Large-Scale Daylight Photoluminescence: Automated Photovoltaic Module Operating Point Detection and Performance Loss Assessment by Quantitative Signal Analysis

Daylight photoluminescence (DPL) is a relatively novel imaging technique utilized in photovoltaic (PV) system inspection, using the sun as excitation source. Filtering the luminescence signal from the strong sun irradiation is its main challenge. Images acquired at two different operating points (OPs) of the module, allow subtraction of the background radiation while maintaining the luminescence signal. A DPL-ready inverter, which is able to toggle between manually selectable OPs of connected PV modules, is presented in this work. Synchronization of image acquisition and OP switching becomes particularly challenging if the camera is applied to unmanned aerial vehicles. To overcome this challenge, an algorithm is developed to identify OP switches in a set of images taken in the field by investigating image intensities. Further, by working out the detailed dependencies of the signal recorded during DPL, the temperature coefficient of photoluminescence intensity is derived theoretically, and its impact on quantitative inspections. The potential field application of DPL images to identify performance loss in PV modules is investigated by two approaches: recording the signal intensity of images over time and comparing the signal intensity of different PV modules in one image. For both approaches, their hypothetical applicability is shown experimentally. Daylight photoluminescence (DPL) is a novel inspection method for large-scale photovoltaic (PV) module inspections. A new inverter development allows direct operating point switching of connected PV modules. An investigation of quantifying the luminescence signal intensity in DPL images shows the possibilities of using this technique for performance loss degradation analysis.image (c) 2023 WILEY-VCH GmbH

Automated summary

Daylight photoluminescence (DPL) is a novel imaging technique used for photovoltaic system inspection. This study presents a DPL-ready inverter that allows switching between different operating points of connected PV modules. An algorithm is developed to identify operating point switches in field images. The research also investigates the quantification of luminescence signal intensity in DPL images and explores its application in performance loss analysis.