Temperature Dependent Performance of Solar Photovoltaic and Thermal Hybrid Systems

Abstract

Solar photovoltaic-thermal (PVT) hybrid systems have the high potential to be an effective and viable method for producing electricity and thermal energy for low grade heating application. The hybrid system is highly energy efficient with improved electrical efficiency due to cooling of solar cells and gained thermal energy due to heat absorbed by the fluid from the heated cells. Nevertheless, the utilization of these systems is not growing rapidly due to the controversial operational problems, as well as installation and maintenance difficulties in comparison with general separated photovoltaic (PV) and thermal systems. In this paper the operating temperatures of solar cells in PV and PVT collectors in dependence of ambient temperature are investigated. On the base of comparison of operating temperatures of solar cells of PV module and PVT collector the effectivity of PVT system application is assessed. It is shown that there is a ‘critical’ minimum value of ambient temperature below which the PVT system cells have the higher temperatures than the cells in PV modules (‘reverse’ process) and the application of PVT system is not reasonable. The dependence of “critical” temperature on the type and thermal characteristics of PVT system is investigated. The proposed methodology for PVT hybrid systems effectivity assessment can be used by scientists and designers during the development of different hybrid PVT systems.