Solar Cooking
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Last edited: 28 December 2020      
CooKit photo reversed

CooKits can be purchased from Solar Cookers International inside the United States

PEP cooker tested label 2, 1-13-21

The CooKit was PEP tested with a double Pyrex bowl glazing enclosure.


Panel-style solar cookers are the first solar cookers that are truly affordable to the world’s neediest. In 1994, a volunteer group of engineers and solar cooks associated with Solar Cookers International developed and produced the CooKit, based on a design by French scientist Roger Bernard. Elegant and deceptively simple looking, it is an affordable, effective, and convenient solar cooker. With a few hours of sunshine, the CooKit makes tasty meals for five to six people at gentle temperatures, cooking food and preserving nutrients without burning or drying out. Larger families use two or more cookers (See: Cooking for large groups).

The CooKit is made of cardboard and foil shaped to reflect maximum sunlight onto a black cooking pot that converts sunlight into thermal (heat) energy. A heat-resistant bag (or similar transparent cover) surrounds the pot, acting like a greenhouse by allowing sunlight to hit the pot and preventing heat from escaping. It weighs half a 0.5 kg (1.1 lbs) and folds to the size of a large book for easy transport.

CooKit folded

The CooKit folds to be about the size of a large notebook when not in use.

CooKits are now produced independently in dozens of countries from a wide variety of materials at a cost of USD 3.00 - 7.00.

CooKits complement other cooking methods needed at night and on cloudy days. Coming about twenty years after the first efforts to replace open fires with improved cooking stoves, the CooKit uses no fuel at all. The CooKit is both user-friendly and environmentally friendly. Families can save scarce, expensive fuel for when they cannot solar cook and when economically capable, add other, higher cost cooking improvements such as modern biomass, smoke hoods, biogas, or liquefied petroleum gas.

CooKit benefits

CooKit woman

Addressing fuelwood scarcities:

  • The CooKit saves more than four times its value in fuelwood each year. With careful use and storage, a CooKit can be used for two years, reducing fuelwood consumption by two tonnes.
  • Reduces pressure on forests for firewood and charcoal.

Improving health:

  • The CooKit can pasteurize household drinking water, making it safe to drink.
  • The solar cooking process is smokeless, reducing respiratory diseases and eye irritation.
  • Solar cooked foods retain vitamins, nutrients, and their natural flavors. There is no smoky taste; the foods cook slowly in their own juices. Nutritious, slow-cooking traditional foods (beans, root crops, and some grains) are restored to the family diet.
  • Cleanup is easy as the food never burns or sticks to the cooking pot.
  • Solar cooks frequently report that the money they save on cooking fuel purchases is used for many essentials, such as extra food, school supplies, and medical care.
  • Without having to gather wood or dung, breathe smoke, and tend a fire – all associated with traditional cooking – solar cooking is easy and safe for people with AIDS and other illnesses, the elderly, disabled, and young orphans.

Enhancing household and women’s economic status:

  • The CooKit represents a new opportunity for women to capitalize on an underserved market and better meet their own cooking energy needs.
  • Solar cooking saves time as there is less need to tend a fire or collect firewood. A person can cook while at work, at the market, or tending crops. Young girls can attend school instead of searching for fuelwood.
  • Solar energy is free and abundant in many areas of Kenya, providing a safe, clean, and healthy supplement to traditional fuels.

Co-developers are Roger Bernard of France and Barbara Kerr of the USA, with work also by Ed Pejack, Jay Campbell, and Bev Blum of Solar Cookers International. Extensive field tests in the USA and in many developing countries confirm its performance, convenience, low cost, acceptance, and adaptability to diverse needs.

Construction plans

Detailed plans

Solar Cookers-How to Make, Use, and Enjoy

Simple plans in other languages

German, Indonesian, Italian, Luo, Persian, Portuguese, Russian, and Spanish

If you can't find a large flat piece of cardboard or have difficulty laying out the fairly complicated measurements and angles, consider building one of the variations below.

PDF file for printing out a full-size template

Cookit on grid

You can download this PDF file to print out a full-size template at a copy center. You can then trace this template onto cardboard to make a CooKit. This eliminates having to lay out the pattern manually or print out the template in sections, and will simplify the construction process. Full-size CooKit template for printout

You can also download this PDF file to print out the full-size template on 25 pages of 8.5 x 11 in (standard US Letter size) paper. No resizing necessary - just open and print, then tape the pages together. Each page overlaps the next page by 10 mm (3/4 in) and has guide marks in each corner to help with alignment. Full-size CooKit template for printout - Tiled.

Using an existing CooKit as a template

See: How to make a CooKit solar cooker

Tips and tricks

  • To make clean straight folds in cardboard, first make a crease along the line with a blunt edge such as a spoon handle, then fold against a firm straight edge.
  • Make the slots a little too small and narrow so that they fit snugly to hold up the front panel.
  • To set up, lay panel flat with shiny side up. Fold up front and back parts and fit back corners into the slots in front.

Cooking directions

The pot

Put your food into a dark-colored pot with a dark-colored or clear lid.

Main article: Pots

Plastic bags and other glazings

Main article: Glazing
Ovenbagbox

Oven cooking bags are able to withstand temperatures of up to 315 °C (600 °F).

Place the pot inside a plastic bag or other clear enclosure. Close the open end of the bag and place pot and bag into the center of the cooker. When using two plastic bags, one inside the other, temperatures can increase up to 20 °C (68 °F) over what is reached using a single bag (source: SCN).

See tips below for using normal (non-heat-resistant) plastic bags. Note that when solar cooking conditions are very good, you may be able to cook without the use of a plastic bag around the pot.

Please note that if plastic bags have been outlawed in your country, there are many other ways to surround the cooking pot described in Glazing.

Cooking various foods

Choosing a cooking location

Set the CooKit on a dry, level surface in direct sunshine away from potential shadows. For best results, solar cooking requires continuous, direct sunshine throughout the cooking period.

Orienting the CooKit

  • Face the cooker ahead of the sun pointing to the location where the sun will be an hour later. This allows the cooker to cook most foods without needing to turn it to follow the sun.
  • When cooking beans or when cooking on a marginal day, you will need to turn the cooker at least once to keep oriented optimally.
  • FOR ALL-DAY COOKING, orient cooker so that it faces where the sun will be at noon or early afternoon. Food will be ready and waiting for the evening meal.

For recommendations of cooking times for specific foods, see Foods.

Adjusting the front flap

CooKit front flap adj

Raise or lower the front flap so there is a small shadow, no more than half its width, under it. The flap should be angled higher when the sun is high and lower when the sun is low. You want the front flap to reflect the sun, not block it.

Cooking on windy days

Main article: Wind protection
CooKit wind protection Iridimi 2007

Tying down a CooKit solar panel cooker so that it can withstand the winds at the Iridimi Refugee Camp where over 5,000 CooKits are in use.

Weighting down CooKit

On windy days, large stones or bricks can be placed on the edges of the CooKit, as well as under the front panel.

See also: Providing more support for the CooKit solar panel cooker - Ashok Kundapur

Care and storage

Store the CooKit in a safe place away from moisture and animals, preferably indoors. Allow plastic bags to air-dry or gently wipe dry with a towel. The CooKit is compact and portable. When not in use, it can be simply folded lengthwise into thirds or folded flat into a 33 cm (13 in) square.

CooKit folding steps

Tips and tricks

Wire stand Dr. Steven Jones found that raising the pot on a wire frame improved cooking in a panel cooker. It is also possible to set the pot on a clear glass bowl.
Glass bowls as pot stands Glass bowls and pie pans can be used to raise the pot off of the bottom of the cooker (note that the pot would normally be enclosed in an oven cooking bag when using a panel cooker). In some cases, they may provide more stability used upside-down.
Wire frame to keep normal plastic bag from melting Wietske Jongbloed created a simple frame to allow the use of normal plastic bags (instead of heat-resistant oven cooking bags).
Jose Albano bag frame Jose Albano created this frame to protect normal plastic bags (photo shows frame with bag removed).
Solar guard Dr. Ashok Kundapur has suggested a way to make a housing out of flat plastic sheeting. A bottom cylinder is supported by wire frame while a transparent cover, made of the same plastic material, makes access to the food very easy. This arrangement can also be used for retained-heat cooking.
Discarded phone cards to strengthen CooKit 1
Discarded phone cards to strengthen CooKit 2
Stephen Harrigan found that discarded plastic phone cards, which are readily available in Africa, worked well to strengthen CooKits in their most vulnerable areas. See also Making the CooKit more durable.
Notebook binding tape To remedy the moisture problem inherent in a product made of cardboard, the Solar Cookers International East Africa Office and colleagues have added notebook binding tape, also readily available in large cities or capitals to seal steno notebooks for students.
LogoNikwaxWaterproofing Nikwax has been used to waterproof and increase the durability of CooKits, reportedly extending the life of a CooKit by 50%. Its early use was in refugee camps in Chad as a result of a collaboration between Nikwax and TchadSolaire.
Friend of the Old bind CooKit edge

Friends of the Old (FOTO) staff members bind the edges of new CooKits to make them more durable in Katito, Lower Nyakach, Kenya. - C. Cross

  • Stephen Pearson reports: "We build CooKits in pieces using eleven small panels of cardboard. Shops even in rural areas have thin card stock available as scrap. These can be laminated together using local cassava glue (cassava is grown all over Africa) to form stiff panels, thus avoiding the need to import thicker cardboard. Join the eleven panels together with [5 cm] 2 in strips of worn-out dress or shirt (using the cassava glue). Protect the perimeter of the 11 panels with more [5 cm] 2 in strips ([2.5 cm] one in front and one in back to stop delamination of the cardboard). Let each panel dry properly. Then turn it over and glue on the aluminum foil to the side with no cloth hinge strips."


See also

Buying CooKits

Variations

European Solar Panel Cooker variation


European Solar Panel Cooker

The European Solar Panel Cooker (ESPaC) is a modification of the CooKit that is engineered to be most efficient in temperate latitudes (as opposed to the standard CooKit, which works best when the sun is high in the sky). Since the power of the sun rays is weaker at low-sun locations since the sun's rays have to traverse a thicker layer of air, the reflector material must be of high quality and high reflectivity. More information...

Manos Unidas variation


Manos Unidas Cocinalo II

Solar Cookers International's standard CooKit calls for a lot of curves, which can be hard to make with a hand held blade. Juan Urrutia Sanz of the Manos Unidas organization in Spain writes that his group promotes a variation on the CooKit shape that is easier for many people to make at home. The Manos Unidas version, called Cocinsol II. Señor Urrutia y Sanz reports that it cooks as well as the CooKit and actually has more reflective surface area. SCI's Jay Campbell agrees. Jay is an engineer who has chaired the SCI Research Committee and who worked on engineering the CooKit for manufacture in Kenya. (One key advantage of the CooKit's curved shape is that it is easier to figure out a way to fold it into an album-sized package for easy storage and transport.) To make your own Cocinsol II, use the shape and dimensions shown in the graphic. Cardboard is an inexpensive material to use which holds its shape and is also easy to fold. However, woven mats or baskets, molded plastics or wood can be used. The solid lines in the design show where to cut; the dotted lines show where to fold. Cover the surfaces of one side with shiny material such as aluminum foil or shiny gift wrap (which will reflect light to the pot at the center of the cooker).

High-Back variation


CooKit High Back variation

High Back variation

As part of their testing, Florida Solar Energy Center engineers redesigned the CooKit into a new geometry. The new design simply takes the same amount and type of material that makes up today’s CooKit and reconfigures it into a different shape. They dubbed it the “High Back reflector” because it has a back reflector that is much higher (i.e., taller) than the one in the standard CooKit.


Diassana variation


Diassana CooKit variation figure 1

Figure 1

Mr. Gnibouwa Diassana, of Bla, Mali, has been able to find sources for all the materials in or near Bla. “Cardboard is available in big towns,” he writes. “Plywood, glass, aluminum foil, sheet metal and plastic bags are available in Bla and neighboring towns.”

Diassana CooKit variation figure 2

Figure 2

Mr. Diassana also applies creative thinking to obtain low-cost materials. He notes that tea, a very popular beverage in Mali, is shipped from China in boxes lined with aluminum foil which can be recovered and reused for making reflectors for solar cookers. “It works well,” he says.

What is lacking in Bla, however, are large pieces of cardboard. To adapt to this problem, Mr. Diassana makes solar CooKits from five pieces of cardboard which he patches together using small thin pieces of cardboard (see Figure 1), or from pieces of satin fabric (glued or sewn into place to hold the large CooKit parts together (see Figure 2).

King variation


CooKit-arbitrary-units-v085

Detailed plan for building a CooKit of any size by using an arbitrary unit of measure.

Philip King writes of his variation:

I've made one CooKit and wanted to make more, but each time I've looked at the published plans I've found that they don't suit my way of thinking. I also find them difficult to scale to suit an arbitrary size of material. So, and in case there are others like me who get dizzy looking at all those angles and inches and centimetres, I've drawn my own design with the following intentions:

  • to use as few measurements as possible
  • to use an arbitrary unit that could be easily enlarged or reduced
  • to find all angles automatically
  • to use straight-line cuts throughout
  • to use as few cuts as possible (I could still lose a few)
  • to derive details easily without a template
  • to eliminate guesswork or fudging
  • to reduce the need for written instructions

I also wanted it to be as close as possible to SCI's classic and well-proven CooKit design but have some distinctive features of its own.

Of course, the production-line cookers are quite quickly made using templates, so this new plan has no advantage there. It is really intended to help those who are making a one-off cooker out of whatever randomly sized material they happen to get hold of.

2007-07-17-CooKits-pic4

A completed CooKit made with this design variation.

The design which follows is really meant for heavy corrugated board and not intended to fold to a small size (that's not to say it wouldn't if thin enough, I just haven't worked out yet how to derive the folds) and although the back angles are pretty close to the classic design they are different to a couple of degrees. The front panel is deeper and the back lower than in the classic, but not by much.

The chevron cuts in the ends of the side wings are to retain some surface area while also making the tabs narrower to fit the slots. I had an earlier design with a wider base and front panel to accommodate longer slots, but I like this one better, even though it adds a couple of cuts. The chevrons also satisfy my desire for a distinctive feature. The snips off the corners of the wings are to help with very stiff material when fitting the points into the slots; they don't really have to be measured, just a bit snipped off.

CooKit-arbitrary-units-v085-compare

Diagram shows how this design compares to the standard Solar Cookers International design.

The basic unit is the orange block, and a unit size of 1.5 in gives a sheet size of 48 in x 36 in. Clearly, a unit size of one inch makes a sheet size of 32 in x 24 in. Working in metric, a unit size of four centimetres yields a sheet size of 128 cm x 96 cm, which is about five percent larger than the 48 in x 36 in sheet.

I have also made this plan available as a PDF file.

Having just made a full-sized example from this plan I can confirm that it is fast and accurate. However, I know how it's supposed to work, so I would welcome comments from anyone who tries to follow this plan to build a cooker.

External links

Poly-Furnace variation


Plastic cookits during training in Sudan

The Poly-Furnace is made of polypropylene flute board.

In February 2008, Stephen and Sheila Harrigan shipped 275 of these durable plastic CooKits to the Sakali Refugee Camp in Sudan. The Poly-Furnace is a cut down model of the CooKit made by Solar Cookers International. Because of the adverse living conditions of the refugees in Darfur, Sudan, the cardboard CooKit will not last much more than six months to a year. The need to have a durable CooKit has prompted us to develop one made of plastic polypropylene flute board. Reflective aluminum polyester is attached to the surface before it is cut and formed. A local group of volunteers have begun to make these for introduction into Sudan in 2008.

See also Making the CooKit More Durable.

Wooden variation


Wooden CooKit

This CooKit is made of wood covered with aluminum foil.

Eagle variation


Eagle pieces

Pieces for the Eagle variation of CooKit.

The Eagle Solar Cooker was designed in 2007 by Manda specifically for Americans. It is made of eleven pieces which begin as 21.5 cm x 28 cm (8 1/2 in x 11 in, USA standard letter size) paper. Intended for students and beginners, it is easy to construct; no protractor or compass is used. An optional twelfth piece (of a whimsical eagle head) can be added at the top.

Aluminum panel variation


Hans and Petty Heerebout, founders of Solar Cooking Project Zambia, have experimented with an aluminum panel version of the CooKit. They feel the cooker is able to reflect more light than the standard CooKit and is more weather resistant.

Solar Cooking Project Zambia aluminum CooKit

An aluminum panel CooKit.

Teong Tan variation


Teong Tan Cookit variation photo 11-11

Teong Tan CooKit variation

Teong Tan CooKit assembly instructions 11-11

Teong Tan CooKit variation

Here are several ideas for modifying the CooKit. First, the size of the cooker can be reduced so that more cookers can be made from the same amount of construction material. Second, the panel locking feature can be relocated so that the two sides of the front reflector can be tilted to reflect more sunlight towards the desired direction. The modified CooKit is structurally more robust, and can be positioned upside down to cook when the sun angle is low. The cooking pot receives more reflected sunlight under the normal operating range of the cooker. The modified CooKit can be folded down into a small package for easy transportation and storage just like the original design. Review more of Teong's description at: Teong Tan variation layout diagrams

Modified_CooKit_Solar_Cooker

Modified CooKit Solar Cooker


An enthusiast has submitted photos of the Teong Tan variation positioned to capture low sun angles and also in the standard overhead orientation. He was able to do some winter cooking in Ottawa, Ontario, Canada, (latitude 45° N) and had the cooker reach 180 °C (285 °F) in the vertical position, using a pot inside a clear pyrex container.

Round-back variation


Rollins Standard Deluxe Cooker

Rollins Standard Deluxe Cooker available from Applied Green Technology.

The Rollins Standard Deluxe Cooker is a waterproof panel cooker that is very similar to the CooKit. It is being mass-produced in the UK by Applied Green Technology, and is available in very large quantities.

Haines Solar Cooker variation


Main article: Haines Solar Cooker
Haines Solar Cooker, 11-17-14

The Haines Cooker (version II).

The Haines Solar Cooker is made of IXPE (cross-linked polyester) foam insulation bonded with reflective metalized polyester film (MPET film / 3mm IXPE foam / white PET film). The reflective polyester will not oxidize, cannot be scratched off, and has a high melting point. Importantly, the new material is easy to recycle and is environmentally safe through the whole production and recycling process without pollution. In the USA, this material is used to make high-end auto windshield sunshades.

Two-pot CooKit variation

Two pot cookit

The Two-pot CooKit variation.

This simple idea was suggested by a soldier serving in Afghanistan (Colin Hoskins).

Gasy Nahandro variation


Main article: Gasy Nahandro
Gasy Nahandro back, 4-20-13

The Gasy Nahandro grass woven CooKit.

This CooKit variation makes use of local materials to create a very affordable cooker. It was designed by Dominique Dutoit for use in Madagascar. The panels are constructed from woven grass mats, and then covered in reflective material. The target is to make the cookers for less than USD 2.00 and be able to offer them through local retail stores.

Quickie Demonstration CooKit

Quickie CooKit illustration, 4-29-13

The Quickie Demonstration CooKit assembly.

You can make this “quickie” version of the CooKit on the spot for teaching purposes. It only cooks small quantities of food, but it can be used to demonstrate water pasteurization, etc. It is not intended as a substitute for a standard solar cooker.

It involves cutting a typical cardboard box (about 0.6 x 0.6 x 0.3 m, or 2 x 2 x 1 ft) in half diagonally. Then add a cardboard flap in front and cover the inside with tinfoil.

One Sheet variation


Kundapur variation


Solar-cooker-design-Cookit easy plan

Xuni variation


The Xuni CooKit variant

This is another multi-pot variation of the CooKit, designed and tested by the Proyecto Olla Solar in cooperation with the Mexican Fund for the Conservation of Nature.  Initially tested using a mylar reflective material, the Xuni reached a temperature of 85 °C (185 °F) in three hours.

Cook-n-Go


The Cook-n-Go variation was designed and manufactured by the now defunct Aftarkeia Network located in Greece. The panels are made of wood and are hinged together. When folded the package is quite compact.

Cook-n-go panel cooker, 5-14-14

Cook-n-Go solar panel cooker.

A Simple CooKit


Simple Solar CooKit

Simple Solar CooKit layout

Royal Botanic Garden or Jordan variation


CooKit - Jordan Royal Botanic Garden variation

Instructions in English and Arabic for building a CooKit out of smaller pieces of cardboard designed by the Royal Botanic Garden of Jordan:

Audio and video

  • August 2012:
SOLAR_COOKIT-INTERNATIONAL_WATER_AND_HEALTH_ALLIANCE

SOLAR COOKIT-INTERNATIONAL WATER AND HEALTH ALLIANCE

A CooKit demonstration.

  • February 2009:
Solar_Cooking_with_the_CooKit

Solar Cooking with the CooKit

Ever thought that maybe - if we did just one thing each day towards sustainability - we could make a difference? Inspired by a documentary about solarcookers.org and the CooKit, Taoseña Melody Romancito gives it a whirl with a potato-carrot curried stew.

  • April 2008:
Cooking_in_Sakali_Refugee_Camp_in_Darfur

Cooking in Sakali Refugee Camp in Darfur

The solar cooker students from last year are training their neighbors in the Sakali Refugee Camp near Nyala South Darfur, Sudan.

  • March 2008:
Kyoto_Protocol_-_Al_Gore,_but_what_can_YOU_do_for_the_world?

Kyoto Protocol - Al Gore, but what can YOU do for the world?

Video showing how to make the Solar Cookers International version of the CooKit.

  • February 2008:
Tusk_Trust_Documentary_-_13_Solar_Energy

Tusk Trust Documentary - 13 Solar Energy

Tusk Trust documentary of introducing the CooKit in Kenya in 2008.

  • September 2007:
CARE_Germany_Solar_Furnace_in_Chad_Solaröfen_für_Tschad

CARE Germany Solar Furnace in Chad Solaröfen für Tschad

The CooKit being used in Chad refugee camp.

  • The link below shows the animated result of a simulation of a cross-section of a CooKit. It does not include the power from the side reflectors.
Click here to play CooKit Profile Video
  • This video shows the power contributed by the side reflectors. The display picture shows a view of each reflector. Each reflector is divided into pixels. Each pixel corresponds to an elemental area of the reflector. Black pixels define the extent of the reflector, with a white line representing the boundary between the rear and front portion of the reflector. Pixels corresponding to elemental areas from which reflected sun rays hit the pot are shaded. Rays from the white pixels hit the top of the pot, rays from dark gray pixels hit the side of the pot, and rays from light gray pixels hit the bottom of the pot.
Click here to play side reflector video

Articles in the media

See also

NGOs using CooKits

  1. Obia Solar CooKit Group
  2. Adventures in Health, Education, and Agricultural Development
  3. Association des Femmes Ingénieurs du Mali
  4. Association Malienne des Femmes Handicapées
  5. Earth Passengers
  6. Student Solar Cooking Science Project
  7. ET-Solar Tech
  8. Friends of the Old
  9. Fundación Inti Uma Ecuador
  10. Solar Cookers International
  11. Girl Guides Association of Malaysia
  12. Japan Solar Energy Education Association
  13. Lejofonds
  14. Lotan Center for Creative Ecology
  15. Rotary Club of Fresno
  16. Trust in Education
  17. Solar Cooking KoZon
  18. Solar Connect Association
  19. SUPO
  20. Sustainable Utilization of Renewable Energy
  21. United Village Transformation
  22. NAREWAMA
  23. Lady Fatemah Trust
  24. Mount Kenya Energy Project
  25. FairClimateFund

External links

Photo Gallery