The solar oven does not use gas, firewood or electricity: the heat that cooks the food comes directly from the sun, whose rays multiply when meeting the mirrored surfaces of the oven. Of course, despite reaching surprising temperatures, making it possible to bake a cake in an hour and a half, the solar oven is totally dependent on the weather condition and, therefore, it is not possible to think that one day everyone will have a home. But in poor regions, mainly in Africa, where the sun is constant and firewood accounts for almost 100% of the energy consumed, solar ovens can bring about a true revolution. Firewood has at least two major problems associated with its use as an energy source: its “harvesting” destroys ecosystems and its burning releases carbon gases, which pollute the air and intensify the greenhouse effect. The solar oven is not only capable of cooking without polluting, but also sterilizes the water in a mere 20 minutes, when it reaches 65ºC, the temperature necessary to kill all microorganisms capable of causing illness. And the best thing is that each person can build their own solar oven, spending almost nothing. The simplest model, panel type, is made with a piece of cardboard, coated with some laminated paper. In 1990, the international association Solar Cookers distributed ovens of this type to 28,000 families in Kenya and, eight years later, found that around 20% of them still used the panels as their main equipment in the “kitchen”. Almost 6 thousand families, who would be burning firewood, have adopted sustainable cooking.
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HOT PLATE
The parabolic shape makes this type of oven reach the highest temperatures among solar ovens – some guarantee that they cook as quickly as a conventional oven. This happens because, thanks to its shape, the sun’s rays converge to the same point, where the pan, baking sheet or teapot should be placed.
COME TO THE BOX
The box-type oven has the advantage of being more sheltered and having a large internal volume. It consists of a wooden box, with the interior coated with a reflective material and a glass lid (which produces the greenhouse effect inside the box). More sophisticated models have reflective flaps on the outside, directing the rays towards the interior.
SIMPLE AND EFFICIENT
The panel is the simplest model and, despite looking fragile, you can cook anything on it. To facilitate cooking, it is recommended that you use a dark ceramic pan, wrapped in plastic to prevent heat from escaping.
To build a panel-type solar oven, just cut a piece of cardboard in the format shown below, cover it with aluminum foil – if you have thicker laminated paper, even better – and fold it according to the drawing. In five minutes you have an oven ready to cook