Solar drying is done at 3 major levels: the 1st one is the family or small social group that consumes much of its own produce and sells to the local market; the 2nd is the small enterprise or co-operative that sells to the local market as well; and the 3rd is the medium and large enterprise that sells to far away markets and exports. Solar drying is an economic activity that is normally involved in a market mechanism. There are several types of market, for example: local market which mainly requires low drying cost and better quality than sun drying; larger market and international markets which mainly require high quality standards; market of dried products where products dried in different ways are competitors of solar dried products; and market of solar driers where other different methods of drying are competitors.
A solar box cooker is designed to receive and trap direct solar radiation, reduce heat loss from conduction, radiation and convection and store heat gained for long periods of time. Sunlight, both direct and reflected, enters the solar box through the glass or plastic top. It turns to heat energy when is is absorbed by the dark absorber plate and cooking pots. This heat input causes the temperature inside of the solar box cooker to rise until the heat loss of the cooker is equal to the solar heat gain. Temperatures sufficient for cooking food and pasteurizing water are easily achieved. The material used can be quite cheap and portable, including cardboard or a shallow pit in the ground, straw, rice husks or other dried vegetation, aluminium foil or scrap tin, and scrap glass and perspex. A non-portable cooker is built of earth and brick and may be double-glazed.
It is reported in 1996 that solar ovens are becoming an accepted form of cooking in Afghan culture, and knowledge of solar cooking is widespread in certain areas of Afghanistan resettled by refugees who learned to use solar ovens while in refugee camps in the Northwest Frontier Province, Pakistan or Kabul during the previous decade.
In the Dadaab Refugee area, almost directly on the equator in northeast Kenya near the Somali border, the 100,000 refugees find gathering fuelwood increasingly difficult and dangerous. A development agency (GTZ) funded by the German government has introduced fuel efficient cook stoves, fireless "haybox" cookers and tree planting. In the past, the 35,000 refugees in the Kakuma Refugee Camp in northwest Kenya had to barter away part of their meagre food rations for enough fuel to cook the remainder. In 1996 it was reported that over 1,200 families are able to solar cook and solar pasteurize milk and water. Of the refugee women who became solar cooks, 24 volunteered for extra training so they could teach their neighbours.