Historical and recent development of photovoltaic thermal (PVT) technologies

In the context of climate change in the world at the global level, various actions are taken for the development of renewable Energy and particularly solar energy which have potential for future energy applications. The current popular technology converts solar energy into electricity and heat separately. The photovoltaic thermal (PVT) system is designed to generate thermal and electrical energy simultaneously. A major research and development work on the photovoltaic thermal (PVT) hybrid technology has been done since last 30 years. Different types of solar thermal collector and new materials for PV cells have been developed for efficient solar energy utilization. The photovoltaic (PV) cells suffer efficiency drop as their operating temperature increases especially under high insolation levels. The overall electrical efficiency of the photovoltaic (PV) module can be increased by reducing the temperature of the PV module by withdrawing the thermal energy associated with the PV module. Both water and air either by forced or natural flow has been used for PV cooling through a thermal unit attached to the back of the module yielding photovoltaic thermal (PVT) collector. The main purpose of heat extraction unit is to extract heat from the photovoltaic system and keep its temperature at satisfactory level so that it can work efficiently. Till date many researchers have done a lot of work and number of studies have been carried out in designing, simulation, modeling, and testing of these systems. This paper reviews on the state and development of PVT technology around the world but the studies includes experimental and analytical are mainly focused on photovoltaic thermal technologies at the Indian subcontinent. (C) 2014 Elsevier Ltd. All rights reserved.