Figure 8 : Positive voltage shift during night (Source: Research Gate)

System level: As we had mentioned above on the system level, PID can be avoided by using transformer PV inverter. However, if we use transformer-less inverter various options are available in the market such as PV offset box by SMA, Zigzag-connected Chopper Converter by Omron, etc. When after sunset if the array voltage drops below a threshold value, the offset box raises the voltage of the entire string (to a higher positive value (as shown in Figure 8 ) with respect to earth). This reverses the polarization effect which had occurred in the module (and the string) during operation.
Cell and Module level: We can avoid PID (partly or fully) by changing the raw materials we use. For glass, we could use glass with low sodium content. One option in consideration is to shift to quartz based glass instead of soda lime glass. In encapsulant, we could shift from EVA to Poly Olefin Elastomer (POE), an encapsulant believed to reduce and even limit PID. For cells, the thickness of ARC and the ratio of Si:N can be closely monitored. Additionally, homogenous deposition of ARC on solar cell can ensure that the solar cell is PID free.
Environment factors: The best and the only option available so far for environmental based factors is to get the modules tested as per the testing standards. International Electrotechnical Commission (or more commonly IEC) has come up with a testing certificate IEC TS 62804-1. This test prescribes the modules to be tested at elevated temperature (at 85 °C) and Relative Humidity of above 85% for 96 hours in a special chamber. The module’s performance is then tested to check the effect of stresses inducedin the module.

Waaree uses standard materials which are certified to be PID free. Additionally, our modules are certified by the IEC agency to be PID free. Also, we do extended testing above the specified test standard to ensure the reliability of our product under extreme climatic conditions. The reader can view all the certifications we have here.

Let us all pledge to make solar energy the primary source of energy in the near future.

RAHE ROSHAN HUMARA NATION