Experimental investigation of the effect of using metal-oxide and boron based nanoparticles on performance in a photovoltaic thermal (PV/T) collector

Renewable energy sources are constantly on the agenda today because the fossil fuels used are limited and the need for energy is constantly increasing. Considering the energy need and environmental problems caused by fossil fuels, it will continue to maintain its place on the agenda in the future. Among these resources, solar energy has an important position. Nowadays, heat energy and electrical energy production from solar energy is common. Photovoltaic (PV) solar panels can convert a limited portion of the solar energy falling on them into electrical energy. The heat created by solar energy that cannot be converted into electricity in PV panels reduces electrical efficiency. Photovoltaic thermal (PV/T) collectors are used to remove this heat from the system and at the same time convert it into useful energy. Some of the PV/T collectors are liquid cooled. It is common to try to increase the efficiency of the system by using different fluids in liquid-cooled PV/T systems. Some of the studies were carried out with forced circulation (using a pump) and some with natural circulation (thermosiphon effect). In this study, a natural circulation indirect heated PV/T system was designed. Different concentrations of Al2O3, ZnO and BN nanoparticles were added to the water circulating in the PV/T collector in order to increase the efficiency. System performance was evaluated according to different parameters such as solar radiation, outdoor air temperature, fluid inlet and outlet temperature. According to the experimental results, an increase in thermal efficiency and total efficiency (thermal + electrical) occurred with the addition of nanoparticles to the cooling liquid in the PV/T system. The highest total yields were obtained as 58.25%, 52,626% and 47.6% in ZnO, BN, Al2O3, respectively, in experiments using 0,03 g/L concentration of nanoparticles. In the panel without cooling, the efficiency was only 14.14% in terms of electrical efficiency. The highest exergy efficiency and sustainability index were determined as 17.155% and 1.207, respectively, at 0.03 g/L concentration of ZnO nanofluid. According to the study results, it was concluded that passive cooling PV/T systems are suitable for use in houses, dormitories, factories and hotels.