A solar oven cooks by turning light rays from the sun into heat. The sun is the fuel source. Reflectors on the solar oven direct the light towards a dark pot because its dark color absorbs the heat. The pot is placed inside a glass or plastic cover that allows a little bit of space to retain the heat. The most basic solar ovens can reach about 300 degrees F, and the most sophisticated ones can cook at much higher temperatures. Of course, the solar oven will not work at night or on a cloudy day, since it relies on the sunlight to work.
Box solar ovens are the easiest type of solar oven to make or buy. They can be made from wood, cardboard, plastic or metal. Basically they are a box in which the dark cooking pot is placed. The top of the box is a reflector that can be adjusted to make the rays hit the inside of the oven. These box ovens may need to be moved when the sun changes its position to get the most consistent heat. Parabolic solar ovens can be large enough to bake all the bread for a bakery to sell. They are also called concentrators. They are large curved concave and very shiny metal reflectors. The dark pot fits in the middle. Usually these parabolic ovens can be rotated to catch the best of the sun's angles for cooking. They get so hot that it is important to have only trained people using them. The third type of solar oven is called a panel oven. It is really a mixture of the box oven and the parabolic oven. It has a cavity, like a box oven, where the pot goes. It has a curved reflector, like the parabolic oven, to collect and point the sunlight.
Since solar ovens do not require any fuel other than the sun, they are becoming very popular in the developing nations in Asia and Africa especially. They don't cost a lot so many charitable organizations have begun helping to distribute them to people in areas without other options for power. Inexpensive versions are being marketed to campers so that they do not need to use fire when they are cooking outdoors. Solar ovens are inexpensive and environmentally responsible cooking solutions for people all over the world.