With the continuous improvement of the yield rate of the photovoltaic module market, the quality requirements of solar cells in photovoltaic modules are also increasing with the increase of their yield rate, but the passivation of the surface of solar panels is often deteriorated due to the PID effect, resulting in the attenuation of the module power of the cell

In this issue, we will introduce you how to avoid the PID effect of photovoltaic modules as much as possible!

What is the PID effect?

PID effect, also known as potential-induced attenuation phenomenon, when the module is in a negative bias state, under the influence of external factors, there will be leakage current between the solar cell and the metal grounding point (generally through the aluminum frame), and the packaging material EVA film, backplane, glass, and aluminum frame are easy to become leakage current channels, at this time, the sodium ions in the glass will migrate, and gather on the surface of the solar cell through the packaging material, forming a reverse electric field, resulting in local solar cell failure, resulting in a large attenuation of the module power. This phenomenon is known as the PID effect.

How to avoid the PID effect?

The activity degree of PID is related to many factors, among which the PID effect includes the humidity of the photovoltaic module, the conductivity, acidity and alkalinity of the module surface and the accumulation of pollutants containing metal ions.

● By improving the insulation performance of EVA film, EVA film with high body resistivity is currently mainly used as the encapsulation material, or POE with higher resistivity is used as the encapsulation material, so as to suppress the PID effect with better performance.

● The PID effect can also be avoided by changing the film thickness and refractive index of the ITO film prepared by PECVD.

● In practical application and research, the negative bias voltage of the module is relatively high when it is close to the negative electrode of the inverter, and the PID effect will be more obvious; However, if the negative output end of the component array is grounded, the PID effect can be effectively suppressed.

● Quartz glass without sodium ions can also be used to replace soda-lime glass, so as to inhibit the PID effect, but because this is very difficult in the process, and the cost of quartz glass is relatively expensive, it is not practical to apply it in large quantities in industrial production.