Solar cookers, also known as solar ovens, can be an interesting and effective way to cook foods using the power of the sun. There are many ways to make a solar cooker, but the fundamental principles are the same. Solar cookers work by reflecting the sun's rays into a contained area which traps the generated heat. With strong, direct sunlight and a properly built solar cooker, the heat builds to temperatures high enough to cook almost any food that can be cooked in a conventional oven.
Some solar cooker designs have become quite complicated and are recommended only for a knowledgeable and advanced user, but there are simple and easy ways to make a solar cooker with minimal time and materials. To make a solar cooker, you will need two boxes, one slightly smaller than the other, aluminum foil, black construction paper, plastic wrap, and newspaper. You may also need tape and a pair of scissors.
First, the lid should be cut off of the smaller box. The smaller box should be placed inside the larger one, and the space in between the two boxes should be filled with newspaper. Next, the center portion of the lid of the larger box should be cut out so that the outer portions of it remain covered, covering the area holding the crumpled newspaper, and the middle should be cut away to reveal the inside of the smaller box, which serves as the cooking area.
Next, you should line all sides of the interior box with a smooth layer of aluminum foil to reflect the heat of the sun. Black construction paper should be put on the bottom of the interior box, which will help absorb more of the sun's heat. When cooking, the top of the interior box should be covered with plastic wrap or a sheet of glass in order to let ample sunlight into the cooking area. The window should be completely sealed to prevent any heat from escaping while you are cooking.
To maximize the amount of sunlight entering the cooking area, a flap should be created that folds up from the top of the larger box. The flap should be lined with a smooth layer of aluminum foil. It should then be adjusted so it reflects a maximum amount of sunlight into the cooking area.
Once you make a solar cooker and you are ready to cook, the food can be placed into the cooking area just as you would place food in a conventional oven. Boiling water in a container placed in the cooking area is also possible. It is possible to make a solar cooker that achieves temperatures hot enough to cook food, but it will take longer to warm and will not get quite as hot as a conventional oven, so cooking times may be twice as long as normal. Individual solar cookers vary, so over time you will become familiar with yours.