ABC Rural: The Solar Nest
Caleb Cluff, Australia, February 2007
The "Solar Nest"
A very low-cost oven-type solar cooker has been developed by blending the user's needs, cooking objectives and available materials to achieve basic cooking requirements.
The [linked] photos show the "solar nest" that was used for testing the concept of a very cheap solar cooker. The nest could be made of any fibrous material, such as leaves, rags or straw. The cooking vessel should be dark metal, preferably a baking dish, and covered by a transparent material, such as glass or plastic to reduce heat loss from evaporation.
The glazing material on top of the nest can be plastic or glass, about 500mm square. If plastic is used, it should be "double glazed", that is, two sheets with an air gap of about 20mm. This reduces heat loss from conduction and convection to compensate for the greater radiative heat losses than glass. Tedlar plastic is better than PV but not as good as glass; it is very tough and durable and reasonably cheap (about $3-$5 for a cooker). The cooker gets about 10°C hotter with a metal plate underneath the cooking vessel.
See ABC Rural Blog