Numerical and experimental analysis of a new direct-contact PVT system for sustainable energy production: Energy, exergy, and environmental assessments

This study proposes a new photovoltaic-thermal system (PVT-S) in which water is directly connected to the rear of the photovoltaic (PV) module, eliminating the traditional absorber plate in order to improve thermal management, reduce pressure losses, and lighten the system's structure. This configuration addresses the issues of temperature inhomogeneity, thermal expansion, and excessive weight observed in conventional PVT-Ss, highlighting its importance in improving the performance and durability of hybrid solar systems. The proposed configuration was studied numerically using the finite element method in COMSOL Multiphysics, then validated experimentally under real environmental conditions in El Jadida for different mass flow rates, analyzing temperature distribution, pressure losses, energy and exergy performance, as well as several sustainability indicators such as waste exergy ratio (WER), sustainability index (SI), ecological efficiency index (EcEI), and improvement potential (IP), in addition to exergy destruction and entropy generation. The results indicate that this configuration demonstrates improved temperature distribution and lower pressure loss (18.16 Pa) at a high flow rate of 0.0500 kg/s. Furthermore, at a flow rate of 0.0417 kg/s, the maximum temperature difference, power output, and electrical efficiency between the PVT-S and the reference PV panel are 25.38 °C, 19.03 W, and 1.46%, respectively. The mean energy-exergy efficiencies of the PVT-S reach 75.83% and 17.56%, respectively. The peak values for SI, WER, IP, and EcEI are 1.21311, 0.85402, 1089.47 W, and −0.64865, respectively. These results suggest that the proposed configuration is an effective solution for simultaneously improving the energy performance, exergy quality, and overall sustainability of PVT-Ss.