Power Losses From Series Resistances—Analysed Using Daylight Photoluminescence Imaging

Fast and accurate performance analysis of fielded solar modules is essential for the reliable, long-term operation of large-scale solar farms. Daylight photoluminescence imaging has emerged as a promising inspection method, providing quantitative information while circumventing many logistical constraints associated with alternative methods. Luminescence images of modules acquired with partial current extraction reveal series resistance defects, a key contributor to cell and module degradation. A novel method is presented to estimate the reduction in output power caused by series resistance defects, based purely on daylight photoluminescence image data. This automated process generates electrical models to match series resistance-related intensity variations observed in daylight photoluminescence images, which are used to quantify performance losses. Cell-level simulations and experimental results are presented, yielding excellent results, as well as promising proof-of-concept demonstrations on full modules.