Exploring the Challenges in the External Quantum Efficiency Measurement of Solar Cells in a PID Affected Module Using PSpice Simulations

Potential Induced Degradation(PID) is an important field degradation mode that can cause warranty claims. Quantum Efficiency (QE) of the cells inside modules degraded by PID needs to be known in order to reduce the uncertainty in the flash I-V measurement of modules. QE measurement of a cell in a PID degraded module can also assist in diagnosing the reasons for the degradation. The cell whose QE needs to be measured must be shaded and maintained at short circuit condition. The load point of the module needs to be calculated to ensure this. The challenges in estimating the load point for PID degraded modules are illustrated through the simulation study. The applicability of the method for finding the load point is tested for degraded, partially degraded and non-degraded cells in the PID affected module. It is explained that the method is valid for non-degraded and partially degraded cells. The cells that are degraded don’t give expected short circuit current due to considerable errors. Hence the QE results won’t be accurate for degraded cells in a PID affected module.