Photovoltaic modules are the most important equipment in photovoltaic power generation. In the daily installation and maintenance process, special circumstances can cause thermal spot effect and potential induced decay effect (PID) of photovoltaic modules, causing losses to the majority of owners. Therefore, we should pay attention to controlling the photovoltaic power station during installation and daily maintenance to avoid these two effects.

1、 Thermal spot effect affecting photovoltaic modules

The shaded solar cell modules in a series of branches will be used as loads to consume the energy generated by other illuminated solar cell modules. The shaded solar cell modules will generate heat at this time, which is known as the hot spot effect.

This effect can seriously damage solar cells. Part of the energy generated by illuminated solar cells may be consumed by shaded cells. And the cause of the hot spot effect may only be a piece of bird droppings.

In order to prevent solar cells from being damaged due to the hot spot effect, it is best to parallel a bypass diode between the positive and negative poles of the solar cell module to avoid the energy generated by the illuminated module being consumed by the shielded module. When the hot spot effect is severe, the bypass diode may be broken down, causing the component to burn out, as shown in the following figure:

2、 PID effect affecting photovoltaic modules

The potential induced decay effect is caused by the leakage current between the glass and packaging materials of battery components under high voltage for a long time, resulting in a large amount of charge sniping on the surface of the battery cell, which deteriorates the passivation effect of the battery surface and leads to component performance lower than the design standards. When the PID phenomenon is severe, it can cause a component power attenuation of more than 50%, thereby affecting the power output of the entire string. Coastal areas with high temperature, high humidity, and high salinity are most prone to PID phenomenon.