Researchers in Portugal found that Iberian heatwaves can cause sharp but short-lived PV yield losses, mainly during peak temperature hours due to module heating and inverter derating.
Scientists from the University of Évora in Portugal have analyzed the performance of three photovoltaic plants in Spain and Portugal during four extreme heat events recorded between 2024 and 2025. They found that heatwaves can cause significant yield losses concentrated during the hottest hours of the day, while also exposing limitations in conventional methods used to forecast PV energy production.
High temperatures reduce the efficiency of crystalline silicon modules by around 0.3% to 0.5% for each degree Celsius above 25 C. During heatwaves, module temperatures can exceed 70 C, accelerating the degradation of encapsulants, cables, and other components, while also triggering thermal derating in inverters.
In the study “Analysis of photovoltaic power plant resilience under Iberian heatwaves,” published in the International Journal of Climate Change Strategies and Management., the researchers explained they analyzed hourly production data from three PV plants: Zebro in Portugal (37.06 kW), Ariza in Zaragoza, Spain (15 kW), and Amibil, also in Zaragoza (64.5 kW).
