic and then a layer of black plastic over the insulation with the edges of the plastic extending up and out of the pit. Two layers are used to minimize the risk of water leaking out. An inexpensive high density polyethylene of at least an 80 micron thickness can be used.

  Add sufficient water to cater for your pasteurization requirement but not deeper than 2.5-3inches (7cm). Add a WAPI kit to the concave depression, as this is the area that will heat up the slowest.

  Measure a sufficient length of piping (for example piping from a common garden hose pipe) to allow complete drainage of your basin into storage containers once pasteurization is complete.

  The discharge end of the pipe must be lower than the lowest point of the solar puddle to allow for pasteurized water to be properly siphoned out.

  Ensure this drainage pipe is clean and sterile and fill it with pasteurized water. Seal the pipe at the one end with a clip or sterile plug so that no leakage occurs and close the pipe at the other end with your thumb (remember to carefully wash your hands first).

 

Secure that end of the pipe at the lowest part of the basin (in the concave depression alongside the WAPI kit) using an object to anchor the end of the pipe (for example a sterilized rock or sterilized weight).

  Cover the basin with another sheet of clear plastic (similarly high density polyethylene of a minimum thickness of 80 micron will suffice) and position various spacers that will ensure a sustainable insulating gap of about 2 inches (5cm) between this third layer of plastic and now on top of that place a forth layer of identical plastic.

  Ensure the edges of the third and fourth layer of plastic also extend beyond the edges of the basin. These top two layers of plastic trap a layer of about 2 inches (5 cm) of air.

  The light entering the solar puddle from the top effectively heats up this trapped air which in turn heats up the water (acting as a catalyst to heating the water to pasteurization temperature).

  Secure the 4 layers of plastic sheets by placing weights or rocks on the edges of the plastic sheeting. Prior to positioning the plastic ensure all four layers are clean and sterile.

 

  Monitor the solar puddle during the course of the day and once the WAPI indicates pasteurization has been successfully completed then position your sterile storage containers close to the discharge end of the pipe below the lowest point of the solar puddle, remove the clip/ plug from the pipe and monitor the flow of pasteurized water into the container.

  Just before completely emptying the basin ensure that the discharge pipe is completely filled up with pasteurized water and sealed using the clip on the discharge side.

  The solar puddle can be repeatedly used day in and day out. Replenish water in the basin by either lifting the edges of the top two layers of plastic and adding water using a bucket or using a second pipe to fill the

basin, keeping in mind that the discharge pipe has to be used exclusively for discharge purposes as it needs to remain clean and relatively sterile.

  Solar Distillation

 

  Solar distillation is a distillation technique employing a solar still. There are three basic types of solar stills, box, and pit and more recently a plastic cone that operates in similar fashion to the box.

  The principle of solar distillation is that contaminated water is contained outside of a collector and is then exposed to the heat and humidity of sunlight. Evaporation is induced by sunlight shining through clear plastic. The cool inside surface of the plastic then subsequently induces condensation of pure, unadulterated water vapour which drips down to a low point where it accumulated and is reclaimed.

  Commercial solar stills are available although commercial use is not widespread. The domestic designs usually account for a daily volume of water of between 1-3 liters. On the upside is that apart from the initial purchase outlay the devices are easy to use, require minimal maintenance and operate automatically with very little practical intervention necessary. Solarsolutions market a small plastic cone called the This design is a floating water purifier that is lightweight and very portable. The condensing cone is made of durable and UV protected polyurethane film.

  The device is designed to remove a very wide variety of contaminates including microbiological pathogens, heavy metals, salts, and other chemicals. The plastic cone floats on any source of water and can also function to desalinate sea water. The physical construction is characterized by a condensing cone assembly and an inflatable-insulating floor.

  The cone assembly consists of a transparent cone welded to an integrated support tube and clean water collection pocket. The inflatable floor has an evaporative wick attached to its top surface. The floor sits underneath the cone and is composed of an inflatable insulator attached to an evaporative surface which is kept warm by insulating it from the source water.

  The principle is that sunlight shines through the transparent cone warming an evaporative wick (water-soaked pad). The wick is fabricated from fine fibres and droplets of water stick to these individual fibers, which allows for a large surface area of evaporation. The air inside the cone eventually becomes saturated with water vapour.

 

The sunlight increases the internal heat inducing the hot air to rises and condense against the cooler surface of the cone. The pure condensation then gravity feeds back down the cone into a collection pocket around the base of the cone. Once sufficient pure water has been collected in this fashion it can be drained through an outlet valve into a storage container.

  In this process the pure water is separated from the contaminants which remain behind in the wick. The wick can be removed and cleaned on a regular basis. The cone also functions to some extent in the evening when the temperature difference between sun-warmed water and cool night air is exploited to produce up to a liter or more, over and above normal daytime production. During a normal day time operation the cone should produce between 1-3 litres of pure water depending on local circumstances.

  Water Pyramid technology applies the same principles but on a commercial-scale and is generally referred to as large-scale solar distillation designed for community-sized projects as opposed to family sized projects. The design is also to purify contaminated water (including the removal of arsenic and fluoride) and can also be used to desalinate salt water.

  Martijn Nitzsche, a Dutch engineer, founded Aqua-Aero Water Systems and in the early 2000s, the company invented the WaterPyramid technology. This technology was later rolled out with a partnership with MWH (an engineering firm involved in the wet infrastructural sector globally).

  The Water Pyramid, similar to the AquaCone, is a cone shape structure that is 26 feet (8m) high and 98 feet (30m) in diameter and covers 625m

of surface space. It is manufactured from plastic sheeting and is inflated by a solar-powered fan. On days of full and direct sunshine the Pyramid can achieve internal temperatures of 167°F (75°C).

  A thin layer of water is pumped inside the cone and the high internal temperatures induce evaporation, ensuring any dirt, saline or contaminants remain on the ground. Condensation on the sides of the Pyramid then occurs subsequent to evaporation and pure, distilled water gravity feeds down the sides of the pyramid wall and is collected by gutters that feed into a collection tank.

  One Pyramid can distil 265 gallons (1000 litres) of water every 24 hours under optimum conditions. The relationship between the volumes of pure water produced each day versus the number of Pyramids is a simple straight line relationship. To double the daily production the community simply needs to acquire another Pyramid (at a cost naturally).

  A further design benefit of the Pyramid is that when it rains due to the large size of the structure, the rainwater runs down the outside of the Pyramid and is harvested by external gutters and stored for the community use.

  In 2006, the water pyramid project received an innovation award (Development Market Place Award) of the World Bank for small-scale water innovations.

  The ultimate survivalist form of solar distillation is to construct a Condensation Essentially the approach is to find a tract of land that you deem suitable to for a condensation pit.

  Preferably in the bed of a dried up river, alternatively low-lying ground. The area must receive full sun during the entire day. Dig the pit at least 1m deep and ensure you observe signs of moisture in the layered soil as you dig down. When you construct these pits experiment with varying depths to test which depth gives you the best result.

  Keep in mind your primary goal is to harvest pure water, so depending on your set of circumstances and the degree of permanence you attach to the installation, you might want to add anything into the pit that is water absorbent and will supplement your source of water from the soil, for example green non-toxic succulent plants or vegetation. You could even add in a source of water that still needs to be purified.

  Place a water receptacle (for example use a small, plastic bucket and avoid using any container that could rust) in the bottom, centre of the pit. Position a sterile siphoning tube in the bottom of the container (if possible with some form of attachment that secures the pipe at the bottom end of the container).

  Run the tube out the pit and downwards, preferably so that the bottom, discharge side of the tube is positioned at a point that is physically below the actual level of the water receptacle. This is not always practical, but if possible engineer the situation as such.

  Now stretch a piece of plastic over the top of the pit to ensure the pit is air-tight. A recommendation is to use a translucent, high density polyethylene of at least 80 micron (or a higher gauge).

 

The plastic must be clear to glean full advantage of the sunlight coming in and subsequently acting as a catalyst for the trapped air to heat up. If you have decided to make the pit permanent or semi-permanent you need to ensure that the siphon tube running out does not compromise the integrity of the pit being air-tight. To this end some form of non-return valve or similar sealing device would be appropriate.

  Seal the top layer of plastic completely by using sand, rocks or a combination of both. Add a small to medium size rock or weight on top in the middle of the plastic to slant the plastic downwards towards the center, forming a kind of inverted funnel.

  Once the sun rises the sunshine and heat in the pit will induce evaporation. The water vapour is driven out of the soil and vegetation. The water vapour rises and comes into contact with the plastic. The surface of the plastic is cooler than the water vapour and as a consequence condensation occurs, whereby the water vapour undergoes a phase change and forms back into water.

  Britannica Concise Encyclopedia defines condensation as: Condensation usually occurs on a surface that is cooler than the adjacent gas. A substance condenses when the pressure exerted by its vapour exceeds the vapour pressure of its liquid or solid phase at the temperature of the surface where the condensation is to occur. The process causes the release of thermal energy.

  The condensed water than gravity feeds down the outside of the funnel inside the pit, and gradually but progressively drips into the water receptacle, slowly filling with water. Once sufficient water has collected a

suction can then be applied to the tube, siphoning the water out of the receptacle.

 

Different Types of Solar Cookers

  Box solar cookers

  The box solar cooker is probably the most common type and most widely used of the solar cookers. It is also invariably a fairly low-cost option. The majority of the box cookers are literally a box concept personified, although there are also designs that are rectangular, circular, oval, coneshaped or a combination of two or more shapes.

  The exterior design varies depending on the sophistication of the construction, but most commercial box cookers commonly consist of a tough, blow-moulded, black, exterior, manufactured primarily out of polyethylene. The internal design is simplistically an inner box compartment that is either square-shaped or has a slightly concave look to it, with the sides angled out to maximize the solar collecting area and reduce the internal volume to be heated.

  The internal walls of some of the box solar cookers are sloped, thereby concentrating and conducting the energy of the sun. This internal area is insulated and has some form of reflecting surface dynamic, usually the walls, which are commonly lined with a shiny aluminum foil to reflect and concentrate sunlight towards the center of the box.

  In certain other box designs there is a separate, external lid that is paneled with some form of reflective material and acts as the main source of reflection. The bottom of the box cooker is normally painted black (black is the most effective colour in absorbing and retaining heat) and the inner box is sealed or closed with a thick plastic or even glass.

  The inside insulation for the box has to be able to withstand temperatures up to 300°F (150°C) or there about without melting, perishing or liberating any form of secondary gases or odours. Various materials including newspapers, wool, rags, dry grass, sheets of cardboard, etc can be used to insulate the walls of the solar cooker, but since most of the heat escapes through the top glass or plastic, it is not necessary that the side walls are over-engineered with respect to insulation.

  The top must be transparent and able to effectively trap as much heat as possible, which necessitates a tight, integral seal. Normally the top is manufactured from plastic (preferred), glass (which is effective and durable but can pose a safety risk in terms of handling and storage) or even an oven cooking bag, which is light-weight, inexpensive, easier to work with, but less robust.

  Most box solar cooker typically reaches a temperature of 300°F (150°C). This is not as hot as a standard oven, but still hot enough to cook food over a somewhat longer period of time. Food containing a lot of moisture cannot get much hotter than 212°F (100°C) in any case, so it is not always necessary to cook at the high temperatures indicated in standard cookbooks.

  Because the food does not reach too high a temperature, it can be safely left in the solar cooker all day without burning. It is best to start cooking before midmorning if at all practical. Depending on the latitude and weather, food can also be cooked either early or later in the day.

 

The solar cooker can be used to warm food and drinks and can also be used to pasteurize water or milk. Fundamentally a solar box cooker can be described as a “sun-powered oven” that works surprisingly well.

  Solar box cookers strangely enough can also conversely be used as a type of solar refrigerator in the evenings. On condition that the infrared transfer in not inhibited in any way by not using a glass or plastic lid, in other words leaving the cooker completely open, and the cooker is positioned where it is fully exposed to the sky on a clear, windless night, internal cooling actually occurs, relative to ambient cooling.

  If you place an object inside the cooker under these conditions the object actually cools to a temperature lower than that of the ambient air conditions, and in certain instances a small deposit of water will actually ice up in a cooker, relative to water outside the cooker exposed to the same conditions that lowers in temperature but does not ice up.

  The theory is an object in a cooker emits infrared energy and receives a lot less infrared energy than an object outside of the cooker, and hence cools down to a greater degree, and can be measured as much as 3-4 °C cooler than the external object.

  Box solar cookers can be made from a variety of locally available materials or be manufactured on a commercial-scale. Box cookers range from simple, small, homemade cardboard devices (even as simple as a shoebox or disused pizza box), suitable for cooking a single meal when the sun is shining, to larger wood, glass or polyethylene boxes that can accommodate a number of cooking pots and pans simultaneously.

 

Most box solar cookers are portable, but these can also become permanent features built into a house or outside patio, similar to a barbecue or pizza oven.

  These surprisingly simple, easy-to-use and enjoyable devices are ubiquitous all over the world and have become a firm favourite for school projects, campers and numerous “weekend chefs”. On a more commercial perspective these box solar cookers have also been widely used in global rural settings that have traditionally used fossil fuel sources to cook food.

  One of the most well-known solar box cookers in the second decade of the century is undoubtedly the Koyota Box Cooker. Designed and manufactured by Kenya-based entrepreneur Jon Bøhmer, this cooker is touted as a solar-powered cardboard cooker which aims to transform the lives of hundreds of millions of villagers in developing countries.

  The Forum for the Future describes the Kyoto Box solar cooker as the 2009 global winner of the $75,000 Financial Times Climate Change Challenge organized by the Forum for the Future, for innovation to tackle climate change.

  The Kyoto Box solar cooker functions as a classic solar box cooker allowing the inbound sunshine to enter the inner box where the solar radiation is captured and used as a heating medium. The design is that of two different size boxes, one bigger than the other. The design is covered with an acrylic lid.

  Black paint on the inner box and silver foil on the outer help concentrate the heat, while a layer of straw or newspaper between the two provides

insulation. The cooker is a typical solar box cooker but with a difference. The costs are deliberately kept as low as possible to make the cooker more affordable to a global audience. This solar cooker is constructed from recycled polypropylene which is completely non-toxic and engenders a substantial longevity to the design.

  Bøhmer also intends to introduce thermographic plastic indicators which will display three temperature indicators, each with their own unique color which will be easily visually identified through the glass cover.

  The indicative temperatures will be once pasteurization temperatures have been successfully achieved at 154°F (68°C), once successful cooking temperatures have been achieved at 185°F (85°C) and one indicating that the food is still hot enough to avoid bacterial contamination 113°F (45°C). Future functionality will include cooling and desalination features.

  The Forum for the Future describes Bøhmer as the founder and chief executive of Kyoto Energy, a Nairobi-based design and engineering company working on novel energy solutions for the developing world. He plans to use the prize money to conduct mass trials in ten countries, including India, Indonesia, South Africa, Kenya, Uganda, Tanzania, Mozambique and Liberia.

  He has developed a more robust, longer-lasting solar oven in corrugated plastic, which can be mass-produced in existing factories as cheaply as the cardboard solar oven prototype, and he intends to produce 10,000 to use in the trials. The trials will generate data to back an application for carbon credits, the crucial element which will make the project scalable, he explains. He expects each solar cooker stove to make a yearly profit of 2030 euros, which will more than cover the manufacturing cost.

  Arguably the most popular and widespread sold solar oven in the world today is the Global Sun Oven solar cooker manufactured by Sun Oven International. It is categorized as a box solar cooker, is black on the inside and is very well insulated. It is designed with a tough plastic exterior and four top, external mirror reflectors that fold up easily over the box and fit snugly and securely into a folded position.

  This solar oven is designed to achieve internal temperatures in excess of 350 °F (177°C), which implies that this cooker is extremely versatile and can cook virtually any food type available, including the notoriously fickle breads and cakes which can very easily collapse during cooking if either the internal heat seal is disturbed or the internal temperature does not get high enough).

  The design is also commercially constructed out of very good quality raw materials which engenders exceptional longevity if properly maintained, cleaned and stored. This Global Sun Oven can literally last a lifetime if properly looked after. In addition it is relatively lightweight at 21 lbs (9.5kg), robust and cooks faster (due to the higher internal temperatures) than the vast majority of solar ovens.

  The sun oven is also highly portable by nature and folds up into a compact suitcase-type package. It conversely can be opened up in seconds with the peripheral all round reflectors easily snapping into place. Food can be boiled, steamed, fried and baked. The design also comes with a manual level adjustment to maximize the exposure to the sun.and a built-in thermometer. The exterior of the solar oven does not get hot and as such is very safe (although appropriate gloves need to be used internally).

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:GSO.JPG Author: Atlas de la Cuisine Solaire

  Panel solar cookers

  A French scientist Roger Bernard designed the first prototype panel solar cooker in addition to the Nelpa panel cooker. Panel solar cookers are very inexpensive solar cookers that use flat, shiny, reflective panels to focus and concentrate sunlight onto a cooking pot that is enclosed in a clear plastic bag.

  In essence it is similar to the solar box cooker concept except in the majority of panel cooker designs there is no internal box. There are literally a number of reflective panels (usually four) and the cooking vessel in a plastic bag (the plastic bag functions to retain the heat). Generally the reflective panels are cardboard, metal or wood and are lined with aluminum foil (in certain instances the reflector is polished aluminum).

  The advantage of the panel cooker is the simplistic and inexpensive design, relatively low-cost and the fact that certain designs are foldable makes it compact, portable and easy to store. It is also easy to clean.

  The disadvantage is these designs have a propensity to retain less heat, to reach temperatures of between 210-300°F (100 and 150°C) which is not as high as what other cookers achieve, to lose heat quicker and to become unstable in high wind conditions (panel cookers are more susceptible to sudden changes in ambient conditions compared to box and parabolic cookers).

 

It is also sometimes difficult to source heat-resistant oven bags and these bags through frequent handling have to be replaced on a semi-regular basis which has a cost implication.

  Although these cookers do not achieve the equivalent temperatures achieved by the box and parabolic cookers, the panel oven will still reach high enough temperatures to cook most foods and to pasteurize water, albeit with a longer application resident time.

  Some panel designs uses parabolic reflectors positioned above a box-type oven. Panel solar ovens are often described as being unique in that they incorporate elements of both a parabolic and box oven.

  Usually a panel solar cooker is folded into the shape of a basin. Similarly to the box cooker, the food is prepared and then placed in a dark pot with a snug-fitting lid. The pot is the encapsulated in a transparent, plastic bag (any clear plastic bag will work, although a more robust roasting bag will last longer and can be reused on numerous occasions).

  The bag must then be tightly sealed to disallow any movement of air. Position the pot in the bag in the center of the cooker.

  The panel solar cooker is then exposed to direct sunshine, preferably as early as possible (not later than midmorning) and left for a couple of hours until the food is cooked. Certain designs need to be occasionally adjusted to follow the arc of the sun and in certain instances cooking can be accelerated by elevating the pot slightly, using an appropriate structure or even sticks or a wire frame, allowing hot air to circulate beneath the pot.

 

Two common panel cooker models are the CooKit and the Hot Pot, both of which are widely used throughout the world. The CooKit was designed and developed by Solar Cookers International in 1994.

  It is a low-to-moderate temperature solar cooker which is approximately 1m x 3m (3x10 feet) and is constructed from cardboard and aluminum foil. Certain trials have been conducted constructing CooKits from plastic to make the design more durable and robust. Mixed success has been reported with one of the disadvantages being a difficulty in folding the cooker.

  The Hot Pot was developed by Solar Household Energy, Inc and the design was completed in 2004. This design differs slightly from the CooKit in that it consists of an enamelled, black steel pot positioned inside a covered, transparent, tempered glass bowl, not dissimilar to a conventional slow cooker.

  The glass bowl negates the need for a plastic bag. There is a small air space between the pot and the bowl of about 1.3 cm (half an inch) which creates a hot air envelope. This design allows for heat to be retained inside the glass bowl which sustains an elevated, uniform cooking temperature.

  The glass bowl allows the entire cooking process to be visible which reduces the need to open the pot to check the cooking progress. The assembly is also heavier than the CooKit which allows more stability in windy conditions.

  There are two reflectors which fold easily for storage and which function to focus the sunlight onto the pot.

  The sealed characteristic of the cooking pot allows for accelerated internal heating with temperatures of 350 to 400°F (175 to 200°C) regularly achieved. The cooker is positioned centrally at the bottom of a large series of reflectors which are lined with anodized aluminum. These reflectors function to focus the sunlight onto the pot and are easily foldable taking up minimal space, making the HotPot extremely portable by nature.

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Cuiseur_solaire.JPG Author: Cédric Filhol

  Solar kettles

  One of the less conventional solar oven devices is a solar kettle. These kettles fall within the category of a solar cooker and although more renowned for heating liquids, in certain instances can be used to cook food as well. Wikipedia describes these devices as “solar thermal devices that can heat water to boiling point through the reliance on solar energy alone”.

  There are a handful of these solar kettle devices available although fundamentally the more well-known designs are as follows:

  The solar kettle-thermos flask is a solar thermal design, developed by Alex Kee in 2006, that uses an evacuated solar glass tube (solar vacuum glass tube) constructed from borosilicate glass to capture and store energy from the sun. The tube consists of an inner glass layer characterized by a dark exterior that heats up in sunlight, whereas the outer glass layer is transparent allowing sunshine to penetrate.

  This sunshine transports the solar infra-red energy and penetrates through this outer layer and subsequently through the vacuum layer onto the inner layer where it is absorbed.

  The air is evacuated between these two layers with a consequent insulating vacuum. The vacuum effect is disproportionately powerful due to minimal air or the absence of air.

 

Without air molecules present (or with very little air molecules present), heat cannot move around and remains trapped which ensures the environment gets hotter and retains the heat for longer, in much the same way that a vacuum flask keeps liquids hotter for longer periods of time.

  The stagnating temperature of solar vacuum glass tubes is a high 425 °F (220 °C), a prevailing dynamic that enables the solar kettle to store energy and boil water or other liquids. In addition this energy storage technology, using vacuum insulating properties, allows the kettle to run after sunset as long as the kettle has been charged up during the daylight hours.

  This kettle has a simple assembly of a tube stand angled at approximately 45 degrees, through which the solar kettle is inserted and then adjusted towards the sun.

  Thereafter the tube is filled with approximately 2 liters of water and sealed tightly with a cork. Usually in full sunlight pasteurization temperatures can be reached within 2 hours. Solar kettles also tend to get hotter than solar cookers and can in certain instances a modified design can be used for cooking as well.

  More recently Patrick Sherwin took solar thermal technology aligned with the evacuated tube concept to a new level with his GOSUN solar stove design Using evacuated tube technology he has developed a cooker that is easy and simple to load, that functions remarkably well and can reach temperatures of 550°F and in many instances cook a meal to completion in 20 minutes.

 

This device is portable, relatively small, lightweight (3.5 lbs/ 1.5kg) and actually quite sophisticated for a solar cooking device. In addition thanks to the compounded effect of parabolic reflection, evacuation (for its remarkable insulating properties) and the Greenhouse effect, this device is able to keep food hot literally for hours on end.

  This solar cooker includes a Pyrex evacuated tube cooking chamber, two parabolic reflectors that also serve to protect the tube, a horizontal cooking tray with a handle for getting food in and out of the cooker, a carrying handle that becomes a set of support legs which can be used to adjust the tube to face the sun in any position along two axis.

  The actual evacuated tube oven is made of glass and comes with a 2 year warranty. The rest of the package is guaranteed from manufacturing defects for one year.

 

  The Navitron’s C-zero Solar Kettle/cooker is a kettle designed and developed by Navitron Ltd of Oakham. Described as one of the most efficient kettles in the world it similarly runs off evacuated solar tube technology, uses no electricity whatsoever by running exclusively off solar energy, has a capacity of 2 litres, takes about 3 hours to reach boiling point

starting at ambient temperature and retains heat for a disproportionately long time, taking in excess of 15 hours to cool right back to ambient temperatures.

  Another variant is the Solar Billy which is also a very similar design which also uses evacuated solar principles to harness the solar energy from the sun needed to heat the kettle. This kettle takes between 30 minutes to 3 hours to boil water and will still heat up, albeit slower on an overcast day because the embedded vacuum tubes absorb infra-red rays.

  Parabolic solar cooker

  The parabolic solar cooker is arguably the Rolls Royce of solar cookers. Unquestionably the most sophisticated and most effective variant of solar cooker, these are also the most expensive, because ultimately technology comes with a price tag.

  Equipped with all the bells and whistles, this type of solar cooker cooks as well as a conventional oven, and in certain instances even better. On the downside a parabolic solar cooker is a more complex design which requires a higher level of requisite skill to construct, and consequently is less aimed at the lower end of the market and is more targeted at the commercial and upper end of the potential solar cooker demographic user profile.

  It is also a physically bigger, more cumbersome and less mobile design compared to the other small solar cooker designs.

  The Merriam-Webster dictionary defines the word “parabolic” as of, having the form of, or relating to a parabola, motion in a parabolic “Parabola” is defined as a plane curve generated by a point moving so that its distance from a fixed point is equal to its distance from a fixed line: the intersection of a right circular cone with a plane parallel to an element of the cone, or alternatively something bowl-shaped (as an antenna or microphone reflector).

 

In terms of the mathematics of the parabolic curve the formula is f = / where f is the focal length of the parabolic cooker, x is the radius of the parabolic cooker and a the depth of the parabolic cooker.

  To determine the focal length practically first measure the width of the cooker from one end to another. This measurement is the diameter and needs to divided in two to establish the radius. Next measure the depth of the cooker from the centre of the cooker to a point level with the outer periphery of the dish.

  For example if the diameter of a parabolic cooker is 80 cm and the depth is 30 cm then the focal point is (4x30)=13.3cm.

  The reflector is essentially the parabolic design. It resembles a satellite dish, is concave in shape, normally manufactured out of Styrofoam or an alternative robust plastic derivative and is positioned underneath the cooking pot. In certain instances where people make their own parabolic cooker they actually use an old discarded satellite dish as the fundamental structure.

  The parabolic reflector is supported by a circular or triangular flat base. Certain models are fairly manual in terms of the operation and have to be physically moved to track the sun whereas other models have a rotating handle and base which can pivot to track the sun.

  The surface of the parabolic reflector is lined with highly reflective material such as aluminum foil (shiny side facing the sun).Fundamentally a parabolic cooker uses a reflective surface in a parabola to focus the sunshine.

 

  When a parabolic-shaped solar cooker is pointed at the sun, the solar energy generated from the sun is reflected onto a central point known as the focal point, similar to the focal point of a magnifying glass. The cooking pot is positioned on a frame just marginally above or at the focal point, in the center of the reflector.

 

Certain designs have the cooking pot frame independent of the cooker whereas with others this assembly is part of a common assembly that also supports the parabolic cooker itself.

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Funktionsschema_mit_Sonne2.jp g Author: Stephan Zech, Sun and Ice

  The reflected sunlight from the focal point is concentrated into a small point where accelerated molecule vibration takes place, causing excessive

heat which moves upwards and makes contact with the base of the cooking pot, which heats the pots and cooks the food.

  There is no insulation or greenhouse effect and there is no box or plastic bag involved. The entire dynamic is solar reflection. The excessive temperatures achieved by these parabolic cookers also allow the user to grill or fry food using an appropriate cooking utensil.

  Most domestic reflectors are not more than 5 feet in diameter. The cooking pot with food is positioned on a metal frame with a flat base on either side. The frame is positioned independently of the reflector, with the pot on a central rack just marginally above the focal point. Similarly to other solar cookers the pots should be black pot-bellied, or steel with a black porcelain coating or enameled pots with a tight-fitting lid.

  Most parabolic solar cookers can attain temperatures of 465°F (240°C) fairly quickly and as a consequence can cook fairly quickly, although most designs require frequent adjustment to optimize the solar energy from the sun (normally at least every 30 minutes or so), which necessitates a high level of supervision.

  These excessive temperatures also require the food to be stirred from time to time to avoid burning (the other types of solar cookers do not require frequent stirring and in most instances do not require any stirring whatsoever).

  A parabolic cooker left unattended can lose the focal point with a consequent fall off of cooking efficiency. Most foods can be cooked a lot

faster and a lot earlier on a parabolic cooker compared to other solar cookers.

  Due to the highly reflective nature of a parabolic cooker, it is important to use a pair of good quality sunglasses with appropriate UV protection to avoid damaging your eyes.

  Similarly when your cooker is not in use, it is advisable to cover it to avoid the cooker temporarily blinding any incidental passerby’s with reflected sunlight or heating up unnecessarily and causing a fire hazard (there have been numerous historic incidents of unattended parabolic cookers inadvertently setting an adjacent wooden shed or similar structure on fire).

  When dirty clean the parabolic reflector with a cleaning cloth and warm, soapy water. Be vigilant not to scratch the surface at all as this will reduce the efficiency of the reflector.

  Industrialized solar cooking using parabolic solar cookers is a concept and movement that appears to be slowly emerging from an extended period of hibernation.

  In much the same way that the global addiction to fossil fuels finally appears to be beginning to wane, the global realization that there might be alternative, renewable energy alternatives to conventional cooking using electricity, also appears to be very slowly gaining some impetus, in particular when it comes down to the concept of industrialized solar cooking.

 

Not that any of this would come as any surprise to Wolfgang Scheffler, on the contrary he is without question one of the early pioneers of industrialized solar cooking, in particular when it comes down to using his own invention, the Scheffler Parabolic Solar Cooker.

  This solar cooker is arguably the most well-known parabolic solar cooker design today. Developed in the early 1980s by Wolfgang Scheffler, he has gone on to focus most of his work in India where he still has a strong association to this day.

  He initially developed a parabolic fixed focus reflector and in typical altruistic fashion made his technology freely available to the good of humanity, allowing people to duplicate and even adapt his original designs.

  A feature of this Scheffler Parabolic Solar Cooker design has been its development in industrialized solar cooking applications globally, in particular with large bakeries and community kitchens.

  The function format is basically the positioning of several of the parabolic reflectors outside in the open, normally on the roof of the kitchen or in close proximity to the kitchen. The Scheffler Parabolic Solar Cookers then collectively function to receive and reflect the sunshine and in doing so function either indirectly, by aggressively heating water in water storage containers thereby inducing boiling and steam production.

  The steam is then directed and piped into the kitchen where it is utilized as energy to cook. An example of this form of cooking structure is the Tirumala temple in the southern Indian city of Tirupathithat.

  Alternatively the sunshine is directly reflected onto various solar cooking pots or solar cooking utensils which act as a catalyst to the subsequent solar cooking process. The reflectors are designed to maximize the solar energy by tracking the arc of the sun throughout the daylight hours.

  The specific design principle used by Wolfgang Scheffler is that the parabolic reflector rotates whilst reflecting the sunshine in a fixed direction as dictated by a heliostat. The consequence is a concentrated ray of sunshine which is directed into the kitchen where a downstream reflector redirects the concentrated sunshine onto the bottom of the solar cookware, thereby inducing heat and cooking.

  The solar bowl concept that exists in Auroville, India, is probably the best known solar bowl concept globally. Whilst it is similar to the parabolic solar cooking concept, it takes the scalability to a complete new level. Conceptually it functions to initially harvest the sunshine via a large spherical, concave mirror and thereafter concentrate the sun’s rays on a boiler with water.

  Essentially the design is that of a huge spherical dish 15m in diameter (which is similar but not exactly the same as a parabolic reflector) positioned on the ground. The inbound sunshine is captured and concentrated back upwards, At the focal point of the reflection is a cylindrical boiler.

  The boiler is designed to automatically track the position of the sun, thereby optimizing the reflection of the concentrated sunshine and consequent heat (a temperature of in excess of 570F°C (300°C) can be

generated), thereby heating the water internally and inducing and subsequent steam production.

  This steam then drives the cooking process in the kitchen, with in excess of 2000 meals a day being achieved. In essence the bowl serves as a solar concentrator to harvest the solar energy from the sun. Surprisingly despite the consistent and well-documented success of the solar bowl industrial concept, the design remains fairly isolated in actual solar cooking application with only India having truly successfully embraced this particular approach.

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Horno_Solar_Casero.JPG Author:

  Hybrid solar cooker

  Essentially hybrid solar cookers personify a concept that endeavors to provide the best of both worlds. These solar cookers are essentially a box solar cooker designed with a conventional electrical heating element which compensates for weather conditions where the box solar cooker is either unable to perform or potentially performs poorly.

  Probably the most widely used model globally is the Tulsi-Hybrid Solar In this design the electrical heating element functions in overcast, rainy conditions or in the evening in the absence of sunlight.

  This increased functionality of course comes with an increased price tag and the hybrid cookers are more targeted at the first world users. These models can function either exclusively as a solar cooker, exclusively as an electrical cooker or a combination of the two.

  When used as a combination the cooker is designed to cycle on and off electrically utilizing the in-built two setting thermostat that automatically maintains the internal cooking temperature to a predetermined temperature.

  When the Tulsi-Hybrid Solar Oven is used as a true hybrid the electrical usage is approximately 25 percent that of a conventional oven. The other advantages of the Tulsi-Hybrid Solar Oven are that the design has a robust, one-piece reflector panel, and can be packed away into a compact suitcase size making for easy storage and making it fully portable.

  Another variant of hybrid solar cooking technology is the tripod hybrid solar grill which was designed by Tim Norton of Florida, USA in 2006. This technology interfaces with parabolic solar cooking technology and consists of a movable parabolic reflector positioned in the bottom of a tripod with a grill surface positioned above the parabolic reflector.

  The cooking pots and pans are positioned on the grill. The parabolic reflector is a satellite dish lined with a highly reflective layer of aluminized Mylar and a polyurethane protective layer with an aperture of 33 inches and a focal length of 18 inches.

  Food can be baked, fried, boiled, broiled, stewed and even smoked using this solar grill. Under favourable conditions cooking temperatures of 450°F (230°C) can be achieved.

  In unfavourable solar weather conditions, the parabolic reflector can be removed and the grill can be used with most conventional fuels (wood, gas, charcoal, propane, electricity etc.).

  The structure is relatively stable even in high wind conditions due to the wide base and low center of gravity.

 

  Photo courtesy of Sun BD Corporation at http://www.sunbdcorp.com

  Sean McGreevy has a slightly different conceptual interpretation of a hybrid solar grill with his Helios design. Helios is a conceptual solar grill that uses the energy from the sun to grill food.

  It similarly utilizes a parabolic principle by using a parabolic dish to concentrate the sun’s energy on the solar receptor, positioned at the exact

focal point of the parabolic reflector, where the energy is then subsequently transferred to the heating coil within the grill and is converted to heat energy.

  It features a unique cantilevered design that safely keeps the reflective surface away from the user. As well as a collapsing parabolic dish to neatly store the unit upright. On overcast days or in the evening when solar cooking is not possible there is retractable plug is stored in the base as a backup electricity energy source.

 

  Solar vacuum tube oven

  This concept is basically a modified design of the Solar Kettle-Thermos Flask (SK-TF) concept utilized to cook certain foods. The principle is the same and the magnitude simple proportionately larger with the device characterized by a 12cm outer diameter and a 10 cm inner diameter.

  In principle this solar vacuum tube oven (SaVeTao) bakes, cooks and even makes autoclaving possible. Similarly to the SK-TF, the thermos vacuum tube keeps previously heated water and food hot insulated through the night with its sustained vacuum insulation properties, allowing a hot, ready to serve breakfast first thing in the morning, even before sunrise.

  In this respect the SaVeTao outperforms the other conventional solar cookers that require at least some form of sunshine to function.

  Funnel solar cooker

  A funnel solar cooker is simply a less sophisticated variant of a basic panel cooker design. As opposed to having various distinct panels forming part of a network of panels surrounding the cooking pot, the funnel cooker is simply a complete funnel designed with the funnel inversely flared.

  In other words the open end of the funnel closest to the sun is open wide and flared inwards down to a closed bottom, where the cooking pot is positioned.

  The narrow closed end is normally positioned in a bucket or box or equivalent receptacle to provide stability and anchorage. Essentially the funnel-shaped solar cooker concentrates the sunlight towards the bottom of the funnel, directed into a cooking pot.

  The cooking pot (the usual solar cooking pots are recommended, preferably black in colour with a tightly fitting lid) is encapsulated in a plastic bag (high density polyethylene construction, preferably a minimum of 50 micron) trapping the heat and inducing cooking, an effect that personifies the greenhouse effect.

  Some people prefer to place a small block of black-painted wood underneath the pot and to blow some air into the plastic bag to enhance the cooking effect.

 

Similarly to the panel cookers the solar funnel cookers are safe, portable, inexpensive, do not require a great deal of skill to build and are effective in cooking food.

  The actual funnel can be constructed out of most simple materials but a thick cardboard will suffice, lined with a basic aluminum foil, with the shiny side on the outside.

  A very basic funnel cooker is commonly constructed from the windshield shade (dashboard protector) of a car, and in an emergency a temporary model can literally be set up in a matter of minutes.

  Once the cooking is complete the windshield is simply disassembled and folded back up to function on the dashboard of the car.

 

  Photo courtesy of EBKauai at http://www.flickr.com/photos/13470115@N08/4876830913/

  Hot Dog Solar Cooker

  A solar hot dog cooker is a fun, popular and easy way to use a solar cooker that is particularly popular with anyone who enjoys a fresh and warm hot dogs, nicely cushioned in a fresh bun with melting butter and maybe just a touch of mustard. Whist these solar cookers are not commonly commercially produced, most are home-made.

  In principle the hot dog cooker emulates the parabolic reflector functionality in that the meat skewer is carefully positioned at the focal length of the parabolic reflector, therein receiving maximum focused sunshine. The reflector is designed in a parabolic curve manufactured normally out of metal, wood or cardboard and lined with some form of highly reflective material, for example aluminum foil (with the shiny side facing outwards towards the sun).

  The skewer is positioned on a small assembly of sorts (usually anchored with side supports on the body of the cooker, at the apex of the curve) positioned horizontally over the reflector. Usually the skewer will have a small handle to enable the solar chef to gradually but progressively turn the skewer thereby turning the food and ensuring an even cooking application without burning the food. Whilst the name solar hot dog cooker implies that only hot dogs are cooked over the reflector the truth is any suitable foodstuff can be cooked in this fashion, for example marshmallows, chicken, fish, seafood, meat and even certain vegetables.

 

Solar hot dog cooker plans are fairly readily available online and the design is fairly easy to construct, on condition you fabricate an accurate parabolic curve, and that your focal curve is correctly determined and meets flush with the skewer, optimizing the concentrated sunshine. Generally the focal curve should be somewhere between 6-15 inches above the surface of the reflector.

 

  Photo courtesy of ncyg46 at http://www.flickr.com/photos/ncyg46/4555347551/

Solar Cooking Pots

  Ideally solar cooking pots need to be constructed as such that the pot absorbs and retains as much heat as possible. Research has clearly demonstrated that dark pots, in particular black pots, work the best in this regard.

  If dark pots cannot be sourced, an appropriate sized and constructed pot can be darkened either with food-grade black spray paint (care must be exercise with respect to the potential toxicity of vaporized paint) or in extreme circumstances, soot from a fire. In certain instances light coloured pots and pans can be wrapped in dark paper or cloth bags.

  Another alternative to blacken a pot would be to powder coat it black and bake it to establish colour permanency. In this process the powdered paint is electrostatically charged and sprayed onto the pot.

  The pot is then positioned in a hot oven and the powder particles melt and coalesce to form a permanent, continuous film that will not melt when exposed to subsequent heating.

  During the curing process in a hot oven a chemical cross-linking reaction is triggered at the tipping curing temperature and it is this chemical reaction which gives the powder coating its permanency.

 

  In terms of conventional solar cooking pots black enameled bellied pots work well as to black enameled cast iron pots and black steel porcelain pots and baking pans.

  Another important feature is the pot needs to have a tight-fitting lid to minimize heat loss and to retain moisture, which ensures the food does not dry out.

  Pots of thin material augmented with a slightly shallow design heat up faster compared to deeper pots with a thicker surface (but also conversely will not retain the heat for as long as the pots constructed from an equivalent but thicker material).

  Metal pots tend to heat faster than earthenware or ceramic pots. Cast iron pots are heavy, solid pots that are slow to heat initially but do retain heat for longer periods.

 

  Tempered glass jars can also be used although once again these will function a lot faster if the jar has been blackened. In certain instances a glass jar will need to be vented to avoid excessive steam pressure build up.

  In some isolated rural areas gourds (calabash) have also been successfully used as solar pots although the gourds need to be dried out in the sun for a number of months after having ripened and harvested and then properly cleaned out and prepared. A small lid (usually constructed from glass) is then fashioned for the top of the gourd. Similarly the gourd will work best if properly blackened on the outside.

 

Aluminum foil can also be used but will only cook properly if blackened on the outside. Aluminum baking pans also work reasonably well.

  Whilst there appears to a lack of definitive research on the issue of cooking food in a solar oven using a blackened tin, this practice should be avoided in light of the debate of the possible uptake of metal compounds into food cooked in tin cans.

  Recent research has also clearly demonstrated that using a black finned pot improves the speed and efficiency of solar cooking. The external fins effectively increase the heating surface area which accelerates the heating of the food in the pots.

  Dark Pyrex pots can also be used although the heat conduction and transfer properties are not as efficient as the enamel and cast iron equivalent pots. When using a lidded baking pan it is recommended a small stainless steel grid platform be used on the bottom of the pan which ensures when food, especially protein, is cooked the fat drips down on to the bottom of the pan and can be discarded before serving the meal.

  An excellent selection of pots and pans can be purchased off the Solar Cookers International website at www.solarcookers.org (or sourced from their regular Solar Cooker Review newsletter).

 

  Solar cooking pots and pans are available in different sizes and different constructions.

  In terms of general appearance there are probably two broad categories of solar cookware, there are the genuine spherical solar pots which vary in size but start at about 6 inches (15 cm) in diameter and 5 inches (12 cm) in depth (height) and then are available in progressively bigger size formats with similar diameter and depth proportions. These solar cooking pots have a thin, flat, slightly domed-shaped lid with a handle.

  Alternatively there are the solar cooking pans which tend to be rectangular or oval in shape. These solar cooking pots also come in varying sizes, shapes and proportions and start as small as about 10 inches (25 cm) long

and can get a lot bigger, as long as 15 inches (38 cm) or even slightly longer.

  The depth tends to vary between 4-6 inches (10-15 cm). These solar cooking pans either have a thin, flat, slightly domed-shaped lid with handles on either side or a top handle or both, alternatively the lid is a double volume lid that fits snugly into the bottom pan and in some instances does not have handles.

  It is possible to become mired in technical detail in determining the appropriate construction of the various solar cookware variants, with various viable materials available on the market, although generally the preferred construction is thin enamel (steel coated with enamel) which tends to promotes faster cooking.

Advantages of Solar Cooking

  There are numerous and varied benefits of using solar cooking. The obvious benefits are best summarized as the following:

  First and foremost no electricity is required. There is a once-off, small cost in acquiring the solar cooker and thereafter no overhead cost implications. In addition there is reduced cooking in the kitchen which reduces the pressure on air conditioning and refrigerators.

  Most solar cookers are easy to use and do not require an advanced level of technical skill. A basic education on how to use the solar cooker is necessary and thereafter the user can use the cooker day in and day out on a regular basis. In many instances a solar cooker (for example a funnel solar cooker) can also be very easily and very quickly assembled and built, often using basic local materials.

  Often if a community embraces the concept a direct spinoff is employment opportunity for women who become involved in the assembly and construction of the solar cookers on a commercial or semicommercial basis..

  Slow-cooking The process dynamic is slow cooking. Cooking with a solar cooker is like a combination between cooking with a pressure cooker and cooking with a slow cooker. The food cooks properly over an extended time and due to the low thermal flux dynamic food does not burn.

 

Despite the longer cooking times in comparison to conventional cooking, solar cooked foods retain and preserve the vitamin and nutrient content of the food as well as, or even better than foods cooked by conventional methods.

  With certain carbohydrates extensive cooking can eventually lead to a breakdown in food texture and consistency. Fish can also eventually dry out if cooked excessively in a solar cooker.

  No fuel The raw material is sunshine which is abundant and free (although not necessarily always available). As a consequence there is no fuel requirement which reduces and potentially eliminates deforestation and all related activities in the region such as smoke-pollution.

  A secondary benefit of not having to collect fuel is that there is no need to walk long distances to find and retrieve fuel, for example wood. It has been recently extrapolated that one solar cooker saves approximately the equivalent of 2 tons of trees per annum.

  The reduction in the need for fuel allows the community to concentrate on other activities and improves the safety and security of the individuals who were previously tasked with the collection process, as they are no longer exposed to the risk of attack outside their immediate area of residence.

  In terms of the macro environment greater reliance on sunshine and reduced reliance on burning fuel translates into a reduced greenhouse effect, reduced reliance on fossil fuels, an improved contribution to reducing global warming and a lower carbon footprint loading.

  A further specific benefit is the reduction of black carbon emissions. Black carbon is a consequence of incomplete combustion of fossil fuels and biofuels and is particularly prevalent in Africa as a consequence of open fires. Black carbon emissions are postulated to be disproportionately detrimental to the greenhouse effect and particularly severe on human health.

  Water sterilization and Water can be heated and pasteurized thereby sharply reducing the risk and occurrence of water-borne diseases such as cholera, enteritis and diarrhoea.

  In areas where communities live in close proximity to water the use of a solar still, be it a domestic model or a commercial model, can generate pure, uncontaminated water on a daily basis.

  Health and Less utilization of open fires translates into a lower fire risk. Less smoke generation reduces the risk of lung, upper-respiratory, heart disease, eye disease (it has been postulated that people are exposed to a higher risk of Glaucoma when exposed frequently to toxic smoke from open fires) and in general premature death (smoke pollution is thought to be responsible for over 1 million deaths each year). Reduced supervision results in a more productive lifestyle.

  Vitamin Whilst we ingest small quantities of vitamin D in our diets most of the vitamin D is produced in our bodies on exposure to sunlight. Vitamin D, sometimes referred to as the sunshine vitamin, maintains the balance of calcium and phosphorus in the body, which is essential for healthy bones and teeth.

  Research also indicates that vitamin D functions to reduce various illnesses, including osteoporosis and certain autoimmune and infectious diseases. Whilst the slow solar cooking better preserves all vitamins, the general outdoors exposure to sunshine whilst engaging in solar cooking can only serve to better fuel and unlock our metabolism with vitamin D.

  Certain of the makes of solar cookers, for example the box and panel solar cookers, are light weight and can be easily folded up into a compact unit and transported. In many instances the solar cookers weigh less than 11lbs (5 kg).

  Most commercial solar cookers are assembled and constructed from robust materials which if properly cleaned and maintained should last for an extended period of time, possibly even a lifetime. In addition most solar cookers have very few moving parts and require minimal repair or maintenance.

Disadvantages of Solar Cooking

  Night By and large solar cooking is restricted to day time cooking due to the necessity of sunlight, which makes it problematic if there is a need to cook a meal in the evening.

  Cooking In most instances solar cooking takes a lot longer than conventional cooking. This form of cooking also requires at least some form of limited supervision where it is necessary to adjust the solar cooker to follow the arc of the sun to optimize exposure to sunlight.

  The availability of sunshine is critical to the functionality of solar cooking. Limited or no sunshine translates into limited or no solar cooking. Certain climates simply do not generate sufficient sunshine for solar cooking to be feasible on a regular, ongoing basis.

Solar Dehydration

  Solar dehydrators function to extract moisture from foods while preserving color and flavour. Essentially the dehydrator reduces the water content in the food and in doing so the food is preserved for extended periods of time. Bacteria require a certain minimum moisture content to function. This content is referred to as water activity. Below a certain water activity the bacteria is inactive. Dehydration of food reduces the moisture level to below these levels.

  The process of dehydration in foodstuffs is simply that of reducing the internal water content and in certain instances the intracellular water content of the food. Effectively when heat is applied to the food it induces evaporation of the water, which results in the water within the food first migrating to the periphery of the food, and then undergoing a phase change from liquid to gas, in other words water to water vapor.

  The reduction in water content results in reduced water activity with a consequent reduced growth of microorganisms and certain natural processes like ripening or putrefaction. Each microorganism has a maximal, optimal and minimal water activity at which it grows, and generally bacteria require more moisture than yeasts and yeasts require more moisture than molds.

  Dehydration of foods is an excellent method of preserving the foods and is practiced extensively in the modern age. Solar dehydration is using the sunshine and consequent heat of the sun to induce evaporation and dry the food.

 

Solar dehydration can sometimes be limited to climates with hot sun and dry atmospheric conditions and tends to work best with certain select food types, for example prunes, figs , apricots, pears and peaches, and in the case of meat, beef jerky and certain fish species.

  Whilst in certain instances this can literally be achieved by placing the foodstuff in the direct sunshine on a container or large tray and turning the food on a regular or semi-regular basis, the technique is generally facilitated by using a solar dehydrator.

  A classic example of solar dehydration using a simple tray technique is the kapenta fishing industry in Lake Kariba in the Zambezi Valley in Zimbabwe, where 20 tons of kapenta (Tanganyika sardine) are caught each year during the evening. The small fish are then mixed with coarse salt (1lb salt for 12 lbs of fish) on the fishing boats and subsequently transported to land where the kapenta are sorted and placed on large, flat trays and dried in the sun. The fish remain an extremely important source of protein for the local population.

  A solar dehydrator, also referred to as a solar dryer, is a solar appliance that is designed to dry foods using the power of the sun and nothing else. Solar dehydrators function to extract moisture from foods while preserving color and flavour.

  The solar dehydrator design is simply a top, horizontal, square box which functions as the primary drying compartment. This horizontal box, the solar collector tray, consists of multiple layers with air flowing through driving the drying process. The top of the box is covered with a fine screen to allow for air flow but to also keep insects out. The food to be dried is spread along the bottom of the box in one layer.

 

  Photo courtesy of Wikimedia Commons at http://commons.wikimedia.org/wiki/File:Sonnendorrer_solar_food_dehyd rator.JPG Author: Claudio Tennie

  Below the horizontal box is a secondary box, usually painted black on the inside which angles down towards the ground. The top of this box is covered with plastic to enhance the greenhouse effect. This box functions to transfer more warm air to the food being dried.

  The bottom of the ramp should have vents to allow air to enter and similarly should be covered with a fine screen to keep insects out. The solar dehydrator should be exposed to full sunlight that will allow the sunshine to enter the heating box through the plastic. The back backing warms up the air which moves up and enters the drying box. The moisture within the food is gradually but progressively dissipated when exposed to

continual hot air. The hot air ultimately passes through and exits the dehydrator through the top fine screen.

  Once adequately dried, store the food in clean, sterile plastic bags at between 40-70°F (5-20°C). The food should be fairly brittle once properly dried. If you want to apply a degree of science to the process you could analyze the actual moisture content of the food, per individual food type or category, and through a process of trial and error you could determine exactly what your targeted final moisture contents should be per individual food type and what the normal solar application would be to achieve those levels.

How to Build a Solar Cooker

  Building a Funnel This might not be the most sophisticated or even the most effective solar cooker but it is unquestionably one of the easiest, quickest and cheapest to make. In fact the basic design lies dormant in most vehicles, ironically seeing the light of day frequently but never quite realizing what could be described as the full solar potential. Enter the simple windshield shade.

  To metamorphosis the solar funnel start by unfolding the windshield so it is fully open with the reflective surface facing upwards, towards you (the more reflective the surface the better). Check that the reflective surface is clean with minimal scratches, tearing or any other blemish.

  You will need to secure the left hand side to the right hand side to form a funnel so ideally you require some form of sticking material to ensure the funnel shape will hold it form. You can use a variety of components from duct tape, to Velcro, clips or pegs or even staples. For Velcro to ensure some form of permanence it would be preferable to hand sew some Velcro strips on the two edges.

  Now fold the windshield inwards and secure the two edges flush together to form a funnel, ensuring the most reflective surface is facing inwards. Position the base of the funnel (closed end) in the mouth of a tight-fitting bucket or box to achieve stability.

  Position an appropriate black cooking pot on a stable base of some sort on top of the bucket or box. The base can be a cooking grid, a rack or even a square or rectangular piece of wood, preferably painted black. This base must be very marginally larger than the outer edges of the top of the

bucket or box (in other words it must overlay these edges slightly) to provide stability.

  The base and the pot with a tight-fitting lid (with the prepared uncooked food inside) must be put into an appropriate plastic bag, for example an oven bag is perfect. Either manually blow some air into the bag to give it some body or use a small inflatable air pump. The additional air helps to accentuate the greenhouse effect whilst heating. The pot plus base in the plastic bag is placed at the bottom of the funnel.

  The funnel cooker is now orientated to take full advantage of the sun. Whilst cooking, check the cooker relative to the arc of the sun every hour. If necessary move the cooker slightly to endeavor to maintain full exposure to the sun.

  Building a Box Initially you will need to source two cardboard boxes, one large box and a slightly smaller box that fits reasonably snugly into the larger box, with a difference of about 2 inches (6 cm) between the inner wall of the big box and the outer wall of the internal box.

  Try and select two boxes that are similar in proportion so that all four sides of the small box when fitted inside of the big box are more or less equidistant.

  The smaller box will in effect be the inside of the solar cooker, so select this internal box so that it is marginally bigger in area than the collective size of the cooking devices you will be using and is about 1inch (3 cm) higher. The inner box should be about 1 inch (3 cm) lower than the outside box.

  Err on the side of caution in terms of the thickness of the boxes, as the cooker will need to be reasonably robust in design.

  Do not select boxes that are paper-thin. The boxes can either be square or rectangular in shape. The recommended minimum size for the inner box is about 16x14x10 inches (40x35x25 cm) from a length x breadth x height/ depth orientation).

  Separate the two boxes and initially concentrate on the small box. Using a pair of scissors or a sharp knife cut the top flaps off the small box. Be careful not to cut yourself.

 

A pair of hardware gloves is recommended for the cutting work. Cover all the inside surfaces of the small box with aluminum foil, ensuring the shiny side is facing upwards.

  Either paint the bottom of the box with back, non-toxic paint or alternatively line and secure it with black construction paper. You can ensure the foil is secured using either glue, clear tape or a staple gun. Seal all the bottom and side seams on both boxes using duct tape.

  Now turn all the top flaps of the large box inwards and horizontal, in other words close the big box.

  Position the small box on top of the big box equidistant from all the sides and using a black marker pen outline the bottom dimensions of the small box on the flaps of the big box.

  Remove the small box and carefully cut out the markings, so that effectively you cut a square hole into the top of the big box allowing the small box to now tightly fit into the big box.

 

  Position the small box in the big box and then fill the four sides up with some form of appropriate insulating material, either more cardboard or crumpled newspapers work well (or a combination).

 

Ensure there is also about 1-2 inches (3-6 cm) of insulation between the bottom of the big box and the bottom of the small box. Tape the flap down with duct tape. The small, internal box should now sit flush in the bigger box and the height of both should also be flush.

  Now design a reflector panel to facilitate heating. Measure the outer dimensions of the box and add about 3 inches (8 cm) to the length. Find a length of cardboard similar to these dimensions and of the same approximate construction of the two boxes and cut it exactly to size.

  Cover the one side of this piece of cardboard with aluminum foil with the shiny side up, in other words to enable the shiny side to be exposed to the sun. Secure the foil to the cardboard using either glue, clear tape or a staple gun.

  Using the leverage of the 3 inch (8cm) overlap, secure the reflector to the side of the cooker. Using a staple gun to secure this reflector will provide some stability and permanence. You can further support the reflector by attaching a piece of nylon or string on either side to the reflector and then secure this to the main body of the box.

  Cut a piece of reinforced glass approximately 1 inch (2.5 cm) longer and wider than the length and width of the outer box. Carefully buff and smoothen the outside edges of the glass to enable safe handling of the glass. This piece of glass now functions as the lid of the cooker.

  Position the cooker so it is fully exposed to the sun, with the reflector at the back of the cooker reflecting sunshine down onto the cooker. Prepare the food in appropriate black cooking pots with tightly fitting lids. Place the pots in the internal box. Position the glass lid over the box so it fits

flush with the top of the box and so that the box is fully covered, trapping the air inside.

  Building a Pizza Box A variation on the box cooker is using a simple, disused pizza box. Source a clean, unblemished pizza box. Using a tape measure or ruler and black marking pen, measure and outline a 1 inch (2.5 cm) border on all four sides of the top of the pizza box. Now carefully cut through on three of the sides, effectively making a flap. Fold the flap up and backwards. The uncut line now naturally forms a crease.

  Measure and cut a sheet of heavy-duty aluminum foil (or equivalent reflective material, even thin mirror paneling will work) for the flap. Glue the aluminum foil to the underside of the flap ensuring the shiny side is facing upwards. This flap will act as the reflector.

  Measure a piece of thick (preferably at least 80 microns), transparent polyethylene plastic and fit this to the top of the opening that has been formed by cutting open the flap. Secure the plastic by taping it with duct tape to the underside of the lid of the pizza box. Ensure the plastic is tight with no creases and that the lid is effectively air-tight, to enable the heat to be trapped.

  Now measure and cut another piece of aluminum foil to fit snugly on the bottom of the pizza box. Glue this into place and then measure and cut a piece of black construction paper to fit over the top of the aluminum. Secure this using tape.

  To operate the solar pizza cooker place your food in an appropriate shallow, black, lidded container on the base of the cooker. Put the top of the box over the bottom, thereby closing the box off.

  Expose the box to full sunlight with the top on and ensure the reflector flap is correctly positioned to achieve maximum reflection through the plastic into the box onto the food container. The reflector flap needs to be held in place using an appropriate device, for example a wooden stick or the equivalent.

  Whilst the shallow dimensions of the box restrict the food types that can be cooked in a pizza cooker there is still a variety of food types that will work, including cooking a raw pizza.

 

  Photo courtesy of the candlequeen44 at http://www.flickr.com/photos/nonnie44/2972147975/sizes/z/in/set72157608366876923/

  Building a Hot Dog This hot dog solar cooker is essentially a type of embedded parabolic cooker designed specifically for hot dogs, chicken or meat kebabs or any food that can be cooked using a skewer applied to heat, including marshmallows.

  Start off by sourcing a rectangular cardboard box, the longer the better as this personifies the parabolic efficiency of the cooker. Calculate an appropriate parabolic curve (in other words a perfect bowl-shaped curve that is equidistant on both ends, in effect both ends of the curve are a mirror image).

  Design the curve so that the bottom centre of the curve is about two-thirds from the top of the box and the focal length is about 6 to 12 inches. Using a black marker pen draw the curve on the top outside of both the long sides of the box, ensuring the dimensions and slant of the curve is identical for both sides.

  Very carefully and slowly and following the marked line, cut out the curve on both sides of the box. Measure and cut out a length of poster board to fit snugly on top of the box in the curvature that has been cut out.

  Fit the poster board to fit flush with the top of the box and secure the poster board using tape. Measure and cut out a piece of heavy-duty aluminum foil to fit on the surface of the poster board.

  Apply glue to the upper surface of the poster board and glue the aluminum foil exactly on top of the poster board, shiny side facing upwards,

ensuring the foil is smooth and even and has no trapped air bubbles.

  Using a mirror on a sunny day above the reflector and moving it up and down ascertain exactly where the focal point is. Design the skewer stand to be positioned exactly at this height. Now select and measure two study pieces of cardboard side supports and secure these to the sides in the centre of the cooker.

  Cut a hole in one of the supports and a notch in the top of the other support. Fit a home-made skewer (piece of wire) through the hole and rest the other end in the notch. Both the hole and notch must be exactly the same height. The hot dogs can now be skewed and cooked.

  Building a Parabolic Building a parabolic solar cooker is a challenging and detailed project. This cooker is a more complex design which requires a higher level of requisite skill to construct, and requires an advanced level of DIY skill.

  One of the most common techniques is to utilize a disused satellite dish. The advantage of this approach is that the perfect parabolic structure already exists and simply needs to be modified and reincarnated as a solar cooker.

  When selecting a satellite dish, attempt to use a dish where the curvature allows for the focal point to be approximately a third of the way down from the top of parabola. This position tends to maximize heating and wind protection.

  Calculate and physically verify the focal point by moving a mirror (alternatively use a piece of paper or cardboard) up and down the reflected light on a sunny day. Your focal point is where the circle of light is the smallest and most concentrated.

  Begin by removing all unnecessary paraphernalia associated with the satellite functionality but primarily the signal-collecting apparatus positioned at the focal point of the satellite dish.

  Once this is removed, line the inside of the dish (reflective surface) with an appropriate reflective material, for example aluminum foil (shiny side up), aluminum sheeting or flashing or Mylar anodized aluminum.

  Ensure the reflective material is not scratched or visually blemished and try and get the lining as smooth as possible. For smaller dishes you can glue the foil on but for the bigger dishes, especially the ribbed dishes, you will need to permanently secure the aluminum sheeting by cutting the material into triangular pieces, drilling where necessary and then riveting the material to the frame or alternatively securing it using tightly wound wire.

  This is normally the most time-consuming part of the process but also the most important, as a poorly reflective surface will compromise the entire functionality of the project.

  Next manufacture a pot stand frame that essentially straddles the parabolic reflector and is positioned so that the frame runs over the reflector and has a pot stand in the exact centre, with the base of the pot stand located exactly at the focal point, which allows the reflected sunlight to be concentrated exactly at the base of the cooking pot.

  Various materials can be used to manufacture the frame and pot stand, although usually simple metal, mild steel or wire is used. The pot holder must be rigid and fairly robust to support the weight of the cooking pot and food.

  The parabolic reflector must be secured at the back to a frame that adequately supports the weight of the cooker and allows the cooker to swivel to follow the arc of the sun.

 

Once complete it is a good idea to design or buy a cover for the cooker for storage purposes. Apart from keeping the apparatus clean and compact, it also acts as a safety feature, eliminating any unintended reflection which inadvertently could act as a potential fire hazard.

Solar Cooking Organizations

  Solar Cookers International

  Solar Cookers International (SCI) is a 501(c)(3) nonprofit, nongovernmental organization located in Sacramento, California. This organization was founded in 1987 by Bev Blum, Barbara Kerr, Dr Bob Metcalf and 14 other solar cooking associates. SCI has a current permanent staff of 10 and boasts a global membership of in excess of 6000 members.

  Whilst SCI’s initial focus was the distribution of educational booklets on solar cooking, they have gone from strength to strength as an organization and over the years have probably become the world’s leading authority on solar cooking.

  Although SCI’s primary focus remains solar cooking and water pasteurization and testing, their efforts remain unfaltering in partnering and networking with related agencies, organizations, governments, communities and individuals to teach the skill and spread the word on solar cooking and related activities, therein empowering and sustaining previously disadvantaged communities, in particular, (although not confined to) rural communities.

  SCI also works closely with the United Nations with respect to policy making and implementation in this area and has also hosted various international solar cooking conferences. SCI also sponsor and support the Solar Cooking Archive Wiki, a collective online database focusing specifically on solar cooking information and activities.

  Kyoto Twist Solar Cooking Society

  The Kyoto Twist Solar Cooking Society is a Canadian registered nonprofit organization located in Lund, British Columbia, Canada. Similarly to SCI the Kyoto Twist Solar Cooking Society is dedicated to spreading the word and functionality of solar cooking globally and in doing so contributing to the reduction of global poverty and the reduction of harmful greenhouse gas emissions.

  They are part of the global solar cooking community and raise funds to both support and develop solar cooking projects and initiatives globally, particularly in the developing world and through working with likeminded organizations and networks in the developing world.

  Solar Household Energy, Inc. (SHE)

  SHE was founded in 1998 as a 501(c)(3) nonprofit, non-governmental organization. The organization is located in Maryland, USA. SHE functions to serve the solar cooking community by supporting relevant market initiatives and projects. The goals of SHE are to support and promote solar cooking globally, therein reducing the harmful effects of greenhouse gas emissions.

  In 2006 SHE changed status to a 501(c)(3) public charity organization. SHE focuses on promoting the widespread and sustained usage of solar cookers in developing countries through a collective network of local entrepreneurs who are exposed to the appropriate training, education and ongoing support.

  Solar Oven Society

  The Solar Oven Society was founded by Mike and Martha Port in Minnesota. They have worked all over the world with impoverished communities introducing and promoting the concept of solar cooking. Their specific focus is developing and marketing solar cookers and over the years they have evolved from simple designs to their current robust Sport Solar oven.

  Sun Ovens International, Inc

  Similarly to the Solar Oven Society the Sun Oven International approach is to work with and optimize solar cooking using specific, extensively researched solar cookers. They were founded in 1998 in Illinois.

  Originally the Sun Oven patent was researched and developed by Tom Burns in 1986 and subsequently improved and refined with the assistance of Sandia National Laboratories. The Sun Ovens for the North American market are manufactured in Illinois whereas Sun Ovens used in other countries are largely manufactured by local plants that have been set up by Sun Ovens International.

  Their focus remains to offer a solar cooker that is manufactured from a superior quality raw material and that although maybe initially is comparatively expensive, is designed to deliver a more robust and sustainable performance in the longer term.

  ULOG

  Ulrich and Liesel Oehler originally founded ULOG in 1984 in Switzerland after originally developing their first solar cooker in 1980. An Austrian, Wolfgang Scheffler, joined ULOG in 1987 and developed the Scheffler parabolic cooker.

  ULOG is a NGO that concentrates mainly on small-scale projects and developments. They currently sell a variety of different solar cookers and solar driers, including the ‘Scheffler-type’ parabolic cookers.

  They operate globally but are most active in Europe and developing countries. Where required they also get involved in solar cooking training and education.

  EG-Solar

  EG Solar was officially founded in 1993 by Dieter Seifert and his wife Imma Based in Germany, EG Solar specializes in manufacturing a variety of parabolic solar cookers in Germany and exporting these devices all over the world. Dieter Seifert has done extensive work in promoting solar cooking to achieve legal carbon credits by reducing the emission of carbon and harmful greenhouse gases.

  Central American Solar Energy Project

  The Central American Solar Energy Project (CASEP) is a 501(c) (3) private funding operation that is dedicated to the manufacture and widespread use of solar cookers in Central America, with particular focus in Guatemala, Honduras and Nicaragua.

  CASEP was founded in 1991 by Professor Bill Lankford, originally from Fairfax, Virginia. CASEP strives primarily to empower women from the local communities to use and develop the solar cooking concept thereby reducing their dependence on fossil fuels for cooking and at the same time reducing deforestation and illness caused by open-fire cooking.

  Sunstove Organization

  The Sunstove Organization based in South Africa was originally founded by Dick Wareham and Margaret Bennett in 1990 and is dedicated to the education and supply of Sunstove solar cookers to the disadvantaged rural communities of southern Africa. Based in Johannesburg, Margaret Bennett continues to supply one of the most cost-effective solar cookers in Africa and globally.

Solar Cooking Resources

  The Solar Cooking Archive

  This is an extremely comprehensive solar cooking archive sponsored by SCI which contains everything from A to Z on solar cooking, including articles, updates, information, networking, organizations, education, newsletter, online reviews, blogs, vendors etc.

  Solar Cookers International

  The 2006 SOLAR COOKERS AND FOOD PROCESSING INTERNATIONAL CONFERENCE was hosted in Granada, Spain, from 12th to 16th of July 2006. The conference and related papers can be located at http://www.solarconference.net/index.htm

Purchase of Solar Cookers (Websites and Related Products)

    Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products)

Products) Products) Products) Products) Products)

Products) Products) Products) Products) Products) Products) Products) Products) Products) Products) Products)

 

Solar Cooking Recipes (servings for 4)

  1. Solar Breads

  Honey Whole wheat Bread

  1 tablespoon Instant yeast (check the Best Before date on the sachet) ¼ cup water 1 cup milk/ buttermilk ½ cup rolled oats 1½ teaspoons salt 2 tablespoons olive oil ½ cup honey 1 egg ¼ cup wheat germ 2 ¾ cups whole wheat flour, sifted

  Grease a black pot. Combine the yeast, milk, water, oats, salt, olive oil, honey, egg and wheat germ. Add flour and knead until smooth and elastic (about 5-10 min).Turn the dough into the black pot and put on the lid. Cook in full sun for a minimum of 2 hours.

  Whole wheat Bread

  1 cup white bread flour, sifted 2 cups whole wheat flour, sifted 2 teaspoons Instant yeast (check the Best Before date on the sachet) 2 teaspoons salt 6 teaspoons white sugar

6 teaspoons cooking oil 1½ cups water

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  Beer Bread

  3 cups bread flour, sifted 2 ½ teaspoons Instant yeast (check the Best Before date on the sachet) ½ teaspoons salt 3 tablespoons brown sugar 2 tablespoons olive oil ⅓ cup lukewarm water 1 beer at ambient temperature (avoid using a cold beer)

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and beer and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for a minimum of 2 hours.

  Corn (Mielie) Bread

  1 cup bread flour, sifted 2 ½ teaspoons Instant yeast (check the Best Before date on the sachet)

½ teaspoons salt 3 tablespoons brown sugar 3 tablespoons olive oil 1 egg ½ cup corn meal ½ cup corn flour, sifted 1 cup milk at ambient temperature (do not use cold milk)

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and egg and stir. Make a hollow in the mixture, add the milk and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for a minimum of 2 hours.

  Raisin and Nut Bread

  3 cups bread flour, sifted 2 teaspoons Instant yeast (check the Best Before date on the sachet) 2 teaspoons salt 1 teaspoon cinnamon 1 cup nuts, coarsely ground 1 cup raisins 2 tablespoons white sugar 3 tablespoons olive oil 1 ½ cups water 2 tablespoons dried powdered milk

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10

min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  White Onion Bread

  3 cups bread flour, sifted 2 teaspoons Instant yeast (check the Best Before date on the sachet) 2 teaspoons salt 1 tablespoon garlic powder 1 cup finely chopped onions 2 tablespoons white sugar 1 tablespoons olive oil ¾ cups water 1 cup milk at ambient temperature (do not use cold milk)

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for a minimum of 2 hours

  Banana Bread

  3 cups bread flour, sifted 2 teaspoons Instant yeast (check the Best Before date on the sachet) 2 teaspoons salt 1 tsp vanilla extract 1 teaspoon cinnamon 2 ripe bananas

2 tablespoons white sugar 1 tablespoons olive oil ¾ cup water 1 cup milk at ambient temperature (do not use cold milk)

  Place all the dry ingredients, including the yeast and bananas, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and milk and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  Garlic Bread

  3 cups bread flour, sifted 1 tablespoon garlic powder 2 teaspoons Instant yeast (check the Best Before date on the sachet) 2 teaspoons salt 6 teaspoons white sugar 6 teaspoons cooking oil 1½ cups water

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and stir. Make a hollow in the mixture, add the water and stir thoroughly for 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  Blueberry Zucchini Bread

 

3 cups bread flour, sifted 1 tablespoon cinnamon 2 teaspoons Instant yeast (check the Best Before date on the sachet) 1 teaspoon salt 1 cup fresh blueberries 2 cups shredded zucchini 3 tsp vanilla extract 2 cups white sugar 1 cup olive oil 3 eggs

  Place all the dry ingredients, including the yeast, together and mix lightly. Add the oil and eggs and beat all together. Fold in the zucchini and stir thoroughly for at least 2 minutes. Carefully add the blueberries and stir. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  Pumpkin Bread

  2 cups bread flour, sifted 1 teaspoon cinnamon 1 teaspoon nutmeg 2 teaspoons Instant yeast (check the Best Before date on the sachet) 1 teaspoon salt ¼ cup water 1 cup walnuts, coarsely chopped 1 cup white sugar ½ cup olive oil 2 eggs, beaten

750g (1lb 10 oz) butternut pumpkin, cubed

  Fill one black pot-bellied pot two-thirds full with water (about 5-7 cups of water) and add salt. Close the lid and allow to heat in the solar cooker until water is boiling or close to boiling (about 2 hours). At this stage add the pumpkin and cook until tender (about a further 2 hours). Mash the pumpkin, sieve and place in a mixing bowl, allowing the pumpkin to cool. When the pumpkin is cool place all the dry ingredients, including the yeast, together and mix lightly. Add the oil, water and eggs and beat all together. Fold in the pumpkin and nuts and stir thoroughly for at least 2 minutes. Knead until smooth and elastic (about 5-10 min).Turn the dough into a well-greased black pot. Put the lid on the pot and cook for approximately 2 hours.

  Pot Bread

  1kg (2lbs 3 oz) bread flour, sifted 4 tablespoons white sugar 10g (2 teaspoons) Instant yeast (check the Best Before date on the sachet) 4 teaspoons salt 65g (3 oz) butter, soft 2 ¾ cups water

  Mix flour, sugar and salt together. Fold in the butter and mix until the butter looks like breadcrumbs. Uniformly mix in the yeast. Add in water gradually and knead/ stretch the dough for 15 minutes. Cover the dough in plastic and wrap a small, clean towel around the dough. Place this in the sun for 1-2 hours. After 1-2 hours, knock the

dough down to size. Turn the dough into a well-greased black bellied pot. Put the lid on the pot and cook for approximately 3-4 hours.

  2. Solar Soups

  Chicken Asparagus Soup

  700g (1lb 8 oz) deboned, chicken breasts (tenders), cut into cubes (small bit-sized bits) ½ cup chopped onion 2 stalks celery, sliced 340g (12oz) chickpeas, soaked overnight 2 carrots, sliced and diced 2 cups frozen corn kernels (maize) 2 cans cream of mushrooms soup 1 ½ cups chicken broth/ stock 1 teaspoon dried dill weed ½ cup milk/ cream (either or even mixed together) or ½ cup evaporated milk 1 large can of cooked asparagus, drained and cubed

  Initially rinse the chickpeas and then in a black pot-bellied enamel pot add all the ingredients except the ½ cup milk/ cream or ½ cup evaporated milk. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day.

  1 hour prior to completion, add the ½ cup milk/ cream or ½ cup evaporated milk, stir briefly, replace the lid and cook for 1 further hour in the sun. Add salt and pepper where necessary.

 

Bean and Beef Soup

  2 cups of mixed beans of your choice 1 teaspoon crushed garlic ½ cup chopped onion 3 tablespoons dried parsley 1 teaspoon oregano 1 cup chopped tomatoes 1 pepper finely chopped 1 small can mushrooms 1 can cream of mushrooms soup 8 strips of bacon, cut into small bits 300g (10 oz) finely diced beef 2 beef cubes/ stock in 1cup of water (well mixed)

  In a black pot-bellied enamel pot add all the ingredients except the diluted beef stock, mix well. Add the beef stock and stir well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day, without stirring.

  1 hour prior to completion, remove the lid, stir well and replace the lid. Cook for a further hour in the sun. Add salt and pepper where necessary.

  Vegetable Pasta Soup

  1 can mixed vegetable juice 1 cup water 1 large potato, finely diced 1 cup chopped onion, finely diced

2 cups large shell-shaped pasta 1 teaspoon crushed garlic 2 carrots, finely sliced 2 stalks celery, diced 1 can diced tomatoes 1 cup chopped fresh green beans 1 cup fresh corn kernels (maize) 2 cups large shell-shaped pasta 1 cup chicken stock (chicken broth) or alternatively 1 can cream of chicken soup

  In a black pot-bellied enamel pot add all the ingredients and mix well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day, without stirring.

  1 hour prior to completion, remove the lid, stir well and replace the lid. Cook for a further hour in the sun. Add salt and pepper where necessary.

  Tomato Mushroom Soup

  1 can condensed tomato soup 1 can milk equivalent 1 can water equivalent 250g (9 oz) of finely sliced mushrooms/ tortellini 1 cup chopped onion 2 tablespoons red pepper flakes or finely diced red pepper Italian seasoning to taste 1 cup cheddar cheese, grated

 

In a black pot-bellied enamel pot add all the ingredients and mix well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day, without stirring.

  1 hour prior to completion, remove the lid, stir well and replace the lid. Cook for a further hour in the sun. Add salt and pepper where necessary. Serve with some grated cheese sprinkled in.

  Butternut Soup

  1 large butternut (butternut squash) 1 cup milk 1 cup chopped onion, finely diced 1 teaspoon garlic 2 carrots, finely sliced 2 stalks celery, diced fresh sage 4 cups chicken stock (chicken broth) or alternatively 3 cans cream of chicken soup

  In a black pot-bellied enamel pot add all the ingredients and mix well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day, without stirring.

  1 hour prior to completion, remove the lid, stir well and replace the lid. Cook for a further hour in the sun. Add salt and pepper where necessary.

  In general soups are relatively easy to make in a solar cooker and can be experimented with using different ratios of liquids, different size food

particles, either big and chunky or smooth and more like puree.

  In addition some cream, garlic, croutons, rocket or any fragrant vegetables add a potential multiplicity of different tastes and textures to the soups, depending on personal preferences.

  Fish Soup

  4 white fish fillets, deboned (100-150 g fillets/ 4-6 oz fillets) 1 cup dry white wine 1 green pepper, finely diced 1 tomato, finely diced 2 stalks celery, finely chopped 1 cup chopped onion, finely diced 1 teaspoon garlic 2 carrots, finely sliced 2 tablespoons fresh fennel ½ cup milk/ cream

  In a black pot-bellied enamel pot add all the ingredients except the fish fillets and mix well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and commence cooking.

  In a black lidded-rectangular pan place the fish fillets, drizzle with olive oil and a squeeze of lemon juice, close the pan and cook. Once the fillets are cooked, remove, carefully cut into small cubes. Remove the lid from the black pot, add the fish flesh, stir well, taste briefly and add salt, pepper and mixed herbs where necessary and replace the lid. Cook for the rest of the day.

  1 hour prior to completion, add the ½ cup cream, stir briefly, replace the lid and cook for 1 further hour in the sun. Add salt, pepper, herbs and spices where necessary.

  White Onion Soup

  1kg (2lbs 3 oz) onions finely sliced and diced 1 cup dry white wine ½ cup double-thick cream 1 green pepper, finely diced 1 red pepper, finely diced 2 stalks celery, finely chopped 1 teaspoon crushed garlic 2 carrots, finely sliced 2 tablespoons fresh fennel 3 cups chicken stock (chicken broth)

  In a black pot-bellied enamel pot add all the ingredients and mix well. Do not add any additional water. Close the lid tightly, place the pot in the solar cooker before 09h00 and cook all day, without stirring.

  1 hour prior to completion, remove the lid, stir well and replace the lid. Cook for a further hour in the sun. Add salt, pepper, herbs and spices where necessary.

  3. Solar Pasta

  Tuna Macaroni Cheese

  2 cans tuna (drained) 2 cups macaroni pasta 1 cup of grated mozzarella cheese 4 tablespoons flour 2 cups of milk at ambient temperature (do not use cold milk) 4 cups of grated cheddar cheese 1 onion, finely diced 1 cup cherry tomatoes 1 cup of breadcrumbs (slightly toasted) 3 tablespoons of olive oil

  Fill one black pot-bellied pot two-thirds full with water (about 5-6 cups of water) and add salt. Close the lid and allow to heat in the solar cooker until water is boiling or close to boiling. At this stage add the macaroni to the pot. Add a little olive oil and allow to cook until “al dente”, usually about 30-45 minutes. Check after 15 minutes to avoid overcooking the paste.

  In a second black pot-bellied pot add the diced onion and 2 table spoons of olive oil and cook for 1 hr. Remove from the solar cooker and set the cooked onion aside (preferably in the fridge). Clean the pot and then add 2 cups of milk and 4 tablespoons of flour and mix thoroughly using an electric whisk or equivalent.

  Add this pot to the solar cooker and wait for the mix to heat up and start thickening. Once the mixture starts thickening it will require further whisking to avoid lumps forming and to ensure a smooth sauce prior to adding the grated cheese. Stir well and then remove the pot from the solar cooker and add 2 cups of grated cheese to the mix and mix well. Add the cooked onion and cherry tomatoes into this mix.

  Once the macaroni is cooked, remove the first pot and drain the macaroni in a colander or sieve. Toss the macaroni back into the pot and fold in the cheese, flour and milk mixture (cheese sauce). Carefully drain two tins of chunky tuna and using a fork flake the fish into the macaroni and cheese sauce, combining well.

  Add seasoning to taste. Mix well then pour into a greased, flat, blacklidded casserole dish or baking pan. Mix the 2 cups of grated cheddar with the one cup of grated mozzarella cheese and sprinkle this cheese evenly over the top. Over this sprinkle 1 cup of breadcrumbs. Fit the lid and place back in to the solar cooker and cook for at least 90 minutes or longer.

  Spaghetti Bolognaise

  750g (1lbs 10 oz) lean steak mince (ground beef) 300-400g (12 oz) spaghetti 1 large onion, finely diced 1 teaspoon crushed garlic/ 2 garlic cloves, crushed 1 tablespoon olive oil 2 tomatoes, diced 1 cup beef stock (1 cube dissolved in a cup of water)

1 teaspoon oregano 1 teaspoon basil 1 small can of mushrooms (drained) 2 tablespoons parmesan cheese (grated)

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). In a second black bellied pot add the olive oil, mince, mushrooms, diced onion, garlic, diced tomatoes, oregano and basil. Close the lid and allow to cook. Cook the mince mixture for 2 hours. After 2 hours open the lid, stir well, add salt, pepper and mixed herbs to taste, then add the 1 cup of beef stock, close the lid and cook for a further 2-3 hours.

  45 minutes before eating add the spaghetti to the boiling water in the first black pot, add a little olive oil and cook until “al dente”, should take 20-30 minutes. Once the spaghetti is cooked, remove this first pot and drain the spaghetti in a colander or sieve. Toss the spaghetti back into the empty pot and carefully pour the mince mixture from the second pot into the first pot. Mix well and taste one last time. If necessary add salt, pepper and mixed herbs. Top with grated parmesan cheese and serve.

  Spaghetti Bake

  250 g (9 oz) spaghetti 250 g (9 oz) bacon bits 2 onion, sliced 1 green pepper, cored and diced 4 tomatoes, finely diced 5 eggs

2 cups milk 1 teaspoon mustard salt, pepper and mixed herbs to taste 1 teaspoon parsley 3 cups grated cheddar cheese

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). After heating for 2 hours add the spaghetti, add a little olive oil and cook until ‘al dente’. In a second black bellied pot add the olive oil, onion, bacon and tomatoes. Close the lid and allow to cook for 2 hours.

  Once spaghetti is cooked remove and layer in a lidded-solar baking tray. Pour the bacon mix over the top of the spaghetti. Beat the eggs, milk, salt, pepper, mustard, mixed herbs and parsley together and pour over mixture. Sprinkle the cheddar cheese uniformly over the top. Replace the lid and allow to cook for a further 2 hours.

  Fettuccine Alfredo

  450-500g (1lb) cooked ham, sliced and diced into bite-sized bits 500g (1lb 2 oz) fettuccine pasta 250g (9 oz) mushrooms, diced into bite-sized bits 1 large onion, finely diced 1 teaspoon crushed garlic/ 2 garlic cloves, crushed 1 tablespoon olive oil 1 cup cream ½ cup plain yoghurt 1 teaspoon basil

2 tablespoons parmesan cheese (grated)

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). In a second black pot-bellied pot add the olive oil, ham, basil, garlic, onion and mushrooms. Close the lid and allow cooking to commence.

  Cook the ham, mushroom and onion mixture for 2 hours. After 2 hours open the lid, add the yoghurt and cream, stir well. Close the lid and cook for a further 2-3 hours.

  45 minutes before eating add the fettuccine pasta to the hot, steaming water in the first black pot, add a little olive oil and cook until “al dente”, should take 20-40 minutes, depending on the conditions.

  Once the pasta is cooked, remove this first pot and drain the pasta in a colander or sieve. Toss the pasta back into a large serving bowl and carefully pour the mixture from the second pot into this bowl. Mix well and taste. If necessary add salt, pepper and mixed herbs. Sprinkle the parmesan cheese on top and serve.

  Fettuccine Seafood Alfredo

  300g (10 oz) cooked muscle meat, defrosted 750g (1lb 10 oz) prawns (medium size), defrosted, deveined and shelled 500g (1lb 2 oz) fettuccine pasta 250g (9 oz) mushrooms, diced into bite-sized bits 1 large onion, finely diced

1 teaspoon crushed garlic/ 2 garlic cloves, crushed 1 tablespoon olive oil 2 cups cream 1 teaspoon basil 2 tablespoons parmesan cheese (grated)

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). In a second black pot-bellied pot add the olive oil, basil, garlic, onions, mushrooms, prawns and mussel meat. Close the lid and allow to start cooking. Cook this mixture for 2 hours. After 2 hours open the lid, add the 2 cups of cream, stir well. Close the lid and cook for a further 2-3 hours.

  45 minutes before eating add the fettuccine pasta to the steaming water in the first black pot, add a little olive oil and cook until “al dente”, should take 20-30 minutes. Once the pasta is cooked, remove this first pot and drain the pasta in a colander or sieve. Toss the pasta back into the empty pot and carefully pour the seafood and mushroom mixture from the second pot into the first pot. Mix well and taste. If necessary add salt, pepper and mixed herbs. Sprinkle the parmesan on top and serve.

  Chicken Lasagna

  250g (9 oz) lasagna noodles, raw 750-900g (1lb 10 oz) deboned chicken breast, diced into bite-sized bits 1 can condensed cream of chicken soup 1 can condensed cream of mushroom soup 1 large onion, finely diced 1 can mushrooms, drained

1 teaspoon crushed garlic/ 2 garlic cloves, crushed 2 tablespoons olive oil ½ cup parmesan cheese, grated 4 cups Cheddar cheese, grated

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). In a second black pot-bellied pot add the olive oil, diced chicken, garlic and onions. Close the lid and allow to start cooking. Cook the mixture for 2 hours. After 2 hours open the lid, add the mushrooms, chicken soup and mushroom soup, stir well. Close the lid and cook for a further 2 hours. Add salt, pepper or mixed herbs to taste.

  Once the water boils or approaches boiling point in the first pot, add 1 tablespoon of olive oil and immediately thereafter add the lasagna noodles to the hot water and stir. Cook until “al dente”, should take 20-30 minutes, stirring again after 10 minutes (the combination of stirring and olive oil will prevent the noodles from sticking together).

  Once the lasagna noodles are cooked, remove this first pot and drain the noodles carefully in a colander or sieve. In a greased flat black liddedcasserole dish or baking pan, layer half of the noodles on the bottom of the dish. Layer the soup and chicken mixture over this finally ending with a layer of 2 cups of cheese. Repeat this entire sequence again. Sprinkle the parmesan cheese on top of this final layer of cheddar cheese. Fit the lid and place back into the solar cooker and cook for at least 90 minutes or longer.

  4. Solar Cake Baking

  Apart from the specific weather circumstances and type of solar cooker, of importance when baking cakes in a solar cooker is the type of cooking container and the length of cooking. A process of trial and error might be required to find the most suitable cooking container, but essentially a normal round black cooking pot should suffice, or try an 8X8-inch square (or round equivalent) black lidded-cake pan. Avoid opening the solar cooker and breaking the heat seal and resist the temptation to take the cake out too soon.

  Carrot Cake

  4 eggs, large 1½ cups pecan or walnut nuts, coarsely chopped 3 teaspoons vanilla essence (vanilla extract) 2 cups cake flour/ all-purpose flour, sifted ½ teaspoon salt 2 teaspoons baking soda 2 cups white sugar 1 cup canola oil 2 teaspoons ground cinnamon 2 teaspoons baking powder ½ cup butter (must be soft) 3 cups finely grated carrots 250g (9 oz) cream cheese 4 cups icing (confectioners) sugar

2 teaspoons lemon zest (grate the coloured part of a lemon rind to get the zest)

  Grease the cake pan. In a mixing bowl add the flour, baking soda, baking powder, cinnamon and salt. Mix well using a whisk.

  In a separate bowl using an electric mixer add the eggs and beat until frothy on high-speed, usually about 1-2 minutes. Continue to mix but now slowly add in the sugar and mix well, for about 5 minutes. Add the canola oil and 2 teaspoons vanilla extract, mixing well.

  Now add the flour mixture to the egg mixture and mix briefly (do not over-mix). Fold in the grated carrots and 1 cup of nuts. Add to the cake pan, put on the lid and place in a pre-heated solar cooker and cook for between 3-4 hours. The cake is ready when it feels firm and a toothpick inserted in the middle comes out clean. Carefully remove the cake and allow to cool.

  Make the icing (frosting) in another bowl also using an electric mixer. Add the butter and cream cheese and mix on low-speed until smooth. Slowly add the icing sugar and similarly mix on low-speed until smooth. Add the lemon zest and vanilla essence and mix well until mixture is smooth and creamy. Fold in the last of the chopped nuts. Now frost the cooled cake.

  Chocolate Cake

  4 eggs, large 3 teaspoons vanilla essence (vanilla extract)

2 cups cake flour/ all-purpose flour, sifted ½ teaspoon salt 2 teaspoons baking soda 2 cups white sugar 1 cup canola oil 2 cups unsweetened baking cocoa 1 cup water 2 teaspoons baking powder ½ cup butter (must be soft) 4 cups icing (confectioners) sugar 1 cup of milk 1 small peppermint crisp

  Grease 2 black cake tins. In a mixing bowl add the flour, baking soda, baking powder, 1 cup unsweetened baking cocoa and salt. Sift the entire mixture back into a bowl and then sift for a second time back into a bowl (the sifting process effectively aerates the mix and reduces the risk of the cake flopping). Mix well using a whisk.

  In a separate bowl using an electric mixer add the eggs and beat until frothy on high-speed, usually about 1-2 minutes. Continue to mix but now slowly add in the sugar and mix well, for about 5 minutes. Add the canola oil and 2 teaspoons vanilla extract, mixing well.

  Now gradually add the flour mixture to the egg mixture and mix briefly (do not over-mix). Whilst adding in the flour mix, simultaneously add in 1 cup of water. Time it so that the cup of water is added in progressively with the flour mix. Add the final mixture equally to the two cake tins. Place both cake tins in a pre-heated solar cooker and cook for between 2-3

hours. The cake is ready when it feels firm and a toothpick inserted in the middle comes out clean. Carefully remove the cake and allow to cool.

  Make the icing (frosting) in another bowl also using an electric mixer. Add the butter and the other cup of cocoa and mix on low-speed until smooth. Slowly add the icing sugar and similarly mix on low-speed until smooth. Add the vanilla essence, and then gradually add the milk and mix well until the mixture reaches spreading consistency. It might not be necessary to add all the milk. Now frost the cooled cake. Take a small peppermint crisp and crush it into coarse particles. Sprinkle the peppermint crisp particles uniformly on top of the frosting.

  Blueberry Cheese Cake

  4 eggs, large 1 teaspoon vanilla essence (vanilla extract) ½ cup butter (must be soft) 175g (6 oz) digestive biscuits ¾ cup castor sugar 450g (1lb) cream cheese 2 tablespoons icing sugar 250g (9 oz) blueberries

  Grease the cake pan. In a food processor dice the biscuits down to the size of breadcrumbs. Mix the biscuit mash with the butter and using this mix form a crust on the base of the cake pan. Add 80% the blueberries uniformly over this base.

 

In a separate bowl using an electric mixer add the eggs, icing sugar, cream cheese and vanilla extract. Beat until smooth and creamy with no visible lumps (be careful of not overbeating or mixing at too high a speed as cheese cakes are prone to collapsing if over-aerated). Add this mixture on top of the blueberries.

  Place the lidded-cake pan in a pre-heated solar cooker and cook for between 2-3 hours. Do not open too early as this can cause the cheesecake to crack prematurely. The cake is ready when it feels firm and only shakes slightly when you shake the cake pan. Allow the cake to cool for at least 30 minutes, and then remove from the cake pan. Sprinkle the last of the blueberries and the icing sugar over the cake.

  Coconut Cake

  5 eggs, large 3 teaspoons vanilla essence (vanilla extract) 3 teaspoons almond essence (almond extract) 3 cups cake flour/ all-purpose flour, sifted ½ teaspoon salt 2 teaspoons baking soda 2 cups white sugar 2 teaspoons baking powder 1 cup butter (must be soft) 450g (1lb) icing (confectioners) sugar 1 cup of milk 300g (10 oz) sweetened, shredded coconut 450g (1lb) creamed cheese

 

Grease the cake pan. In a bowl using an electric mixer add the butter and sugar and mix on medium speed until a creamy texture is achieved. Add the eggs and mix. Add 2 teaspoons of almond essence and 2 teaspoons of the vanilla essence and mix well.

  In a separate mixing bowl add the flour, baking powder, baking soda and salt. Mix well using a whisk and thereafter gradually add the milk whilst mixing. Now gradually add this mixture to the first bowl and mix well. Fold in 200g (7 ounces) of the shredded coconut.

  Add to the cake pan, put on the lid and place in a pre-heated solar cooker and cook for between 2-3 hours. The cake is ready when it feels firm and a toothpick inserted in the middle comes out clean. Carefully remove the cake and allow to cool.

  Make the icing (frosting) in another bowl also using an electric mixer. Add the butter, cream cheese, 1 teaspoon of almond essence and 1 teaspoon of vanilla extract. Add the icing sugar and mix until smooth with no lumps. Frost the top and sides of the cake and sprinkle the last of the shredded coconut over the top and sides.

  5. Solar Vegetables

  Vegetable Stir Fry

  4 tablespoons olive oil 1 red bell pepper, cored, seeded, and julienned 1 yellow pepper, cored, seeded, and julienned 2 large onions, thinly sliced 2 baby marrows, thinly sliced 1 cup small broccoli florets 1 baby eggplant, cut into chunks 3 medium carrots, peeled and julienned 1 teaspoon crushed garlic or alternatively 1clove garlic, crushed 2 cups mushrooms, thinly sliced salt, pepper and mixed herbs to taste

  Pre-heat the solar cooker. Add all the ingredients into two separate solar black pots and mix well, ensuring vegetables are properly coated with oil.. Close the lids tightly on both pots, place in the cooker and leave to cook unattended for a minimum of 3-4 hours

  Potato Bake

  4 large potatoes, cleaned and thinly sliced 1 cup bacon, finely diced 1 onion, finely diced 2 cups cream

3 cups grated cheddar cheese 1 yellow pepper, cored, seeded, and finely diced 2 cups mushrooms, finely diced ½ cup of milk salt, pepper and mixed herbs to taste

  Pre-heat the solar cooker. Spread a layer of potatoes on the bottom of a solar pan (approximately 15x10x2 inches). On top of that sprinkle a generous layer of mixed bacon, pepper, mushrooms, onion, cream and a handful of cheese. On top of that place another layer of thin sliced potatoes. Continue to layer the dish until the pan is full. Ensure the final layer is a thick layer of cheese. Pour the milk lightly over the top. Close the lid and place the pan in the solar cooker. Cook for 3-4 hours.

  Broccoli Bake

  1.5kg (3lbs 5 oz) broccoli, chopped 3 cups rice ½ cup celery, finely chopped 1 yellow pepper, cored, seeded, and finely diced 2 cups mushrooms, finely diced 1 can cooked asparagus, drained 1 can cream of mushroom soup 1 onion, finely diced 2 cups grated cheddar cheese salt, pepper and mixed herbs to taste

  Initially cook the broccoli separately. Add broccoli to a black solar pot with ½ cup of water. Close the lid and cook for 2 hours. After 2 hours remove the broccoli. In another black solar pot add the rice, onion, celery,

asparagus, broccoli, mushrooms, pepper and can of cream of mushroom soup. On top add the grated cheese. Close the lid and cook for a minimum of 4 hours.

  Vegetarian Lasagna

  250g (9 oz) lasagna noodles, raw 250g (9 oz) broccoli, chopped 250g (9 oz) spinach, finely chopped 250g (9 oz) cottage cheese 2 cans condensed cream of mushroom soup 1 large onion, finely diced 1 can cooked asparagus, drained 2 eggs 2 cans mushrooms, drained 1 teaspoon crushed garlic/ 2 garlic cloves, crushed 1 tablespoon olive oil ½ cup parmesan cheese, grated 5 cups Cheddar cheese, grated

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). In a second black bellied pot add the olive oil, I can mushroom soup, broccoli, spinach, garlic and onion.

  Close the lid and allow to start cooking. Cook the mixture for 2 hours. After 2 hours open the lid, add the mushrooms, asparagus and mushroom soup, stir well. Close the lid and cook for a further 2-3 hours. Add salt, pepper or mixed herbs to taste.

  Once the water boils in the first pot, add a little olive oil and add the lasagna noodles to the boiling water and cook until “al dente”, stirring after 10 minutes to prevent the noodles from clumping together. This should take 20-30 minutes. Once the lasagna noodles are cooked, remove this first pot and drain the noodles carefully in a colander or sieve.

  In a greased flat black lidded-casserole dish or baking pan, layer half of the noodles, vegetable mixture, and cheese. Mix the cottage cheese, ¼ cup parmesan cheese and egg and layer this over the vegetable mix.

  On top of this place the rest of the noodles. Apply the remaining vegetable mix over this. Add the balance of the cheddar cheese and sprinkle the last of the parmesan cheese on top of this final layer of cheddar cheese. Fit the lid and place back in to the solar cooker and cook for at least 90 minutes or longer.

  Creamed Green Beans

  1 teaspoon crushed garlic or alternatively 2 cloves garlic, crushed 2 cans of cut beans ½ cup celery, finely chopped 3 tablespoons olive oil 3 cups mushrooms, finely diced 1 can cooked asparagus, drained 1 can cream of mushroom soup 1 onion, finely diced 2 cups grated cheddar cheese 1cup pecan or walnut nuts, coarsely chopped

salt, pepper and mixed herbs to taste

  In a black pot-bellied pot add the olive oil, celery, garlic, mushrooms and onions. Close the lid and allow to cook. Cook the mixture for 2 hours. After 2 hours add in the soup, asparagus and nuts and allow to cook for a further hour.

  Taste and add salt, pepper or mixed herbs if required. Then stir in the beans carefully, add the mixture to a lidded-solar baking dish. Sprinkle the cheddar cheese uniformly on top, place the lid on tightly and cook for another 1 hour.

  Pumpkin Pie

  85g (3 oz) butter, cubed 2 teaspoons castor sugar 1teaspoon ground cinnamon 2 eggs lightly beaten 1 cup brown sugar ½ cup cream 2 tablespoons sherry 1 teaspoon nutmeg 1 teaspoon ginger 4 tablespoons cold water 750g (1lb 10 oz) butternut pumpkin, cubed 1½ cups all-purpose flour, sifted

  Fill one black pot-bellied pot two-thirds full with water (about 5-6 cups of water) and add salt. Close the lid and allow to heat in the solar cooker

until water is boiling or close to boiling (about 2 hours).

  At this stage add the pumpkin and cook until tender (about a further 2 hours). Mash the pumpkin, sieve and place in a mixing bowl, allowing the pumpkin to cool.

  30 minutes before the pumpkin is finished cooking add the flour to a mixing bowl and fold in the butter and mix until the butter looks like breadcrumbs. Add the castor sugar and mix.

  Thereafter make a hole in the centre at the bottom and add the water. Slowly mix the dried ingredients in with the water using a table knife until mixing is complete. Knead the mixture until firm, remove, cover and refrigerate this pastry mix for 30 minutes.

  After 30 minutes remove and line the base and sides of a lidded-solar baking dish. Crimp the edges with a fork and discard the excess pastry.

  In a separate mixing bowl mix the eggs and sugar well. Now add the cooled pumpkin, sherry, cinnamon, nutmeg, ginger and cream. Mix well and then add the mixture into the lidded-solar baking dish.

  Smooth the surface using the blade of a table knife. Close the lid and place the dish in the solar cooker and cook for a further 2-3 hours. Allow to cool and refrigerate.

  6. Solar Desserts

  Rice Pudding

  1 cup uncooked white rice 2 cups milk ½ cup white sugar ½ teaspoon salt ½ teaspoon cinnamon 1 egg, beaten 1 cup golden raisins 1 tablespoon butter, soft ½ teaspoon vanilla essence (extract)

  Fill one black pot-bellied pot two-thirds full with water (about 5-6 cups of water) and add salt. Close the lid and allow to heat in the solar cooker until water is boiling or close to boiling (about 2 hours). At this stage add the rice and allow to cook to completion, (about 2 hours). Remove and sieve the rice.

  In another black pot-bellied pot add the cooked rice, 1½ cups milk, cinnamon, sugar and salt. Stir well, close the lid and cook for 2 hours minimum, until thick and creamy. Add the last of the milk, the egg and raisins, stir well and cook for a further 1 hour. Add the vanilla and butter and stir well.

  Apple Danish

  3 cups all-purpose flour ½ cup milk 2 cups white sugar ½ teaspoon salt 1 teaspoon ground cinnamon 1 egg yolk 1 egg white, beaten 1½ cup butter, soft 6 cups apples, peeled and finely diced ½ teaspoon vanilla essence (extract)

  Add the flour and salt to a mixing bowl and fold 1 cup of the butter and mix until the butter looks like breadcrumbs. Add the egg yolk and milk and mix. Divide the pastry in half and with one half line the base and sides of a lidded-solar baking dish. Crimp the edges with a fork. Set aside the other half of the pastry.

  In a separate mixing bowl add the sugar, cinnamon, apples and the rest of the butter. Mix well. Spoon into the baking dish on top of the pastry. Spread out evenly and spread out the other half of the pastry on top of the mix, sealing the dish off. Brush thoroughly with the egg white. Put on the lid of the solar baking dish, place in the solar cooker and cook for a minimum of 3-4 hours.

  Milk Tart

  1 cup cake flour, sifted 4 cups milk

1 cup white sugar ½ teaspoon salt 1 tablespoon ground cinnamon 3 egg yolks 3 egg whites, beaten 1½ cup butter, soft 1 teaspoon baking powder 1 teaspoon vanilla essence (extract)

  Add the butter and sugar in a mixing bowl and mix until smooth with no lumps. Add the egg yolks and beat until light and fluffy. Add the salt, baking powder and cake flour and mix well. Add the milk and vanilla essence and mix well.

  In a separate mixing bowl add the egg whites and blend thoroughly on high-speed with an electric blender until the mixture is fairly stiff. Add this to the first mixing bowl and mix thoroughly. Pour the mix into a greased solar baking dish and sprinkle the cinnamon uniformly on top of the mix. Put on the lid of the solar baking dish, place in the solar cooker and cook for a minimum of 3-4 hours.

  Banana Toffee Pie

  300g (10 oz) butter, soft 250g (9 oz) digestive biscuits 1 can condensed milk 1 cup cream 90g (3 oz) castor sugar 5 bananas, thinly sliced 2 small peppermint crisps, finely crushed

  In one black pot-bellied pot mix 150g (5 oz) butter and the castor sugar. Replace the lid and melt the mixture (about 1 hour). Once the sugar has melted completely, add the tin of condensed milk to the pot, stir well, replace the lid and allow to heat up. After 1 hour open the pot, add the bananas, stir well and replace the lid. Cook the caramel mixture for a further 3 hours, stirring every hour. Thereafter remove the caramel and banana mixture from the solar cooker and allow to cool to ambient temperature.

  30 minutes prior to the caramel and banana mixture being ready add 150g (5 oz) butter to a second black bellied pot, close the lid and melt in the solar cooker. Meanwhile crush the digestive biscuits into fine crumbs in a mixing bowl. Once the butter is melted, add the crushed digestive biscuits on top of the butter and mix well. Take this mixture and carefully line the inside of a cake/ pie tin (leaving no gaps) and refrigerate the tin for 30 minutes.

  Add the cream to a mixing bowl and beat on a high-speed using an electric beater until the cream is stiff. Remove the cake/ pie dish from the fridge, uniformly spoon the caramel and banana mix into the dish. Uniformly layer the cream over the top and then sprinkle the crushed peppermint crisps over that. Refrigerate for 2 hours prior to serving.

  Apple Marshmallow Toffee Pie

  300g (10 oz) butter, soft 250g (9 oz) digestive biscuits 1 can condensed milk

1 cup cream 90g (3 oz) castor sugar 5 apples, peeled, cored and diced into small, bite-sized bits 2 cups of marshmallows, finely diced 2 teaspoons ground cinnamon

  In a black pot-bellied pot add the diced apples, marshmallows, 1 teaspoon cinnamon, vanilla essence and sugar. Mix well. Replace the lid and cook in the solar cooker for 2 hours.

  In a second black pot-bellied pot mix 150g butter (5 oz) and the castor sugar. Replace the lid and melt the mixture (about 1 hour). Once the sugar has melted completely, add the tin of condensed milk to the pot, stir well, replace the lid and allow to heat up.

  After 2 hours open the pot, add the mix from the other pot, stir well and replace the lid. Cook the caramel/ marshmallow mixture for a further 3 hours, stirring every hour. Thereafter remove the caramel/ marshmallow mixture from the solar cooker and allow to cool to ambient temperature.

  30 minutes prior to the caramel/ apple and marshmallow mixture being ready add 150g butter (5 oz) to a black pot-bellied pot, close the lid and melt in the solar cooker.

  Meanwhile crush the digestive biscuits into fine crumbs in a mixing bowl. Once the butter is melted, add the crushed digestive biscuits on top of the butter and mix well. Take this mixture and carefully line the inside of a cake/ pie tin (leaving no gaps) and refrigerate the tin for 30 minutes.

 

Add the cream to a mixing bowl and beat on a high-speed using an electric beater until the cream is stiff.

  Remove the cake/ pie dish from the fridge, uniformly spoon the caramel/ marshmallow mix into the dish. Uniformly layer the cream over the top and then sprinkle 1 teaspoon of cinnamon on top. Refrigerate for 2 hours prior to serving.

  Apple Crumble

  1 cup all-purpose flour, sifted 5 teaspoons white sugar 1 teaspoon ground cinnamon 90g (3 oz) butter, soft 90g (3 oz) brown sugar ½ cup raisins 1 can unsweetened pie apples

  Add the flour, brown sugar and fold in the butter and mix until the butter looks like breadcrumbs.

  In a separate mixing bowl add the apples, white sugar, cinnamon and raisins. Mix well. Uniformly spoon this mixture to a greased solar baking dish. Sprinkle the butter mix uniformly over the top. Replace the lid of the solar pan and cook in the solar oven for a minimum of 3 hours.

  7. Solar Chicken

  Chicken and Prawn Curry with Samp

  1 cup samp (dried corn soaked overnight 8 pieces chicken thighs 2 punnets mushrooms 300g (10 oz) prawns, deveined, thawed and shelled 1 onion, sliced 1 can whole, peeled tomatoes, drained and finely diced 2 tablespoon brown sugar 2 teaspoons coriander 2 teaspoons cumin seed 1 tablespoon olive oil 1 tablespoon ginger, grated 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 cubes chicken stock 5 teaspoons hot curry powder 1 packet curry paste mix 1 cup water at ambient temperature (do not use cold water)

  Soak the samp in water overnight (ensure the samp is fully covered by the water. The samp will expand during the course of the evening). The following morning drain the samp and then add the samp plus 1 cup of tap water into one black bellied pot (do not add more than 1 cup of water). Allow to cook for at least 3-4 hours.

 

Heat an empty second black pot for 30 minutes and then combine the olive oil, chicken pieces, garlic, onions and mushrooms. Cook for 2 hours. After 2 hours add chicken stock, tomatoes, coriander, cumin seed, brown sugar, ginger, curry powder and curry paste and 1 cup of tap water (similarly do not add more than 1 cup of water).Allow to cook all day and add the prawns to the curry pot at lunchtime.

  Chicken Casserole (Margaret’s recipe)

  8 pieces chicken pieces 2 punnets mushrooms (250g/ 9 oz each), washed 1 cup of brown rice 1 cup of water at ambient temperature (do not use cold water) 2 cubes chicken stock 1 tin condensed Cream of Mushroom soup 2 cups grated cheddar cheese 1 pinch of paprika 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 onion, diced

  Place the chicken pieces on top of 1 cup of brown rice in a black bellied pot. Pour a tin of condensed Cream of Mushroom soup over the chicken pieces (and rice beneath the chicken).

  Add a full cup of water (not more than 1 cup) to the empty tin and add 2 cubes of chicken stock. Mix well (to ensure the stock is dissolved), and then pour this over the chicken pieces, swishing out the tin to remove any residual soup. Layer on top the 2 containers of mushrooms. Add the paprika, onion and garlic. Add the 2 cups of grated cheddar. Cover and cook in the solar cooker for a minimum of 3-4 hours.

  Chicken A La King

  1 onion finely, chopped 250g (9 oz) mushrooms, sliced into bit-sized bits 1 pinch of paprika 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 chicken stock cube mixed with ½ cup of water (use hot water from the other pot to dissolve the stock) 600g (1lb 5 oz) chicken breasts, deboned and cubed into bit-sized bits 1 cup of cream 1 red pepper, finely chopped 1 yellow pepper, finely chopped 2 tablespoons sherry 3 tablespoons olive oil Salt, pepper and mixed herbs to taste 2 cups of rice 3 cups of water at ambient temperature (do not use cold water)

  Heat an empty black pot for 30 minutes and then combine the olive oil, onions, chicken pieces, peppers, garlic, and mushrooms. Cook for 2 hours. After 2 hours remove the lid, mix well and add the paprika, cream, chicken stock and sherry. Allow to cook for a minimum of 3-4 hours.

  In a second black bellied pot add 3 cups of water, replace the lid and allow to heat in the solar cooker for 3 hours. After 3 hours, add 1 ½ cups of rice to the steaming, hot water and cook until tender (start checking after 30 minutes).

 

Chicken and Leek Pie

  250g (9 oz) mushrooms, sliced into bite-sized bits 1 pinch of paprika 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 chicken stock cube mixed with 1 cup of water 600g (1lb 5 oz) chicken breasts, deboned and cubed into bite-sized bits 1 cup of cream 1 red pepper, finely chopped 1 yellow pepper, finely chopped 60g (2oz) butter 2 tablespoons olive oil salt, pepper and mixed herbs to taste 1 leek, finely sliced 2 tablespoons thyme, finely chopped 2 tablespoons parsley, finely chopped 2 packets puff pastry (250g/ 9 oz each) 1 egg, beaten ½ cup white wine 1 onion, finely sliced

  Heat an empty black pot for 30 minutes and then combine the olive oil, onions, chicken pieces, leek, peppers, garlic, and mushrooms. Cook for 2 hours. After 2 hours add the paprika, cream, chicken stock, thyme, parsley and wine. Allow to cook for a minimum of 2-3 hours.

  Line a shallow lidded-solar baking pan with puff pastry ensuring there are no gaps. Pour the chicken pie mixture into the pan, spreading it uniformly. Spread the puff pastry over the top ensuring the dish is completely sealed. Ensure all the edges are sealed with a fork. Very carefully make a couple

of steam holes in the pastry. Brush uniformly with the beaten egg. Place the lid on top of the solar baking dish and place back into the solar cooker. Cook for the rest of the day.

  Creamy Chicken with Rosemary and Mustard

  1 onion, finely chopped 2 tablespoons wholegrain mustard 2 teaspoons rosemary, finely chopped 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 chicken stock cube mixed with 1 cup of water 8-12 chicken pieces (depending on the size of your pots) 1 cup of cream 1 cup dry white wine 1 yellow pepper, finely chopped 60g (2 oz) butter, soft 2 teaspoons olive oil salt, pepper and mixed herbs to taste 3 cups water at ambient temperature (do not use cold water) 1½ cups of rice

  Put the chicken pieces in a ceramic dish. Mix 2 tablespoons of mustard with 2 teaspoons of rosemary and rub this mixture carefully all over the chicken pieces. Refrigerate the chicken pieces overnight.

  Heat an empty black pot-bellied pot for 30 minutes and then combine the olive oil, onion, chicken pieces, butter, pepper and garlic. Cook for 2 hours. After 2 hours add the cream, chicken stock and white wine. Allow to cook for a minimum of 3-4 hours.

  In a second black pot-bellied pot add 3 cups of water, replace the lid and allow to heat in the solar cooker for 3 hours. After 3 hours, add 1 ½ cups of rice to the steaming, hot water and cook until tender (start checking after 30 minutes).

  Roast Chicken with mashed potatoes and corn

  2 onions, whole, peeled 1 whole chicken (giblets removed) 1-1.5kg (2lbs-3lbs) 8 potatoes, peeled and quartered 3 cups of frozen corn 1 cup of cream 60g (2 oz) butter, soft 1 cup milk 2 tablespoons olive oil 1 tablespoon concentrated lemon juice

  Baste the entire outside of the chicken with olive oil. Insert the tablespoon of lemon juice and one onion into the cavity of the chicken. Position the chicken in a solar baking pan with a stainless platform and place the pan in the solar cooker and cook for 3-4 hours.

  In a black pot-bellied solar pot add 5 cups of water at ambient temperature (do not use cold water). Replace the lid and place in the solar cooker. Heat the water until the water is steaming hot (1-2 hours). Carefully remove the lid and add the potatoes cubes. Cook the potato cubes until soft. (time the potatoes to coincide with the chicken being ready to serve).

 

In a second black pot-bellied solar pot add ½ cup of water and similarly allow to heat until the water is steaming. Carefully remove the lid and add the frozen corn and cook until corn is cooked through. Remove the pot and drain the water.

  Remove the pot with the potatoes, drain all the water leaving the potatoes in the pot. Add the cream, 2 tablespoons of butter and salt, pepper and herbs to taste. Cut the remaining onion in half and finely scrap in the inside of the onion (both halves) into the mix. Mash using a utensil or alternatively an electric beater. Mix until smooth and creamy with no lumps.

  Lemon Chicken Casserole

  Ingredients:

  1 onion, finely chopped 250g (9 oz) mushrooms, cleaned and sliced ½ cup sundried tomatoes, sliced 2 tablespoons lemon rind zest (grate the outside of a clean lemon to capture the zest) 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 chicken stock cube mixed with 1 cup of water 8-12 chicken pieces (depending on the size of your pots) 1 cup of cream 1 cup dry white wine 3 lemons, quartered 60g (2 oz) butter, soft 2 teaspoons olive oil salt, pepper and mixed herbs to taste

5 potatoes, peeled, washed and quartered

  Heat an empty black pot for 30 minutes and then combine the olive oil, onion, lemon zest, chicken pieces, butter, salt, pepper and herbs, mushrooms, quartered lemons, quartered potatoes and garlic. Cook for 2 hours. After 2 hours add the cream, chicken stock and white wine. Allow to cook for a minimum of 3-4 hours.

  8. Solar Meat

  Liz Perry’s African Stew

  500g brisket, blade or chuck meat, cubed into bite-sized bits 90-100g (3 oz) sugar beans (soaked overnight) 125g samp (4 oz), soaked overnight 1 onion, chopped 1 teaspoon salt 1 tablespoon olive oil 1 tablespoon butter 1 pinch of pepper 2 tomatoes, chopped 1 green pepper (seeded and chopped) 2 teaspoons lemon juice 1 cup roasted peanuts (unsalted and chopped)

  Remove the sugar beans and samp from water and add these to one black pot. Add fresh water just to cover. Cook for 3 hours.

  Heat an empty second black pot for 30 minutes. Remove the lid, add a tablespoon of butter and a tablespoon of olive oil and add the meat and onion. Brown the meat and onion. Stir in the salt, pepper, tomatoes and green pepper and add fresh water just to cover. Replace the lid and cook in the solar cooker for 2 hours.

 

Thereafter add the beans and samp from the first pot and the lemon juice, to the second pot. Stir in the peanuts, heat the combination for at least another 1 hour and serve.

  Mutton Stew

  1 kg (2.2 lbs) mutton, “best-end”(cubed into small bite-sized chunks) 2 onions, thinly sliced (not chopped) 4 medium potatoes, peeled and diced (rather too small than too big) 2 large carrots, peeled and sliced into rings 1 cup water, ambient temperature 2 cubes beef stock mixed in 1 cup of water 2 tomatoes, coarsely chopped 2 teaspoons salt 1 can beans 1 cup frozen peas 1 cup frozen corn/ maize 1 teaspoon ground cinnamon

  Add the 2 cubes of beef stock and one cup of water to one black bellied pot. To the same black pot add the meat, onions and salt. Cook for 2 hours in the solar cooker. In another black bellied pot add 1 cup of water and the potatoes.

  Cook for 2-3 hours, then open the first black pot, transfer half the meat into the second pot and similarly spread the potatoes evenly between the two pots. Then and add the carrots, tomatoes, beans, peas, corn and spices evenly between the two pots. Cook for a minimum of an additional 3 hours.

  Lamb Chops

  4-6 lamb chops 2 onions, thinly sliced 1 teaspoon paprika 1 tablespoon butter, soft 1 can cream of mushroom soup 250g (9 grams) mushrooms, diced into bite-sized bits 2 teaspoons rosemary, finely chopped 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 yellow pepper, finely chopped 1 red pepper, finely chopped 1 cup celery, finely chopped 3 tablespoons olive oil

  Mix the onions, olive oil, butter, paprika, mushrooms, rosemary, garlic, celery and peppers. Divide this mixture into two equal halves. Spoon the one half uniformly into an empty black bellied pot that has been preheated for 30 minutes in a solar cooker.

  Place the lamb chops on top of this layer. Spoon the other half of the mixture uniformly on top of the chops. Replace the lid and cook in a solar cooker for 3 hours.

  After 3 hours remove the lid, add the cream of mushroom soup, replace the lid and cook for a further 2 hours. Add salt, pepper or mixed herbs to taste.

 

Spaghetti and Meatballs

  ½ cup dry breadcrumbs ¼ cup water ¼ cup parmesan cheese, grated 1 onion, finely chopped 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 2 teaspoons basil 500g (1lb 2 ounces) ground beef (or alternatively lean ground turkey) ½ cup fresh parsley 2 eggs, lightly beaten 1 can tomato/ onion mix

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water).

  In a mixing bowl add the ground beef, eggs, breadcrumbs, water, onion, garlic, parsley, basil and parmesan cheese. Mix ingredients thoroughly. Now shape the mixture into meatballs (1½ - 2 inch diameter).

  Position the individual meatballs in a solar baking tray. Open and pour the tin of tomato and onion mix over the meatballs. Replace the lid on the tray and cook for a minimum of 2 hours.

  40 minutes before eating add the spaghetti pasta to the hot, steaming water in the first black pot, add a little olive oil and cook until “al dente”, should take 20-40 minutes, depending on the conditions. Once the pasta is cooked, remove this first pot and drain the pasta in a colander or sieve.

  Beef Coconut Curry

  60g (2 oz) butter, soft 250g (9 ounces) natural yogurt 2 tablespoons olive oil 2 onions, finely sliced 2 teaspoons ginger, grated 1 teaspoon turmeric 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 2 teaspoons basil 4 tablespoons hot curry powder 2 teaspoons ground coriander 1 teaspoon cumin 2 teaspoons paprika 800g (1lb 12 oz) lean stewing beef or rump steak, fat trimmed, cubed 400ml can coconut milk 4-5 curry leaves 3 cups water at ambient temperature (do not use cold water) 1½ cups of rice

  Mix the cubed meat into the yogurt and add the curry powder. Mix. Allow to marinade for 3 hours in a refrigerator.

  Heat a black pot-bellied pot for 30 minutes and then combine the olive oil, butter, onions, marinated cubed meat, garlic, ginger, turmeric, basil, coriander, paprika and cumin. Cook for 2 hours, stirring after the first hour. After 2 hours add the coconut milk and curry leaves. Allow to cook for a minimum of 3-4 hours.

  In a second black pot-bellied pot add 3 cups of water, replace the lid and allow to heat in the solar cooker for 2 hours. After 2 hours, add 1 ½ cups of rice to the steaming, hot water and cook until tender (start checking after 30 minutes).

  9. Solar Seafood

  Fresh Fish Fillets

  4 fresh fish fillets (any fish with a white, firm fillet of about 200g/ 7 oz each) 1 sliced onion 2 tablespoons butter 2 tablespoons concentrated lemon juice 4 tablespoons olive oil 1 teaspoon parsley pinch of salt and pepper 1½ cups rice 3 cup of water 1 teaspoon turmeric 1 finely diced onion 1 finely diced tomato 1 can sliced mushrooms, drained 1 finely diced green pepper

  In one black pot-bellied pot add 2 tablespoons olive oil, diced onion, diced tomato, diced green pepper and the sliced mushrooms. Allow to cook for approximately 2 hours, stirring after the first hour.

  In anther black pot-bellied pot add the butter, lemon juice, rest of the olive oil, parsley, salt and pepper. Allow to cook to a simmer, ensuring all the butter is properly melted, and the ingredients are properly mixed into a basting sauce. Remove and decant.

  Add the 4 fish fillets (skin down) into a solar baking pan, pour the basting sauce over the fillets, add one sliced onion on top of the fillets, add a film of food grade wax paper on top of the fillets (to reduce any drying out effect), close the lid and cook for between 45 minutes to 90 minutes, depending on the conditions. Start checking the fish after 45 minutes.

  In a third black pot-bellied pot add 3 cups of water, replace the lid and allow to heat in the solar cooker for 2 hours. After 2 hours, add 1 ½ cups of rice and 1 teaspoon turmeric to the steaming, hot water and cook until tender (start checking after 30 minutes). Add salt, pepper and mixed herbs to taste. Drain the rice in a colander. Mix the onions, tomatoes, mushrooms and peppers thoroughly into the rice and serve with the fish.

  Seafood Casserole

  4 fresh fish fillets, cubed into bite-sized bits (any fish with a white, firm fillet of about 200g/ 9 oz each, skinless and deboned) 250g (9 oz) cooked mussel meat 250g (9 oz) prawns, defrosted, deveined and shelled 250g (9 oz) crab sticks, cooked and cubed 2 cups cream ½ cup dry white wine 1 sliced onion 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 2 tablespoons butter 2 tablespoons concentrated lemon juice 4 tablespoons olive oil 1 teaspoon parsley

pinch of salt and pepper 1½ cups rice 3 cup of water 1 teaspoon turmeric 1 finely diced onion 1 finely diced tomato 1 can sliced mushrooms, drained 1 finely diced green pepper

  In one black pot-bellied pot add 2 tablespoons olive oil, diced onion, diced tomato, diced green pepper and the sliced mushrooms. Allow to cook for approximately 1 hour, stirring after the first 30 minutes. Remove and allow to cool.

  In the other black pot-bellied pot pre-heated in a solar cooker for 30 minutes, add the butter, lemon juice, rest of the olive oil, parsley, salt, white wine, garlic and pepper. Allow to cook to a simmer, ensuring all the butter is properly melted, and the ingredients are properly mixed into a basting sauce. Remove and decant.

  Add the fish, mussel meat, prawns and crabsticks into a black bellied pot, pour the basting sauce over the seafood and cook for 1 hour, stirring after 30 minutes. After an hour open the pot and add 2 cups of cream and fish herbs and spices to taste. Add salt and pepper to taste. Close the lid and cook for between 1-2 hours.

  In another black pot-bellied pot add 3 cups of water, replace the lid and allow to heat in the solar cooker for 2 hours. After 2 hours, add 1 ½ cups of rice and 1 teaspoon turmeric to the steaming, hot water and cook until tender (start checking after 30 minutes).

  Add salt, pepper and mixed herbs to taste. Drain the rice in a colander. Mix the onions, tomatoes, mushrooms and peppers thoroughly into the rice and serve with the casserole. On serving, spoon out the rise, and then spoon the seafood casserole on top of the rice, serving with a wedge of lemon.

  Prawn and Pasta Salad

  500g (1lb 2 oz) paste shells 1 onion, thinly sliced 1 onion, finely diced 2 tablespoons mixed nuts, coarsely chopped 2 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 2 tablespoons dry white wine 2 tablespoons lemon juice 5 tablespoons olive oil 1 tablespoon fresh parsley, chopped 1 tablespoon fresh basil, chopped 500g prawns, peeled, deveined and defrosted 1 teaspoon sugar 2 tablespoons butter, soft 1 tablespoon parmesan cheese, grated 150g (5 oz) cherry tomatoes, sliced in halves 1 finely diced green pepper 1 teaspoon turmeric 1 finely diced onion 1 finely diced tomato 1 can sliced mushrooms, drained 1 finely diced green pepper

  In one black pot-bellied pot add 5-6 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water).

  In a second black pot-bellied pot that has been pre-heated for 30 minutes in a solar cooker add 2 tablespoons olive oil, butter, diced onion, garlic, lemon juice and prawns. Allow to cook for approximately 2 hours, stirring after the first hour.

  40 minutes before eating add the pasta and a touch of olive oil to the hot, steaming water in the first black pot and cook until “al dente”, should take 20-40 minutes, depending on the conditions. Once the pasta is cooked, remove this first pot and drain the pasta in a colander or sieve and allow to cool after briefly rinsing in cold water. In a mixing bowl add 3 tablespoons of olive oil, white wine, nuts, basil, parsley, 1 teaspoon garlic, parmesan cheese and sugar. Blend in a food blender until mixture is smooth with no lumps. In a serving bowl add the pasta, tomatoes, sliced onions, green pepper and prawns. Pour the dressing over the salad, toss and garnish with basil leaves.

  Prawn and Coconut Curry

  1 cube chicken stock, fragmented into small pieces 500g (1lb 2 oz) mussel meat, thawed or fresh 500g -1kg (1-2 lbs) prawns, peeled, deveined, thawed or fresh 1 tablespoon ground coriander or alternatively 3 tablespoons coriander stems, chopped 1 can coconut milk

3 onion, finely chopped 4 tablespoons curry powder 1 cup nuts (mixed nuts or according to preference), coarsely ground 2 teaspoons garlic, crushed or alternatively 2 cloves of garlic, crushed 4 tablespoons butter 2 tablespoons concentrated lemon juice 2 tablespoons olive oil 1 teaspoon parsley pinch of salt and pepper 1½ cups rice 3 cup of water 1 teaspoon turmeric 1 finely diced tomato 1 can sliced mushrooms, drained 1 finely diced green pepper

  For this recipe you need 3 black cooking pots and you need to prepare all three pots either simultaneously or in close sequence.

  In one black pot-bellied pot that has been pre-heated for 30 minutes in a solar cooker add 2 tablespoons olive oil, 2 tablespoons butter, 1 diced onion, 1 teaspoon garlic, 2 tablespoons lemon juice, muscle meat and prawns. Allow to cook for approximately 2-3 hours (no stirring).

  Add the coconut milk, chicken stock cube, parsley, 1 diced onion, nuts, 1 teaspoon garlic, curry powder and coriander. Mix well in a food blender. Add to the prawn/ mussel mixture. Cook for a further 3 hours.

  In another black pot-bellied pot that has similarly been pre-heated for 30 minutes in a solar cooker, add 2 tablespoons olive oil, 2 tablespoons

butter, 1 diced onion, 1 diced tomato, 1 diced green pepper and the sliced, diced mushrooms. Allow to cook for a minimum of 3 hours, after which you will add the rice back into this mixture and continue cooking.

  In a third pre-heated black pot-bellied pot add 3 cups of water at ambient temperature, close the lid tightly and place in the pre-heated solar cooker to heat up (do not use cold water). Heat for 2 hours, add 1 ½ cups of rice and 1 teaspoon turmeric to the steaming, hot water and cook until almost tender (start checking after 1 hour, be careful to not overcook).

  Once the rice is cooked, add salt, pepper and mixed herbs to taste. Drain the rice in a colander. Open the pot with the mushroom, green pepper, onion and tomato mixture and add the rice into the pot, mixing well. Close the pot and allow the mixture to continue to cook until the prawn/ mussel curry is complete and ready to serve. When serving, spoon out the rice, and then spoon the seafood casserole on top of the rice, serving with a wedge of lemon.

  Tuna Soufflé

  2 cans tuna (shredded or whole meat with the tuna finely diced, drained) 2 cups milk 5 eggs 2 tablespoons olive oil 2 cups breadcrumbs 1 teaspoon garlic, crushed or alternatively 2 cloves of garlic, crushed 1 tablespoon coriander 1 tablespoon parsley pinch of salt and pepper 1 finely diced onion

1 finely diced green pepper 2 cups grated cheddar cheese.

  In one pre-heated black pot-bellied pot add 2 tablespoons olive oil, diced onion, diced green pepper and garlic. Allow to cook for approximately 1 hour.

  Separate the egg whites and egg yolks. In a mixing bowl add the egg yolks, milk, breadcrumbs, parsley, coriander and tuna. Mix well and then add into the black bellied pot containing the onion mixture. Mix well again. Beat the eggs white until stiff and then fold into the black pot. Now decant the complete mixture from the black pot into a solar pan. Sprinkle the grated cheese uniformly on top. Fit the lid and bake in the solar cooker for 2-3 hours.