Evaluation of environmental factors and equipment configuration on efficiency of a solar soil water collector

The aim of this paper is to assess the effects of environmental factors and equipment configuration on the recovery of soil water using a solar collector. The recovery of water from soil is difficult, since the energy requirements are very high. Solar energy provides a solution to this problem, especially in countries with high solar radiation. In the current study, it was found that the amount of water collected depended largely upon the air temperature and soil water content. In winter, 0.465 L m^-2 day^-1 were collected compared to 1.163 L m^-2 day^-1 in summer. The initial soil water content was equally important; dry soil tended to yield less condensate than wet soil. Saturated soils yielded 0.814 L m-2 day-1 in winter compared to 1.395 L m-2 day-1 in summer. The type of soil (i.e. gravel, silt and loamy sand) affected the release of water from the surface, as a result of differences in soil water release characteristics. The air space between the soil surface and the condensate collecting surface also had an effect on condensate collection; the larger this distance, the greater the amount of condensate that was collected. The configuration of the condensate collecting surface also had an effect on the amount of condensate obtained; the shallower the slope of the surface, the greater the amount of condensate that was collected. The collector was most effective in summer, on cloudless days, with wet poorly- drained silt soils.