Review of recent research on photovoltaic thermal solar collectors

Photovoltaic (PV) technology can be categorized as a mature technology but its performance with its elevating temperature has a negative effect and opens a new area of research which led to the introduction of photovoltaic thermal collector (PVTC) systems. PVTC systems integrate PV modules and solar thermal collectors in a single unit to derive energies from uninterruptible solar sources. This review article is limited to the design and development of the heat exchangers used in typical air and water-based PVTC system. Heat exchangers are used to improve the heat transfer from the back surface of the PV module, thereby improving its overall efficiency. The review shows that for air-based PVTC, the electrical efficiency with various types of heat exchangers lies in the range of 4-24%, whereas for water-based PVTC is 5.1-15.8%. The maximum thermal efficiency achieved for the water-based system is observed to be 72% against the 87% for the air-based system indicating that a significant approach has been made in the air-based system with the novel concept of the heat exchangers as compared to the water-based system. At the end of the paper, some future recommendations are also commented on to make the PVTC system more viable.