How does a solar cooker work?

A solar cooker is essentially a well-insulated box with a window made of glass or plastic through which the sun rays can get in. Inside, the bottom and walls of the cooker are covered in black to absorb the sunlight and release it as heat. Black cooking pots should be used to increase the heating effect. In Africa, temperatures up to 170°C or slightly higher can be reached this way.

Advantages of solar cookers

1. The manufacture is simple, inexpensive and the device requires very little maintenance, lasting up to 10 years.
2. Cooking this way is free. Thus, it is possible to save on fuel costs and amortise the investment on a solar cooker in a short time period.
3. A solar cooker is suitable to cooking, baking, refining, making fruit or vegetable preserves, drying and sterilising water and medical equipment.
4. It is also possible to produce creams, soaps and snacks.
5. Cooking and baking works very well: since the higher temperatures are limited to about 170°C the food cannot burn. This also means that it is not necessary to always be around the cooker tending the fire, which provides valuable time for other tasks.
6. Deforestation and CO₂ emissions are reduced since less wood needs to be burned.
7. In many African countries, where thery is plenty of sun but poor economies, solar cookers can be real help to increase the survival chances of both people and the forests, with their rich biodiversity. Plus, the cookers can also become a source of extra income.

Disadvantages of solar cookers

1. They are better suited for places with strong sun exposure and long days, like the subtropics and highlands.
2. Cooking time is about twice as long as with a conventional stove, although this is compensated by the time that becomes free since solar cooking requires much less supervision.
3. The greatest difficulty when promoting solar cookers in developing countries is to move people away from the habit of cooking with open fires. Nevertheless, this new environmentally-friendly technology has been successfully deployed in several locations (see Projects).

Diversity of models In addition to the original types, sometimes called "cooking box" or "solar owen", there are many other models like parabolic reflectors, hybrid designs, funnel reflectors or drum cookers (made with one half of an oil barrel). There is also a different working principle for solar driers. Other designs can be seen in solarfood.de, www.eg-solar.de and www.solarcooking.org.