Most of the solar cookers used in the developing world are box type. The higher performance parabolic cookers are extensively used by households only in Tibet (mirror area about 2m²). Elsewhere, they are most often used in large configurations in schools and other community kitchens where big mirrors can be used to cook tens of litres of food at once (eg ULOG solar hybrid community kitchen with mirror area of about 7m²).

The price tags of the Chinese/Tibetan cookers exceed $100 and the ULOG cookers exceed $1000 and so are not affordable by ordinary people. This paper describes a design that can be fabricated by rural people with their existing skills. Its performance is not so good as the Chinese and ULOG models but is considerably better than box cookers which cost more because of the high cost of glass.

A working model has been made by rural, illiterate Nepalise women belonging to the untouchable caste. Participants for this project and a larger project including other types of solar cookers were chosen, based on their skills, by local women's committees set up with support from a Plants for Life (a Nepalese NGO) integrated rural development programme.

A local, skilled bamboo weaver wove two parabolic baskets about 1 m diameter each, ie 0.8m² using a metal former. A mixture of clay, cow dung, mustard oil cake and paddy husk was pasted on to the parabolic baskets and left to dry for a day. Next day, this was smoothed with fresh mustard oil cake and left for another day. On the third day the surface was polished with sandpaper, and aluminium, reflecting paper was glued on. (See figure 1)

A supporting frame was made with the help of a local carpenter using bamboo to hold the baskets and also to move them vertically from about 30 to 90 degrees. Using a mirror. the two reflecting baskets were focused on an oven plate and the cooking pot.

During cooking, adjustments were made every 12 to 15 minutes. Vertical adjustment was done by using a moving bamboo mechanism.

The material cost of the 60kg cooker was US$3 and labour for the prototype was 18 hours. Cooking time was 35 minutes for 0.5kg of rice and 40 minutes for 0.5 kg of potatoes.

This work was financed from FINNIDA NGO funds.
Last edited by Miriam Hansen .
Page last modified on Monday October 4, 2010 14:43:42 GMT.
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