Influence of Irradiance and Drone Altitude in Infrared Thermography Inspections of Photovoltaic Plants

This study evaluates the effectiveness of drone-based infrared thermography (IRT) for detecting photovoltaic (PV) module defects under varying drone altitudes and irradiance levels. Several PV modules were artificially degraded to induce common faults, including cell cracks, cell interconnect disconnections and short-circuited bypass diodes. IRT images were acquired under irradiances ranging from 200 W/m² to 1000 W/m² and at four different drone altitudes (8 m, 10 m, 14 m, and 20 m). A detailed temperature pattern analysis at both the module and cell level was performed to characterize the thermal signatures of each fault type under the different imaging conditions. Results show that modules with cell cracks are difficult to distinguish from healthy modules while disconnected interconnects display distinct elongated thermal patterns that remain detectable at a minimum irradiance of 600 W/m² and are robust to detect even at higher imaging altitudes. Modules with short-circuited bypass diodes caused prominent hotspots of around 80°C which remained clearly detectable even at low irradiance levels (200 W/m²) and elevated drone altitudes. To support further research, the complete IRT image dataset generated in this study will be made publicly available.