Electroluminescence as a Tool to Study the Polarization Characteristics and Generation Mechanism in Silicon PV Panels

Electroluminescence is a defect detection method commonly used in photovoltaic industry. However, the current research mainly focuses on qualitative analysis rather quantitative evaluation, since there exists some shortcomings, such as fuzzy edges, unclear texture, etc., in the obtained electroluminescence images. Electroluminescence polarization imagery is a new method for defect detection in photovoltaic modules, which can effectively make up for the aforementioned deficiencies. In this paper, the polarization characteristics and formation mechanism of silicon solar panels was investigated based on the principle of electroluminescence. Firstly, the polarization imaging mechanism of electroluminescence of photovoltaic modules was studied. Then, an electroluminescence polarization experimental platform was built, and the polarized electroluminescence images of photovoltaic panels were obtained and preprocessed with Gaussian filter. Finally, the influence of view angle, bias voltage and other factors on the polarization characteristics was discussed. The results show that the electroluminescence of photovoltaic modules has polarization characteristics, and the degree and angle of polarization are related to the view angle and bias voltage; the degree of polarization of photovoltaic panel electroluminescence increases with the angle of view, and first increases then rapidly decreases with bias voltage.