rating solar cookers

at the 3rd international conference on solar cookers use and technology there was further discussion about standards for comparing solar cookers. going beyond what can be done in laboratories there is an ongoing effort to refine test methods and criteria for decision making in the field to select the best solar cooker(s) for particular sites, conditions and consumers. for technical performance criteria it might offer simple tests that can be easily done without special equipment. it would also include other critical factors such as the following.

cost: the cost of all supplies needed for the solar cooker - including estimated replacement parts needed within five years, is compared to the cost of alternative cooking methods and the fuel used in them over five years. if the solar cooker becomes cheaper than alternatives in just a few months, it is likely it can compete in local markets.

convenience: the cooker either needs little or no attention during cooking or the instructions spell out clearly how often adjustments are needed during a cooking period (for example with parabolic cookers turning to track the sun or stirring to prevent burning). if movable, is it easy to move, easy to store?

safety: the cooker is incapable of starting an accidental fire inside or outside the cooker. breakable glass includes warning where small children may be at risk. in the case of concentrator cookers, no risk for accidentally blinding eyes or burning hands at the focal point.

heating, cooking capacity: the cooker heats a specified amount of water such as one liter from ambient temperature to boil in specified time such as one or two hours midday when the sun is at least halfway up (45 degrees above the horizon). it should cook a meal for at least a small family, and/or specify size of family it should cook for. see also standard tests in ecscr guides above. for alternatives to measuring water temperatures with expensive thermometers or thermocouples: use two whistling teapots (idea from the gambia) or use sci water pasteurization indicators (wapis or saf-wats). in some areas it may be important for the cooker accommodate a wide variety of bread pans, cookie sheets, covered bowls and pans.

durability, maintenance: repairs should be infrequent and/ or possible to do without special equipment. repair parts should be easy to get. there should be instructions for ordinary maintenance needed (such as wiping off dust from windows and reflective surfaces). information should indicate expected durability under various weather conditions, and/or guides for protecting it when weather may damage it. there should be instructions for making repairs and getting replacement parts (for example cookit bags, glass windows for box cookers).

wind stability: the cooker should be reasonably stable in wind to avoid spilling food, or should include instructions to easily make it so (for example placing rocks in specified places).

instructions: should give clear guides for estimated length of cooking time and variables that influence cooking time (food quantity, wind, etc.)