Method for Automatic Calculation of the Exposure Time in Electroluminescence Imaging of Photovoltaic Modules

Electroluminescence (EL) imaging of photovoltaic (PV) modules requires careful selection of the measurement parameters, such as camera sensor exposure time, for obtaining accurate images for qualitative and quantitative evaluation of PV module failures. In this work we propose a method for determining the optimal exposure time for EL imaging of PV panels, with respect to maximizing the utilized camera sensitivity range and limiting image saturation due to overexposure. The method requires two EL measurements of the PV panel, at two distinct exposure times, that are used to calculate the optimal exposure time. The main advantage of the proposed method over manually calibrating the exposure time of the camera is that it can be integrated in the camera image acquisition application, for automatic exposure time calibration.