PID effect detection method

Hidden crack, hot spot and Photovoltaic PID effect are three important factors affecting the performance of photovoltaic modules. Today, manufacturers take you to understand the formation of PID effect, detection methods and countermeasures.

1. What is the PID?

PID is the abbreviation for Potential Induced Degradation, refers to the Potential Induced Degradation of components. PID module is the battery module under the action of high voltage for a long time, so that there is leakage current between glass and packaging materials, and a large number of charges gather on the surface of the battery, making the passivation effect of the battery surface worse, easy to make the photogenerated carrier compound, resulting in the performance of the component is lower than the design standard. When the PID phenomenon is serious, it will cause a component power attenuation of more than 50%, thus affecting the power output of the whole group of strings. PID phenomenon is most likely to occur in coastal areas with high temperature, humidity and salinity.

Photovoltaic PID

2. PID detection method

PID recovery solution in PV industry has two ways to accelerate aging:

1) cover the glass surface of the components with aluminum foil, copper foil or wet cloth at a specific temperature and humidity, and apply voltage between the output end of the components and the surface cover for a certain time.

2) apply -1000v direct current to the output end of the component and the aluminum frame for 96 hours at 85% humidity 85℃ or 60℃ or 85℃.

Power, wet-leakage, and EL imaging of the components were performed before either method was tested. After aging, power and wet leakage tests were performed again and EL imaging was performed. The results before and after the test are compared, so as to get the PID under the set conditions. The first method is more widely used in experimental institutions, while the second method is more widely used in photovoltaic module factories. When the PID phenomenon occurs, part of the battery can be seen to be black from EL imaging.

The judgment is based on:

(1) relative to the initial value, the attenuation shall not exceed 5%.

(2) no visual unqualified phenomenon, according to chapter 7 of IEC61215, chapter 10.1.3 of iec61730-2.

(3) the wet leakage current test conforms to chapter 10.15 of IEC61215.

(4) after the test, the components have complete functions.