Effect of optical, geometrical and operating parameters on the performances of glazed and unglazed PV/T system

Highlights: • Three-dimensional dynamic model is developed to investigate the performances of a hybrid PV/T. • Performances comparison of glazed and unglazed systems is done under different conditions. • The glazed system provides 21.49% of thermal efficiency higher than unglazed collector. • The electrical efficiency of the unglazed PV/T is 11.78% higher than glazed system. • The optical properties of glass cover have a significant effect on the PV/T performances. This work aims to investigate the effect of optical, geometrical and operating parameters on the thermal and electrical performances of both glazed and unglazed hybrid PV/T solar collector. To achieve the goal, a three dimensional mathematical thermal model is developed and solved numerically using implicit finite difference method. In addition, an optical analysis is performed to calculate the optical efficiency of the solar system. The model accuracy is tested by comparing the obtained results with experimental and numerical data available in the literature. The results show that the glass cover system is an important element of the photovoltaic-thermal system. It is found that the thermal efficiency of the glazed system is $21.49\text{\%}$ at $0.01kg/s$ mass flow rate higher than unglazed system, but its electrical production is lower than unglazed collector by $11.78\text{\%}$. It is obtained that the thermal and electrical yields are dropped by $18.07\text{\%}$ and $15.93\text{\%}$ respectively when the refractive index of glass increases from 1.1 to 1.9. The extinction coefficient of glass has also a significant effect on the hybrid system performances. However, the glass thickness has a slight impact on the collector efficiency.