## 1 Introduction  
Photovoltaic cells and modules are the core parts of the solar power generation system, and the defects such as fragments, broken grids and hidden cracks are prone to occur in the process of production, transportation, or application; these not only cause production waste but also reduce the power generation efficiency, and may even lead to major safety accidents if excessive temperature caused by equipment damage exists inside the panel. Therefore, it is of very important application value and practical significance to study real-time and efficient defect detection methods for photovoltaic cells and modules. In 2005, [PERSON] et al. captured the light emission of solar cells under positive bias voltage using a short-wave infrared (SWIR) CCD, and found that there is a one-to-one relationship between the emission intensity and the diffusion length of minority carriers. Then, [PERSON] et al. proposed a semi-quantitative analysis method for detecting the diffusion length distribution, diffusion length mapping and degraded areas of minority carriers in silicon-based solar cells with electroluminescence (EL) [1]. In 2007, [PERSON] et al. realized the rapid detection of EL intensity distribution and defects in the region captured by silicon CCD camera within 1 s; they did so by analyzing the impact of the inherent material characteristics, such as diffusion length, recombination velocity at surface and subsurface, and external defects, such as wafer damage and electrode breakdown, on minority carriers. [2]. Based on the above work, the detailed information inside the solar panel, such as minority carrier lifetime, two-dimensional electrical characteristics, series resistance and shunt resistance, has been obtained through electroluminescence, and a defect testing method for crystalline silicon photovoltaic modules based on electroluminescence was proposed [3]. However, the images obtained by traditional electroluminescence detection methods mainly reflect the intensity of shortwave infrared radiation generated by carrier recombination, and the impact of radiation emitted from optical and physical properties, edge characteristics, texture and other aspects of the defect area has not been taken into account, which makes it difficult to quantify the defect area and give accurate judgments on the type and impact of the defects. Excited by external positive bias voltage, photovoltaic cells usually emit short wave infrared light with a peak wavelength of about 1150 nm which has polarization characteristics [4]. Polarization is the fourth piece of important information in addition to basic attribute strength, wavelength, and phase of electromagnetic waves. Through polarization imaging, not only the intensity but also the physical characteristics, geometric information and surface texture characteristics of the target can be obtained or resolved. In 2002, [PERSON] et al. found that solar panels are the main source of the polarization characteristics of satellite surface scattering when predicting the polarization characteristics of satellites in different Earth orbit scenarios, using the advanced tracking time domain analysis simulation system (TASAT) to generate polarization renderings of satellite models [5]. In 2010, [PERSON] et al. found that the polarization characteristics of the scattered light on the surface of the solar panel are related to the composition materials; the angle of incidence and the attitude have a large impact, where the amount of polarization can be used to improve the recognition ability of space targets [6]. [PERSON] et al.