Hotspot-Induced Performance Degradation and Safety Risks in Aged Polycrystalline Photovoltaic Modules Evaluated Using IEC 61215 Standard

Abstract

This study presents a quantitative assessment of early stabilization losses and hotspot-induced degradation in polycrystalline photovoltaic (PV) modules following IEC 61215 procedures. Six new 100 W modules were subjected to controlled outdoor stabilization under cumulative irradiance exposures of 5 and 10 kWh/m², while ten aged 260 W modules exposed for two years under open-circuit (Voc) conditions were evaluated under induced partial-shading hotspot stress. Electrical performance was characterized under standard test conditions (STC) using I-V measurements, complemented by infrared thermography and visual inspection. Stabilization testing revealed maximum power (Pmax) reductions of 3-5% after 5 kWh/m² and up to 10% after 10 kWh/m² exposure, with fill factor decreases of approximately 1-2%. In aged modules, hotspot activation produced localized temperatures exceeding 90 °C, surpassing the IEC acceptance threshold of 85 °C. Post-stress measurements showed irreversible Pmax losses ranging from 8% to 17%, accompanied by short-circuit current reductions of up to 4% and visible encapsulant browning and interconnect degradation. The combined effects indicate potential cumulative output losses exceeding 20% relative to nameplate ratings. These results emphasize the importance of rigorous stabilization and hotspot qualification testing to ensure long-term reliability, safety, and energy yield of PV modules operating under real-world conditions.