Abstract: The operating temperature of photovoltaic (PV) modules has a direct effect on electrical performance and short-term efficiency under real outdoor conditions. During periods of strong solar irradiance, PV modules are exposed to considerable thermal stress, which increases operating temperature and can reduce power production. In this study, the thermal behavior of a photovoltaic system under high-temperature operating conditions was analyzed using a set of empirical and semi-empirical thermal models. The analysis included the classical Ross/NOCT model, a wind-corrected NOCT formulation, an irradiance-adjusted NOCT approach, and the Faiman thermal model. In addition, a semi-empirical Thermal Performance Deviation Model (TPDM) was developed to investigate the combined influence of irradiance and thermal excess on PV thermal-performance behavior. The results showed pronounced daily thermal cycling and significant temperature rise during peak irradiance periods, with modeled operating temperatures exceeding 60°C under the most thermally stressed conditions. The estimated short-term thermal efficiency loss reached 10.83%, while more than 1100 operating hours exhibited efficiency losses above 3% and 552 hours exceeded 5% thermal efficiency loss. The proposed TPDM formulation achieved the best overall statistical performance, with an R2 value of 0.857 and an RMSE of 0.724, indicating reasonable agreement under variable outdoor operating conditions. The analysis additionally demonstrated the important role of wind-driven convective cooling in reducing thermal stress during outdoor PV operation, highlighting the importance of thermal stress analysis under high-temperature conditions.

Keywords: Photovoltaic systems, PV thermal modeling, operating temperature, Thermal efficiency loss, Ross model, Faiman model, NOCT model, Thermal stress analysis

Pages: 365-378