Characterization and Analysis of PV Module Defects and Degradation Mechanisms through Use of Module External Quantum Efficiency

This paper proposes a module-level external quantum efficiency (m-EQE) technique to analyze optical losses in photovoltaic (PV) modules caused by common degradation mechanisms and defects. The effectiveness of m-EQE is compared to conventional methods such as illuminated IV and UV-F imaging. Measurements of m-EQE, IV, and UV-F are taken on three different modules, two exposed to a desert climate for seven years and one kept indoors. The analysis shows that the aged modules experience a decline in performance, particularly at lower wavelengths as correlated by m-EQE, which corresponds to the UV-F degradation patterns observed. The m-EQE technique has proven to provide an edge in defects analysis and is an easy-to-use, verifiable, and standardizable method for analyzing module-level optical losses.