CFD modelling to derive U-values for floating PV technologies with large water footprint

•CFD applied to derive U-values for floating PV technologies with large water footprint.•Floats with large water footprint promote a significant non-uniform temperature field in the module wafer layer.•The importance of the water temperature for the U-value is small with the cell temperature reduced less than 1 °C.•Confirmed that U-values are negligible influenced by solar irradiation, air temperature and water temperature.•An equation for U-value that scales linearly with the wind velocity is presented.