The Importance and Methods of PID Testing for Flexible Solar Panels

Flexible solar panels are lightweight and versatile, making them particularly useful for portable or curved applications, such as boats, RVs, cabins or tents. However, flexible solar panels also face some challenges that can affect their performance and lifespan, such as potential induced degradation (PID).

PID is a phenomenon that causes the photovoltaic (PV) performance of solar panels to degrade over time due to the presence of voltage bias between the circuit and the metal frame. PID can result in reduced power output, lower efficiency, increased leakage current and hot spots1.

PID testing is a method to evaluate the PID resistance of solar panels under high voltage, high temperature and high humidity conditions. PID testing is important for flexible solar panels because it can ensure their long-term stability and reliability, as well as prevent power loss and performance degradation.

PID testing is also required by some international standards, such as IEC 61215-1:20212, which specifies the design qualification requirements for terrestrial PV modules suitable for long-term operation in outdoor climates. According to this standard, PID testing is one of the test methods for design confirmation and type approval of all flat plate module materials.

PID Testing Standards and Techniques

There are different standards and methods for PID testing of flexible solar panels, depending on the module type, technology and application. Some of the common standards and methods are:

l  IEC TS 62804-1:20153, which specifies the test procedure for PID susceptibility of crystalline silicon PV modules.

l  IEC TS 62804-2:2019, which specifies the test procedure for PID susceptibility of thin-film PV modules.

l  IEC TS 63126:2018, which specifies the test procedure for PID susceptibility of PV modules operating at elevated temperatures above 70°C.

l  IEC TS 62941:2016, which specifies the quality system requirements for PV module manufacturing.

The general steps of PID testing are:

l  Place the solar panel in a climate chamber with high temperature and humidity conditions, such as 60°C and 85% RH.

l  Apply a negative voltage bias to the internal circuit and the frame of the panel, such as 1000V.

l  Maintain the voltage bias for a certain period of time, such as 96 hours.

l  Measure the output power and other parameters of the panel, such as EL images.

l  Compare the power degradation rate before and after the test, such as less than 5%.

Conclusion

Flexible solar panels are a promising technology for various applications that require portability or flexibility. However, they also need to withstand harsh environmental conditions that can cause PID effects. PID testing is a vital method to assess the PID resistance of flexible solar panels and ensure their quality and durability. PID testing is also mandated by some international standards that specify the design qualification requirements for terrestrial PV modules.