GENERAL RULE :- Since ‘Solar Cooking’ is all about converting sunlight into Heat by having it strike a dark object, the pots should as a general rule be dark – preferably matt BLACK. If you have no black pots or are unable to find any don’t panic all is not lost, your current pots can be blackened. They should be of thin metal ( stainless steel or alumunium) with a well fitting lid. Cast iron or clay pots are not recommended as they take too long to heat up. There are variations to these rules and will be explained later.
How to MAKE your pots BLACK . Finding black cookware is no easy matter so we can make our own. A camping person who regularily cooks on an open fire will know that when pots are left exposed to a wood fueled fire they will darken by the smoke and soot of the flames. These are the perfect colour and texture for maximum heat production. If your only utensils are bright stainless steel or aluminium, they can be darkened with black paint. Your local hardware store will stock a suitable heat resistant paint (eg ‘Pot Belly Black’ or ‘Engine Enamel’ etc)
What Cookware To Use and Where :-
Different Solar cookers have differing cookware requirements.
The ‘BOX COOKER’. There are two box designs ‘A’ – all internal walls and base black. The cookware can be any colour because with this design, sunlight enters the box, is converted to heat by the blackened walls and base of the box which then heat the air within the box, which finally heats the pot. ( the pot is heated by convection as in a conventional domestic oven ). In this design rays of sunlight enters the box, are bounced around by the reflective walls until they strike something Black which then converts them into heat. In this case the pot and lid must be BLACK and ‘B’ – reflective walls with only the base black .
The ‘PANEL COOKER’. Since all the panels are made of reflective material the cookware must be BLACK and being the least powerful of all the designs I recommend placing the cookware into a plastic oven bag (a heat trap) while cooking to prevent heat loss to the atmosphere.
The ‘PARABOLIC’. In my collection I have two distinct designs. ‘A’ – the store bought unit which has a broad spectrum focal point that heats the pot from all sides. Pots should be all BLACK and ‘B’ – recycled TV satellite dish converted into a cooker which has a narrow focal point ( 10 cent coin diameter ) pointing at the base of the cookware which sits on an adjustable shelf. Only the base needs to be BLACK.
To Summarise :-
1 – To be safe the cookware should be BLACK
2 – the cookware should be placed in a plastic Oven Bag if using a ‘panel cooker’
3 – Always cook with the pots etc sitting on an open metal Grille or Trivet and not sitting directly on the cooker base.