Solar hybrid systems with thermoelectric generators

The possibility of using of thermoelectric generators in solar hybrid systems has been investigated. Four systems were examined, one working without radiation concentration, of the traditional PV/Thermal geometry, but with TEGs between the solar cells and heat extractor, and three other using concentrators, namely: concentrator - TEG - heat extractor, concentrator - PV cell - TEG - heat extractor, and PV cell - concentrator - TEG - heat extractor. The TEGs based on traditional semiconductor material Bi2Te3 and designed for temperature interval of 50-200 degrees C were studied experimentally. It was found that the TEG's efficiency has almost linear dependence on the temperature difference Delta T between its plates, reaching 4% at Delta T = 155 degrees C (hot plate at 200 degrees C) with 3W of power generated over the matched load. The temperature dependencies of current and voltage are also linear; accordingly, the power generated has quadratic temperature dependence. The experimental parameters, as well as parameters of two advanced TEGs taken from the literature, were used for estimation of performance of the hybrid systems. The conclusions are drawn in relation to the efficiency at different modes of operation and the cost of hybrid systems, as well as some recommendations in relation to optimal solar cells for applications in these systems. (C) 2011 Elsevier Ltd. All rights reserved.