Reconstruction and Calibration of Contactless Electroluminescence Images From Laser Line Scanning of Photovoltaic Modules

This article presents image processing methods for reconstructing and calibrating contactless electroluminescence (EL) images acquired with laser line scanning for diagnostic of photovoltaic modules. The method specifically focuses on two outputs: a contactless conventional EL that is calibrated to correspond to electrically biased EL and a contactless highlighted EL that emphasizes visualization of defects. Results are evaluated first by visual inspection, showing similar resolution to electrically biased EL at 2% or 5% Isc. A quantitative analysis by peak signal to noise ratio (PSNR) measures also assesses the resemblance between the reconstructed contactless conventional EL and the reference electrically biased EL.