The cooling effect of floating PV in two different climate zones: A comparison of field test data from the Netherlands and Singapore

Abstract

© 2020 International Solar Energy Society An enormous area could potentially be unlocked, when more photovoltaic (PV) systems would be deployed on water bodies. Especially in densely populated areas this opens a pathway for PV to contribute to the energy transition in a large scale. Another potential benefit of floating PV (FPV) systems is that they can outperform conventional PV systems in terms of energy yield due to the cooling effect from the water. However, there is very little field data available to quantify the cooling effect and compare it across different climatic conditions. The research presented here has thoroughly studied this effect and translated it into an estimated specific yield comparison between conventional and floating PV systems. The study is based on field tests that are located in two different climate zones: a temperate maritime climate (the Netherlands) and a tropical climate (Singapore). Irradiance weighted average temperatures of FPV systems have been compared with a land-based system in Netherlands and a rooftop system in Singapore as references. The best performing FPV systems showed 3.2 °C (Netherlands) and 14.5 °C (Singapore) lower weighted temperatures compared to their benchmarks. Open system designs, where the PV panels of the floating system are widely exposed to the water surface, lead to an increase in the heat loss coefficient of floating PV panels (a measure for the cooling effect) of up to 22 W/m2K compared to reference PV systems. Annual specific yields of the PV systems were estimated by the measured irradiance-weighted temperature difference and by a PVsyst model with inputs of the heat loss coefficients. Based on these calculations, we observe that the gain in energy yield from the cooling effect of FPV systems compared to the reference PV systems is up to 3% in the Netherlands and up to 6% in Singapore.