Exploring the influence of extreme atmospheric variables on PV electricity generation in a metropolitan area

This study explores the influence of extreme atmospheric conditions on the electricity generation of a 750 Wp single-axis tracking polycrystalline photovoltaic (PV) systems, operating in the complex urban climate of Istanbul. While existing literature predominantly evaluates PV performance under Standard Test Conditions (STC) using low-frequency data, this research utilizes high-frequency (1-min) field measurements to capture transient meteorological anomalies. Focusing on two contrasting boundary months (August and February), the study employs z-score standardization and stratified tail-distribution analysis to systematically isolate mean operations from extreme generation events (e.g., μ + 1.5σ and μ – 0.5σ). The quantitative results reveal critical deviations from standard models. Under extreme high-generation conditions in August, severe thermal stress (cell temperatures >40 °C) causes massive efficiency attenuation, while wind speed provides vital convective cooling up to an optimum threshold of 5 m/s. In contrast, under winter peak conditions, relative humidity exhibits a counter-intuitive enhancing effect by optimizing diffuse light capture. Furthermore, the assumption that wind universally benefits PV efficiency is disproven; winter wind speeds exceeding 3.5 m/s induce an adverse overcooling effect, preventing the panels from reaching their optimal 25 °C operating temperature. Ultimately, this study highlights that atmospheric extreme tail-events fundamentally alter PV performance dynamics, providing essential insights for optimizing system design and realistic energy forecasting in metropolitan Mediterranean environments.