Article by Joanne Brannan June 2012 Home Farmer
Many solar cookers are either complicated to construct, very expensive to buy, or suitable only for climates far sunnier than ours here in the UK. But there is one simple solar cooker design that costs next to nothing to build and works remarkably well, even here!
When lined up with the sun, the solar funnel cooker focuses solar energy on an area towards the bottom of the funnel reflector, but not on a single spot, so there is no risk of burning – an ever-present danger with the alternative parabolic solar cooker. A preserving jar painted black to absorb the sun’s rays acts as a simple pressure cooker, heating the contents up faster than a simple covered container. A surrounding clear plastic oven bag acts as a ‘greenhouse’ to further enhance the heating effect.
WHAT YOU NEED TO BUILD YOUR SOLAR FUNNEL COOKER
All the things you need to build this solar cooker are inexpensive and readily available. You may even have most of them in your home already!
* A large piece of cardboard (the bigger, the better). The side of a large corrugated cardboard box is ideal.
* High-temperature matt black paint, such as barbeque paint. Check that it is suitable for use on glass.
* A Kilner (or similar) preserving jar, complete with rubber seal.
* An oven bag (the sort used to contain a roast chicken), large enough to easily contain the jar, and a wire bag tie. You can use an ordinary plastic bag of the type used for vegetables in supermarkets, but it may melt if it touches the hot black jar.
* Glue. Ordinary paper glue, or even flour and water paste, is fine.
* Everyday kitchen aluminium foil.
* A block of wood on which to rest the Kilner jar during cooking.
* String or wire to fasten the cardboard funnel edges.