Photovoltaic modules are the most important equipment in photovoltaic power generation. Special situations in the daily installation and operation and maintenance process will cause the hot spot effect and potential induced attenuation (PID) of photovoltaic modules, causing losses to the majority of owners, so we should pay attention to preventing the photovoltaic power station from confronting these two effects when installing and maintaining the power station.
The shaded solar cell module in a series branch will be used as a load to consume the energy generated by other solar cell modules with light. The shaded solar cell module will generate heat at this time, which is the hot spot effect.
This effect can severely damage solar cells. Part of the energy produced by the solar cell with light may be consumed by the shaded cell. The hot spot effect may only be caused by a piece of bird droppings.
In order to prevent the solar cell from being damaged due to the hot spot effect, it is best to connect a bypass diode in parallel between the positive and negative poles of the solar cells and modules to prevent the energy generated by the module with light from being consumed by the shaded module. When the hot spot effect is severe, the bypass diode may be broken down, causing the module to burn out, as shown in the figure below:
The potential-induced attenuation effect is that under the action of high voltage for a long time, there is leakage current between glass and packaging materials, and a large number of charges accumulate on the surface of the cell, which worsens the passivation effect of the cell surface and leads to the performance of the cell below the design standard. When the PID effect is serious, the power of a module will be attenuated by more than 50%, thereby affecting the power output of the entire series of modules. The PID effect is most prone to occur in coastal areas with high temperature, high humidity, and high salinity.
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