Quantitative Estimation of Shunt Resistance in Crystalline Silicon Photovoltaic Modules by Electroluminescence Imaging

Ohmic shunts in crystalline silicon (c-Si) solar cells and modules are of critical concern as these affect the open-circuit voltage, fill factor, and the net output power. In modules, such shunts create a mismatch and can lead to hotspot formation that can thermally destroy the module. It is essential to estimate the shunt resistance value in a nondestructive manner in order to prioritize the removal of shunts on the basis of severity. In this paper, an approach to estimate the quantitative shunt resistance values in crystalline silicon photovoltaic (PV) modules by electroluminescence (EL) imaging has been presented. The quantitative properties of EL emission from the solar cell has been correlated with shunt resistive effects, which has led to the estimation of the voltage and current across the shunts, and hence the shunt resistance values. The approach has been experimentally supported by externally introducing shunt resistances of different values in a solar cell. The estimated shunt resistances have been found to be in a good agreement with the actual shunt values. This work can be helpful in detailed quantitative analysis of ohmic shunts, which can be further used to improve the performance and reliability of PV modules.