Noncontact Electromagnetic Induction Excited Infrared Thermography for Photovoltaic Cells and Modules Inspection

Defects can affect the generation efficiency and service life of photovoltaic (PV) cells and modules, and even can cause serious damage to grid connected PV power generation station. This paper proposes active electromagnetic induction infrared thermography defect detection methods for PV cells and modules, which have the advantages of noncontact, rapid, full-field, subtle, and quantitative detection. First, the mechanism of infrared radiation after electromagnetic induction of PV cells is described, and a digital EDT system is established. Then, the thermal image sequences of PV cells and modules are obtained under pulse and lock-in modes of excitation. Fast Fourier transform, independent component analysis, and principal component analysis are used to deal with the thermal image sequences. Finally, the visual detection of defects, including scratches, hot spots, microcracks, surface impurities, and broken grids in PV cells and modules are realized. The experimental results have shown that the proposed method can distinguish the background noise and the defects very well, thus providing a reliable and rapid inspection means for the research, testing, manufacturing, service, and maintenance of PV cells and modules.