Daylight Electroluminescence Imaging Methodology Comparison

Electroluminescence imaging is a powerful technique for PV fault diagnosis and for this reason there is a growing interest of the O&M industry to make it widely available for in site inspections instead of randomly choosing samples throughout the PV plant. Few groups in the world disclose methodologies for daylight EL (dEL) image acquisition of installed PV modules, using different equipment and image processing procedures. In this work, we aim to compare methodologies from two research groups that have been working on practical ways to perform robust dEL imaging in parallel. We present the results from acquisitions made with similar but not identical equipment, weather conditions and PV module technologies. Image processing on the same datasets from both laboratories is performed using their own methods, indicating if the image processing methods and approach provide consistent results or not. While each laboratory has developed its own signal-to-noise ratio markers, both present good consistency with signal at an exposure time analysis, but not always a direct correspondence to the image quality. This intercomparison will lead to improvements on each laboratory procedure, expand the discussion to other groups and initiate a discussion on the establishment of dEL image quality and SNR metric baselines.