Rear-surface water cooling for photovoltaic panels: A thermo-hydrodynamic pathway to high-efficiency and sustainable solar power in hot climates

Photovoltaic (PV) modules functioning in high-temperature environments face considerable efficiency declines as a result of increased cell temperatures, driving the need for innovative and resource-efficient cooling solutions. This study explores the rear-surface water cooling of photovoltaic modules through a coupled thermal–hydrodynamic numerical model, aiming to identify crucial design and operational parameters that influence thermal and electrical performance. The model undergoes initial validation using published experimental data for air-cooled PV systems, followed by an extension to include rear-surface water cooling as an added convective boundary condition. A thorough parametric analysis is conducted to evaluate the effects of duct height, flow regime, inlet water temperature, and climatic conditions on the reduction of module temperature and the improvement of electrical efficiency. The findings indicate that implementing rear-surface water cooling can lower the operating temperature of photovoltaic systems by as much as 20% in hot urban environments, resulting in enhancements in electrical efficiency ranging from 15% to 20%, contingent on the hydraulic configuration employed. The analysis further illustrates that suitable duct geometry and flow management facilitate efficient cooling while minimizing water usage, underscoring the practicality of closed-loop operation. The proposed framework offers a physically consistent approach for designing and optimizing rear-surface water-cooled PV systems, effectively addressing significant limitations found in current studies that overlook the interplay between thermal and hydrodynamic effects. The results enhance the development of scalable PV cooling solutions tailored for hot climates and provide direction for future experimental validation and techno-economic evaluation.