Numerical approach of an advanced hybrid photovoltaic thermal system based on exergy, energy, enviro-economic, and sustainability factors

Abstract

• PVT systems with direct contact between water and PV cells have been studied for the first time. • Sustainability and enviro-economic indices for different mass flow rates and solar radiation are obtained. • Energy and exergy analysis for different mass flow rates and solar radiation are obtained. • The position of the fluid inlet, the height of the water slick, and that of the water distribution manifolds were optimized. Conventional photovoltaic thermal systems (PVT-Ss) suffer from several limitations, including the use of heavy and expensive heat exchangers, the lack of direct contact between the heat transfer fluid and the photovoltaic (PV) cells, as well as problems associated with the absorber plate, such as increased weight, high cost, and thermal expansion. To overcome these limitations, this study proposes a novel PVT-S configuration. This innovative concept eliminates the absorber plate, allowing direct contact between the water and the PV cells, reducing costs, weight, and pressure drop. A parametric analysis evaluated the effects of the fluid inlet position, water slick thickness, and the height of distribution manifolds on temperature distribution, pressure drop, energy, and exergy performance. The influence of irradiation and water flow rate (FRT) on these indicators was also examined. A sustainability assessment was also conducted, encompassing both environmental and economic impacts. The three-dimensional modeling of the system was performed using COMSOL Multiphysics, based on the finite element method (FEM). The best performance was achieved with a lateral inlet, a manifold height of 30 mm, and a water slick thickness of 1 mm, yielding a thermal efficiency of 81.27%, an electrical efficiency of 13.76%, and an overall exergy efficiency of 16.51%. As the water FRT increases, the annual reduction in CO₂ emissions improves by 1.02 tCO₂/year, accompanied by an approximate 28% increase in environmental cost. Meanwhile, the system’s sustainability index decreases slightly, from 1.19774 to 1.17247, representing a reduction of 0.02527.