Although the efficiency of photovoltaic modules is improving year by year and their service life is as long as 20-25 years, power generation is guaranteed and users' expected returns are very clear.
However, photovoltaic modules operate in extremely harsh environments. Whether in large-scale ground-mounted power plants or in applications such as agricultural-solar hybrid systems or fishery-solar hybrid systems, their efficiency decreases during use, thus affecting power generation. Among these, the PID effect is the "efficiency killer" of the modules.
PID effect is short for Potential Induced Degradation. It occurs because photovoltaic modules, under alternating conditions of moisture and high temperature during use, are difficult to keep sealed for extended periods. This leads to a large accumulation of charge on the surface of the cells inside the module, affecting passivation and ultimately causing a decrease in module efficiency, with power generation potentially dropping by more than half.
Since its discovery in 2005, the PID effect has been a major concern for photovoltaic companies and research institutions. Although its cause is not entirely clear, it is generally believed that the PID effect is more likely to occur in coastal areas with increased humidity and higher salinity.
Through long-term experimentation, the industry has also proposed some methods to prevent PID effects. These mainly include the following three: grounding the negative terminal of the series-connected modules or applying a positive voltage between the modules and ground at night; further improving the lifespan and quality of the EVA film and optimizing the encapsulation process; and modifying the cell emitter and SiN anti-reflection layer.
