Analysis of Hot Spot Fault Characteristics in Photovoltaic Modules Based on I-V Output Characteristics and Model Parameters
Early-stage hot spots in photovoltaic (PV) modules, defined as power loss below 25%, represent a critical reliability challenge. This study investigates the evolutionary mechanisms of three distinct hot spot types: shading-induced, crystal defect-induced, and microcrack-induced. An equivalent circuit model was established, and I-V characteristic data were acquired from 104 early-stage hot spot modules (198 total datasets) under irradiance above 800 W/m². Key I-V curve features—short-circuit slope (ksc), open-circuit slope (koc), and cutoff current (Icutoff)—along with model parameters (photogenerated current, series resistance, shunt resistance) were computed. Results reveal statistically significant differences in parameter variation patterns among the three hot spot types. For shading-type hot spots, |ksc| increased by 402.6% to 736.8% relative to normal modules, while |koc| decreased by 1.9% to 20.9%. Crystal defect-type hot spots exhibited |ksc| increases of 1044.7% to 2884.2% and |koc| reductions of 4.2% to 20.1%. Microcrack-type hot spots showed |ksc| increases of 873.7% to 1852.6% and |koc| decreases of 27.6% to 44.2%. The cutoff current declined from 7.61 A to 6.57 A for shading, 7.43 A to 7.09 A for crystal defects, and 7.86 A to 7.52 A for microcracks. These distinct signatures enable preliminary classification of the three hot spot types and differentiation between microcracks and microcrack-induced hot spots, providing a diagnostic basis for targeted maintenance and risk assessment in PV power plants.