Floating vs. ground-mounted PV in semi-arid climates: an experimental analysis of tilt angle, cooling effects, and evaporation rates

Abstract While the portion of photovoltaics (PVs) in the worldwide energy transition is rapidly increasing, the large land requirements of solar power plants and efficiency losses due to high operating temperatures are among the main challenges faced by the sector. In this context, floating PVs stand out as an innovative solution that both prevent land-use conflicts and increase panel efficiency through the cooling effect of fluid. In this study, the performance of floating PVs was examined in comparison with ground-mounted systems through an experimental setup established in the study area, which has semi-arid climate features. This research offers a unique contribution by analyzing not only the installation type but also the effects of panel tilt angle on thermal efficiency, power generation, and water conservation potential. Experimental findings proved that the natural cooling effect of water kept floating PV panels significantly cooler than ground systems in all configurations. Particularly at an 8° tilt angle, the cooling effect was maximized due to the proximity of the panels to the water surface, resulting in an average reduction of 4.2 °C and a maximum decrease of up to 10 °C in panel temperature compared to the ground system. This thermal advantage directly impacted photovoltaic cell efficiency, with the 23° tilted floating PV system providing the highest performance gain tested, achieving a 1.8% efficiency increase compared to its ground equivalent. Hydrological analyses revealed that the 8° tilt angle effectively shaded the water surface, reducing evaporation by 37.5%, but this rate decreased to 12.5% when the angle increased to 38°. In conclusion, the study suggests that arid regions should be preferred over classic latitude-based optimum angles for floating PV applications.