Comparative Study of the Electrical Parameters of Individual Solar Cells in a c-Si Module Extracted Using Indoor and Outdoor Electroluminescence Imaging

In this article, electroluminescence (EL) imaging is applied to characterize monocrystalline silicon photovoltaic (PV) modules under indoor and outdoor conditions. EL images of PV modules are analyzed to extract dark saturation current density and series resistance for individual cells within the module. These individual solar cells' parameters together with the terminal voltages of the modules, are used to model the current-voltage (I-V) characteristics of individual cells and the module using the one-diode model of solar cells and LTspice. We have explored the method for both indoor and outdoor EL images and compared the results with indoor I-V measurements under standard test conditions (STC). The electrical parameters of the PV module estimated using this approach for both, indoor and outdoor EL measurements are in good agreement with a relatively small deviation of less than 3% from the reference measurements performed under STC. This method is particularly useful to extract the electrical parameter and information on module degradation in the field using the EL only, without performing an I-V measurement.