Experimental investigation of the efficiencies of PV and PVT-water solar collectors

In this study, tempered glass was used instead of polyvinyl fluoride type tedlar which is used in photovoltaic (PV) panel construction. The PV panel and the photovoltaic/thermal hybrid (PVT-water) panel produced from the same PV panel for providing rapid cooling of the PV cells. Thus, an increase in electricity production was attempted. The differences in electricity production and water temperature in the newly produced glass PV panel and PVT-water collector were experimentally measured at the same environmental conditions. With these measurements, conversion of PV system to PVT system and efficiency comparison were also discussed. The surface temperature in the PV panel is directly proportional to the radiation. In analysis, evaluation of thermal and electrical performance of PVT and PV systems is discussed. Between September 18, 2019 and November 9, 2019, analyzes were conducted for the obtained values of radiation higher than 800 W/m2, the day of peak radiation and average weekly values. Three different mass flow rates of 0.05 kg/sec, 0.1 kg/sec and 0.15 kg/sec were circulated during the tests. In PVT, higher outlet water temperature values were obtained with the circulation of small mass flow rates. The highest thermal efficiency was obtained for the highest mass flow rate of 0.15 kg/sec. The lowest thermal efficiency was recorded for 0.05 kg/sec mass flow. Higher efficiencies can be obtained by circulating low mass flow rates for inlet and outlet water temperature differences. In PVT system a mass flow rate of 0.05 kg/sec is recommended to achieve higher temperature differences. In PV and PV panels, nearly equal results of elektrical efficiency were recorded during the test period. Since, the temperature of the upper and lower cells of PVT was measured at the same temperatures as the PV during the measurements, the electrical efficiency for PVT could not be achieved more than PV. Keywords: Glass to glass panel, PV panel efficiency, PVT-water panel efficiency, solar energy