PID (Potential Induced Degradation) is a phenomenon in which the power of photovoltaic modules is rapidly attenuated due to the high ground potential in high-voltage photovoltaic systems. This phenomenon is related to the scale and polarity of the photovoltaic system. Specifically, the photovoltaic modules are exposed to high voltage for a long time, which causes leakage current between the glass and the packaging materials. A large amount of charge accumulates on the surface of the cell, which deteriorates the passivation effect of the battery surface, resulting in a decrease in the FF, 1V and other indicators of the photovoltaic modules, making the module performance lower than the design standard, and some power attenuation even exceeds 40%. In particular, the popularity of 1000~1500V high-voltage systems in recent years has increased the impact of high-potential PID on photovoltaic modules.
There are currently many factors that cause PID, which can be divided into environmental factors, system factors, module factors and battery factors. At present, the entire industry is still conducting various tests and there are disputes. There is no recognized unified detection standard for the PID phenomenon. The PID phenomenon of the module may be caused by one or more of the above factors.
Environmental factors mainly refer to high humidity and high temperature, which are the two main factors that cause PID phenomenon. Studies have shown that PID is more likely to occur in an environment with high humidity and high temperature, especially when the relative humidity reaches more than 60%.
System factors mainly refer to the grounding system power supply and inverter type, which can greatly affect the difficulty of the system to produce PID.
Component factors mainly refer to the design of the component, the panel glass and backplane used, EVA and other packaging materials, which may also increase the occurrence of PID phenomenon.
Battery factors mainly refer to the anti-reflective coating of the battery cell and the resistivity of the PN junction, which may also be related to the occurrence of PID.
How to avoid PID
Methods to prevent PID attenuation include: using better quality component packaging materials to improve the reliability of EVA film; upgrading the production and manufacturing process of photovoltaic components; grounding the negative pole of the photovoltaic component or applying a forward bias to the photovoltaic component during the design and construction of the photovoltaic power generation system.
