The effect of plane booster reflectors on the performance of a solar air heater with solar cells suitable for a solar dryer

Abstract

We present a theoretical study of a solar photovoltaic-thermal (hybrid) system consisting of a flat-plate solar air heater mounted with solar cells and a plane booster. A conventional flat-plate collector is converted into a hybrid system by mounting solar cells directly on the absorber plate. A hybrid system is self-sufficient in the sense that the electrical energy required by the pump is supplied by the panel. Such systems are well suited to applications such as solar drying. The combined system is analysed for the case when the radiative and absorptive properties of the cell surface and the absorber plate are nearly the same. The solar cell efficiency is a linearly-decreasing function of the absorber plate temperature. The performance of the system has been evaluated for various combinations of boosters. The minimum area of the solar cells required to run the pump at a given flow rate has been calculated as a function of time, with and without boosters. The minimum cell area required decreases with the use of boosters. High cost cells may be replaced by low cost reflectors. The solar air heaters presently available on the market are not suitable for direct conversion to hybrid systems.