This solar cooker has been designed by Suresh Vaidyarajan - an architect, who has found a simple solution for a tough problem. For the last one year he has been cooking his food in this solar cooker. This is the simplest solar cooker I have ever seen.
Old car tube.
Aluminum cooking vessel
Take an old car tube. If the tube is punctured get it patched. Inflate the tube and keep it on a wooden board.
Take an aluminum cooking vessel with a lid. Paint it black from the outside. Put all the ingredients for cooking Khichdi - rice, daal, salt, water etc. in the cooking pot.
Place the cooking vessel inside the tube. Cover the tube with a piece of plain glass. Within three hours the Khichdi will get cooked.
What happens? The place in the well of the tube is like a closed cavity. Air neither go out nor come in. The rays of the sun enter the glass and get trapped. Slowly, the temperature of the cooking vessel rises and the Khichdi gets cooked.