| Boiling Point No. 05 - September 1983 |
SOLAR COOKER FROM ZIMBABWE
We must apologise to Brian MacGarry ('Alternative Cooking Stoves - Zimbabwe in BP No 4) for misinterpreting two separate drawings he sent us of the solar cooker, and combining them to arrive at a cooker with a door too small for the pot inside! We had assumed the cooker was a 'top loader' but the traditional African dish of sadza or ugali must be stirred about 30 minutes before serving, and to remove the pot through the lid to do this would lose too much heat from the cooker, so the side door is necessary.
Mr MacGarry bases his choice of cooker sizes on the requirement of 1,000 sq cms of glass 'window' in the top for each litre capacity of the pot. This is on the assumption that, at that latitude, a flat plate inclined at 25 degrees to the horizontal, and facing north, will receive between ' and 6KWh / day / sq m all the year round.
So the popular 3 litre enamel cooking pot requires a cooker 'window' of 55cm by 55cm, and the door is 20cm square which will not admit a larger sized pot. A 2 litre size pot requires a 'window' of 45cm x 45cm, and a door 17 cm high by 18 cm wide.
Mr MacGarry points out that for most climates in many inhabited areas of the world, the cooker would need to be even larger relative to the pot. He provided us with brief details of his glass area calculations, which we will be pleased to supply - or which could be obtained from him in greater detail.