Most solar cookers work on the basic principle: Sunlight is converted to heat energy, that is retained for cooking. Sunlight is the "fuel." A solar cooker needs an outdoor spot that is sunny for several hours and protected from strong wind, and where food will be safe. Dark surfaces get very hot in sunlight, whereas light surfaces don't, therefore black or dark pots should be used; best in dark, shallow, thin metal pots with dark, tight-fitting lids to hold in heat and moisture. A transparent “heat trap” around the dark pot lets in the sunlight, and keeps the heat that is produced from escaping. For the Coookit a clear, heat-resistant plastic bag or large inverted glass bowl is used.
The advantages are the low cost, the easy transportability; they are light and compact; the fact that for most areas in the developing world Cookits can be manufactured locally, thus creating jobs, local ownership and production while reducing the need for large amounts of petrol in transportation.
It is also an advantage that the food is cooked slowly, as it allows for extra hours where women are not required to tend a fire or search for firewood. These added hours can be used for other income generating activities, such as working on ones farm and increase produce; working with other women to initiate a poultry farm; pig farming or other entrepreneurial, artisan activities.
The disadvantage of the Cookit is that it is made with cardboard, which if exposed to regular moisture and water, will damage it and it will no longer be functional. If it is kept out of water and well maintained, it will last longer.
The requirement of the plastic bag is also an obstacle in that these bags can be reused, but will eventually need to be replaced. Again, the number of times these bags can be reused varies on the specifics of each household. When a plastic bag is poked or ripped, it is no longer viable. In areas where water is scarce, if a pot spills while removing it from the bag, cleaning the bag can be difficult and reduce its length of use. These plastic bags and the need to consistently replace them is perhaps one of the main disadvantages of this solar cooker. SCI and other organizations and engineers are working to expand our research to develop and improve this CooKit, while keeping the cost low and increasing the durability and problems with the plastic bags.
Want to try the CooKit for yourself? Download instructions to build your own: http://saveone.net/#1365880/Cookit-Solar-Cookstove-An-Affordable-Solution-that-Doesn-t-Need-Fuel!