Impact of Sky Temperature Models on Photovoltaic Panel Energy Yield Estimation

The efficiency of photovoltaic (PV) panels, determined by irradiance and operating temperature, depends on thermal interaction with the environment. Solar radiation is the main thermal input, whereas energy conversion, convection, and radiation fluxes are the primary heat dissipation mechanisms. Radiation fluxes are based on boundary temperatures, such as ground and sky temperature, making accurate sky temperature estimation essential. However, despite its importance, there is limited work comparing the available models, which are often either very simplified or highly complex and adapted to specific geographic conditions. This article examines five sky temperature models and their impact on estimating the operating temperatures of PV panels. Experimental validation shows that variations in sky temperature estimates lead to significant differences in panel operating temperatures. Although the effect on energy generation estimates is smaller, the findings highlight the importance of accurate sky temperature models for better PV performance predictions. This study provides a basis for improving PV energy yield forecasts through enhanced sky temperature modeling.