Design and performance analysis of hybrid photovoltaic-thermal grid connected system for residential application.

Abstract

High output electrical energy is obtained from photovoltaic (PV) systems subject to high irradiance. However, at high irradiance, the efficiency of PV systems drops due to increase of the temperature of the systems. In order to improve the efficiency of photovoltaic systems, much effort has been spent on developing hybrid photovoltaic thermal (PVT) systems using water as a coolant to withdraw heat from solar modules. This research is focused on the study of the behavior of hybrid PVT collectors using rectangular channel profiles which provide a large surface for heat exchange between PV panels and thermal collectors unlike the circular channel profile used in conventional PV systems. In hybrid PVT systems, coolant water circulates in a closed circuit by means of the thermosyphon phenomenon and the heat from this water is extracted from a storage tank and can be used in hot water systems instead of an electric geyser. Numerical models of water velocity in channels due to the thermosyphon phenomenon and the temperature of solar modules was developed and a system was designed for modest Durban household demand. A simulation was run for specific summer and winter days comparing a conventional PV system and a hybrid PVT system. The results were very encouraging, and demonstrated that the equipment is capable of extending the PVT application potential in the domestic sector where more than 40% of electricity cost is heating water.