Potential-Induced Degradation (PID)
Potential-Induced Degradation (PID) is a phenomenon that can affect the performance of solar panels over time. It occurs when an undesired voltage potential is created between the photovoltaic (PV) cells and other conductive elements in the solar panel system.
PID typically occurs in photovoltaic systems that have certain conditions present, such as high system voltages, high humidity, and high temperatures. The main contributing factors to PID are:
Leakage currents: When the PV system is exposed to moisture or humidity, electrical currents can leak between the conductive elements, including the PV cells, frame, and grounding components. These leakage currents can lead to voltage differences and cause PID.
Electric field: Under normal operating conditions, the PV cells have a certain electric field distribution. However, in the presence of an external potential, the electric field within the cells can be altered, affecting their performance.
The combination of these factors can lead to a phenomenon where the power output of the solar panel decreases over time, sometimes significantly. PID can cause power losses ranging from a few percentage points to even 50% or more, depending on the severity of the condition.
To mitigate the effects of PID, various measures can be taken:
Anti-PID solar panels: Manufacturers have developed solar panels with improved resistance to potential-induced degradation. These panels incorporate specific design modifications and materials to minimize the effects of PID.
System grounding: Proper grounding techniques can help reduce the potential difference between the various conductive elements in the PV system, minimizing the occurrence of PID.
PID recovery devices: Devices such as PID recovery boxes or PID recovery systems can help mitigate the effects of PID by applying a reverse bias voltage or conducting specialized treatments to the affected panels.
It's worth noting that PID is more commonly observed in older solar panels, particularly those with certain module technologies, such as older crystalline silicon modules. Modern solar panels, especially those with PID-resistant features, are designed to minimize the impact of PID and are less prone to its effects.