Comparison of Line Scan Luminescence Imaging Techniques for Defect Characterisation in Crystalline Silicon Solar Modules

Luminescence inspection of modules is currently being adopted as a standard practice in the photovoltaic industry. This paper presents a comparison of electroluminescence and photoluminescence imaging on industrial crystalline silicon modules, employed with a line scan system. We find that specific defects appear differently in the two techniques due to the difference in excitation method. Line scan photoluminescence images enable differentiation of series resistance defects from recombination defects and can identify the presence of encapsulant discolouration. Line scan electroluminescence images allow defects that prevent majority carrier transport to be evaluated. The use of both techniques enables robust defect characterisation.