Solar energy for domestic use

Abstract

The demand for pool heating has increased dramatically over the last few years. This is ascribed to the idea that a swimming pool is expensive and can only be used for four months of the year. Therefore, a need for a relatively inexpensive solar heating system, capable of heating pool water to comfortable temperatures for an extended period, does exist. The least expensive solar heating system for swimming pool heating on the market in South Africa is in the order of R 11000. This is a fixed system, usually mounted on the roof of a house. In order to ensure the safety of minors, a safety net or sail must be installed. This is an additional cost, which approximates R1500, yielding a total cost for safety and heating in the order of R 12500. Copper pipes packed in black material are utilised in these conventional heating systems, and it is the cost of this good heat conductor that makes these units expensive. In this study an alternative pool heating system constructed of PVC was investigated. The system is designed to be flexible, mobile, act as a safety mechanism and absorbs the maximum amount of solar energy available. Dark blue material as opposed to black PVC was selected for aesthetic reasons at the expense of maximum efficiency. The material strength was tested as well as the strength of adhesion. The influence of factors such as exposure to the sun and the effect of water containing chlorine and acid on the material were evaluated. Also, various means of channelling the water through the system for increased efficiency was investigated. A pilot model was constructed and its performance evaluated. It has been concluded that the alternative approach provides effective heating at a lower cost than current systems. Also, the durability of the design was found to be acceptable.