Numerical Investigation of a Hybrid Photovoltaic Thermal PVT Module

Abstract

Over 173,000 terawatts of solar radiation continuously strike the Earth’s atmosphere however, most of this energy is reflected or absorbed and is lost due to insufficient space and technology required to harness the solar energy and generate electricity. Photovoltaic (PV) solar panels are widely used globally to receive light energy from solar irradiance and convert it to electricity. PV cells are designed to absorb as much as 80 percent of the insolation energy however, due to structural limitations only 10-15 % of this incident solar radiation is converted to electricity with most of this absorbed energy converting to heat and raising the temperature of the entire module and greatly reducing the efficiency of electricity generation. This undesirable reduction in electrical efficiency is avoided by the addition of a heat recovery system to the PV module to cool the panel and effectively extract waste heat to enhance both thermal and electrical efficiency. Such modified PV modules are known as hybrid PV module or Photovoltaic thermal systems. The primary purpose of this research is to numerically validate the effectiveness of various ribbed surfaces in enhancing the thermal efficiency of the dual hybrid PVT system by simultaneously using both air and liquid water as cooling fluids. In addition, the effect of water and air velocities on thermal efficiency have also been observed by monitoring the temperatures at water outlet. The findings indicate significant reduction in the water outlet temperature with increasing water velocity and decreasing air velocity drawing the conclusion that the air velocity maximized, and water should be passed at a low velocity to achieve higher heat transfer rates. The utilization of ribbed surfaces substantially improved thermal performance with the semicircular and triangular ribbed surfaces achieving higher water outlet temperature at all solar heat flux throughout the day. Highest water outlet temperature and thus heat transfer was observed to be occurred at 1:00 P.M when the heat flux from the sun is maximum. The numerical findings successfully conformed with the data obtained from the experiment and conform to the results from previous research works. Finally, this study provides a comprehensive comparison between the different geometries of the PVT module and determines the optimum operating conditions for optimized thermal efficiency of the PVT module.