Energy Co-Generation in Photovoltaic Thermal-Collector (PVT) System: A Significant Increase in Efficiency

Abstract

The main obstacle of using the earth’s enormous solar energy potential is its low conversion efficiency. The  conversion efficiency from solar irradiation to electricity by the photovoltaic (PV) cell is around 5–20%. The remaining energy that falls on the PV surface becomes waste and increases the PV surface temperature. In this experimental work, we have modified a solar Photovoltaic (PV) system into a Photovoltaic-thermal collector (PVT) co-generation system and examined the effects on its performance. A coolant (water) has been circulated underneath the PV surface to extract heat and keep the PV surface temperature low. In the modified system, a glass cover was also placed on the top of the PVT to minimize the heat loss. This study found that electrical efficiency of the PV decreases linearly with surface temperature. In the modified PVT, when heat is extracted from the PV surface, the total efficiency increased to a significant level (i.e. 82%). The top loss of the PVT system was minimised effectively by putting a transparent glass cover on the PVT top. Although the top cover glass of PVT costs about 1% of electrical efficiency due to the glass’s transmission factor, it significantly increases thermal efficiency i.e. from 48 % to 75%. The overall efficiency (electrical and thermal) of the co-generation system is much higher than the standalone PV or solar collector system.