Evaluation of the Feasibility of a Multi-Purpose Solar Roof Still in the Virgin Islands

摘要

One approach to the chronic water problems of the Virgin Islands would be widespread use of small solar stills to augment private water supplies. A study was done to: (a) identify critical resource and design factors; (b) estimate the local potential for solar distillation; (c) test the efficiencies of several designs; and (d) determine the production and economic potential of small locally built stills. The design parameters examined were: Deep vs. Shallow Basins, Glass vs. Plastic Covers, 'Roof' vs. Flat Collectors, and rooftop placement. Results of the study shows that the solar energy in the Virgin Islands is not only at a high level but that the level is constant. In the stable Virgin Islands environment, the most simple flat plate, uninsulated collector is nearly as efficient as a complex expensive one. The lowest production was about 0.6 gal/sq ft/day; the highest 0.96 gal/sq ft/day. The average was about 0.8 gal/sq ft/day. Using the figure and 2 cents/gallon purchased water, a 20 sq ft still would supply 20% of a family's needs and have a payback period of less than one year.