Development of low-cost reflective plate thermal energy absorber systems for application in South Africa

Abstract

An innovative solar heat collector system was developed from low-cost materials by applying innovative design technology and using adaptive technologies. The system design entails placing long black polymer pipes connected in series circulation, mounted and positioned in grooves of inverted box rib galvanised steel plating. The grooves reflect and focus the incident rays on the centre piping, concentrating incident sun rays on the black piping and increasing the absorption of thermal energy in the piping filled with circulating water. The circulation of the water is facilitated by a direct-current solar-driven pump powered by a small photovoltaic panel. The thermal energy as collected is stored in a standard household geyser tank. A 3 × 4 m heat absorber of this type collects approximately 10 kWh of energy per day. The estimated cost of the system, considering the capital outlay over an expected ten-year life cycle for the product was estimated at R0.25 per kWh. This pricing competes extremely favourably with the general cost of grid electricity in South Africa for medium-sized households, which is of the order of R2 per kWh up to 1000 kWh per month, including taxes. With an estimated electricity cost escalation of above 5% every year, the ten-year saving for a household using this prototype can be approximately R200 000. The technology and designs developed through the study can create many new business opportunities in South Africa in both urban and rural environments, through manufacturing, installing, repairing, and maintaining the systems.