Potential induced degradation (PID) can lead to a great attenuation in crystalline silicon solar cells module′s power and bring limitation on the large-scale application of solar cells module. The power attenuation problem of module made of different plasma enhanced chemical vapor deposition (PECVD) coating processed polycrystalline silicon solar cells is analyzed experimentally. The results show that compared with the module of standard process polycrystalline silicon solar cells (the refractive index is 2.06), the module made of preventing PID processed polycrystalline silicon solar cells (the refractive index is 2.16) suffers a power attenuation of 1.65% only, which is within the attenuation range of 5%, and has certain abilities of resistance to high pressure, high temperature and humid environment. According to the analysis, under the condition of the certain thickness of optical film, making polycrystalline silicon solar cells module with high refractive index SiNx film can better prevent the happening of the PID phenomenon.