Experimental investigations on unglazed photovoltaic-thermal (PVT) system using water and nanofluid cooling medium

The electrical and thermal performance of an unglazed photovoltaic thermal (PVT) system integrated with a serpentine coil configured sheet and tube thermal absorber setup was evaluated using water and copper oxide-based nanofluid. An uncooled PVT system reached a maximum panel temperature of 68.4 °C at noon and obtained an average electrical efficiency of 12.98%. Water and nanofluid cooling of the PVT system reduced the panel temperature by 15 °C and 23.7 °C at noontime, respectively. Compared to the uncooled PVT system, the average electrical efficiency of water and nanofluid cooled PVT system increased by 12.32% and 35.67% to obtain 14.58% and 17.61%, respectively. The thermal efficiency of the nanofluid cooled PVT system (71.17%) was significantly higher than water cooling (58.77%) due to maximum heat absorption by nanoparticles. It was also observed that the overall efficiency of the nanofluid cooled PVT system was 21% higher than the water-cooled system. Also, obtained the highest primary energy-saving efficiency for the nanofluid cooled PVT system.