Thermal and electrical performance of an evacuated hybrid solar collector *

Energy consumption is steadily increasing with the ever-growing population leading to a rise in global warming. Building energy consumption is one of the major sources of global warming, which can be controlled with renewable energy installations. This paper deals with an advanced evacuated hybrid solar photovoltaic-thermal collector (PVT) for simultaneous production of electricity and domestic hot water (DHW) with zero carbon emissions. Most PVT projects focus on increasing electricity production by cooling the PV.  However, in this research, increasing thermal efficiency is investigated through vacuum glass tube encapsulation. The required area for conventional unglazed PVT systems varies between 1.6-2 times of solar thermal collector for similar thermal output. In the case of encapsulation, the required area can decrease by minimizing convective losses from the system. In this concept, the electrical productivity was slightly affected due to an increase in the surface temperature of the PV with the vacuum tube. The performance of evacuated PVT is compared to air-filled and unglazed PVT, simulated using ANSYS 18.1 at different mass flow rates and solar irradiance. The simulation results with evacuated tube PVT show thermal productivity of 0.82 kW/m², which is 41% higher than the conventional unglazed system. Whereas, electrical productivity is comparable with all three systems at 140 -150 W/m².