Performance Assessment and Improvement of Photovoltaic-Thermal System based on Energy, Exergy, Economic and Environment Analysis

A photovoltaic thermal (PV/T) system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency. A 4E analysis method (includes energy, exergy, economic, and environmental aspects) was formulated to comprehensively evaluate the performances of the PV/T system, combining experimental and simulation studies. Firstly, the experiment was performed using water as the cooling medium. Results show that the PV/T system can reduce daily CO2 emissions by 1682.47-1705.98 g, and compared to the PV system, the added cooling module can increase electrical efficiency and environmental performance by 12.19% and 6.2%, respectively. When the mass flow of water rose from 0.017 kg/s to 0.023 kg/s, the electrical, thermal, and overall efficiencies were improved by 3.82%, 11.36%, and 8.27%, respectively. Secondly, a numerical simulation model was constructed based on the experimental results to predict operations of the presented PV/T system using nanofluids as the cooling medium, including Ag, Al2O3, and SiO2. Simulation results show that the Al2O3-nanofluid-based PV/T system has a higher application value, enabling an electrical efficiency of up to 15.13%. Its thermal efficiency can be enhanced by 5.43% when the volume fraction of Al2O3 increases from 1% to 5%.