Challenges of Aerial Drone Electroluminescence in Solar Photovoltaic Field Inspections

This work aims to give insight into the challenges of performing aerial daylight drone Electroluminescence (EL) inspections in PV farms. In this context, we have compared an EL inspection process using a tripod to record the images to an aerial drone EL inspection system. We focus on the challenges of the “Stop and Go” procedure for recording EL images with the drone, which consists of stopping the drone module by module during the inspection flight. The drone inspection tests resulted in an average module inspection time of 24 seconds per module and around 8 minutes per PV string. Regarding image processing challenges, drone inspection requires an added module tracking algorithm due to the drone motion which introduces some artifacts in the image but does not lower the image quality and diagnostic information of the images compared to stationary daylight EL. Images acquired with both the drone and tripod fail in identifying microcracks in the images but do well in detecting larger B and C cracks. For obtaining the best possible image quality, it is essential to have a calibrated camera, avoid shadows from the drone when recording, and avoid taking images with fast-changing irradiance.