Experimental and environmental assessment of a photovoltaic/thermal-PEM electrolyzer system for hydrogen and low-grade heat cogeneration in a hot-arid climate

Integrating photovoltaic/thermal (PVT) cooling with proton exchange membrane (PEM) electrolysis offers a promising approach for green hydrogen generation by simultaneously recovering the low-grade thermal energy and improving photovoltaic electrical performance. Despite its potential, the performance of integrated PVT-PEM systems under high irradiance and high temperature conditions typical of arid regions has not been sufficiently investigated. This study experimentally evaluates the hybrid PVT-PEM system under outdoor conditions in Dhahran, Saudi Arabia. The system was instrumented to continuously record solar irradiance, electrical power, coolant flow rate, temperature, and hydrogen production rate. The experimental results show that PVT cooling increases PV electrical efficiency by 6 to 12% relative to an uncooled PV system, with the largest improvement observed under high solar irradiance and subsequently high surface PV temperature. Consequently, hydrogen production rates increase up to 10% at high solar irradiance levels. Sensitivity analysis further reveals that increasing the coolant flow rate raises the recovered thermal power from 0.6 kW to 1.3 kW and improves the PV electrical efficiency from 13% to 14.5%. The maximum solar-to-hydrogen efficiency achieved by the PVT-cooled system was 10.2% compared with 9.2% for the uncooled configuration, corresponding to an 11% improvement.Under average operating conditions, the PVT system delivered approximately 450 W of electrical power and 2000 W of recovered thermal power, corresponding to electrical, thermal, and overall PVT efficiencies of 14%, 50%, and 62%, respectively, evaluated at ṁ = 0.05 kg s−1. The average specific energy consumption for hydrogen production is about 45 kWh/kg. In addition, the proposed system is estimated to reduce carbon dioxide emissions by 1.65–1.88 tCO2/year, or 49.39 – 56.46 tCO2 over a period of 30-year lifetime. These outcomes clearly highlight that the PEM-PVT hybrid system is a promising solution for producing both green hydrogen and useful heat energy, enhancing solar energy utilization and supporting sustainable energy transitions in hot-arid regions.