Research On Infrared Image Of Defects In Crystalline Silicon Solar Modules

Solar module’s local defect seriously affects its performance. At present, the main testingmeans have I-V characteristics detection, spectral response testing and visual appearance,which not directly found defect position and causes. For fast accurate diagnosis of solarmodules, the paper researches on infrared image of silicon solar modules’ defects.First, through the research of module infrared image imaging mechanism determined theinfluence factors of electroluminescent. EL principle is the physical mechanism of infraredimaging, and its intensity affects the judgment of solar module defects’ types and location.The length of minority carriers, positive bias and temperature are EL influence factors.Second, analyze the relationship of the infrared images’ light and dark and performanceparameters. According to I-V test parameters, this paper summarizes that short-circuit currentdifference should be less than0.35A, conversion efficiency difference should be less than0.75%, and more than the rating shows that whole string of generating capacity will be low.Third, analyze solar modules’ infrared image of various defects. Classify different image,and to analysis of the output characteristics influence of various defects.Fourth, process defects of infrared image. By the use of the median filtering effectivelyremove the background noise, and keep the features of defects image. Image segmentationuses canny operator with on edge detection, with bwperim function track the target imageedges, extracting the shape characteristic of the defect. Pattern recognition through thecalculation of the hidden crack circle skillfully area, according to the circular degree formulacan be judge whether is implicit crack defects.The study shows that the short-circuit current and conversion efficiency is the mainreason of influence infrared image’ light and dark. According to various defects of imagefeatures, induces three categories of defects, and output characteristics influence, to make theenterprise internal testing standards provide reference basis. Through the image processing,determine the judgement basis of the hidden crack, help to fast accurate diagnosis of defectstypes and positions, and in improving the production efficiency and ensure quality.