Performance enhancement of concentrated PVT system via indirect PCM precooling medium of water integrated with hydrogen production: Techno-economic evaluation

Integrating low-concentration photovoltaic-thermal systems with hydrogen production systems offers a promising solution to enhance energy efficiency and mitigate climate change by reducing thermal emissions. The current study proposes a novel low-concentration photovoltaic-thermal system coupled with an indirect phase change material, a passive precooling medium, for integrating inlet water temperature (PVT/PCM) with a hydrogen production system, compared to a conventional water-based PVT system. Two different phase change materials, RT8HC with an average melting point of 8 °C and SP24E with an average melting point of 24.5 °C, are used for winter and summer simulation. The electrical and thermal performance of the novel system with/without phase change material is studied under different concentration ratios and mass flow rates. The suggested system's mathematical model is solved using energy balance as its foundation, programmed based on a self-developed MATLAB code. Both systems' generated power and hot water are utilized for hydrogen synthesis through electrolysis, facilitating a direct comparison of their energy outputs and hydrogen generation rates. The results show that integrating a precooling medium (indirect phase change material) enhances the power generated by the PVT/PCM system compared to a water-based PVT system for summer operation by 1.2%. In the PVT/PCM technique, increasing the concentration ratio to 4 improves generated power by 200.8%, compared with non concentrated case (C=1), while increasing mass flow rates to 150% at a concentration ratio of 4 enhances electric power by 1.95% compared to the baseline flow rate. The PVT system incorporating a precooling phase change material exhibits higher thermal and electrical outputs; however, the estimated hydrogen production cost is $7.88 per kg for the PVT/PCM configuration.