The Potential Induced Degradation (PID) can be reversible or irreversible, depending on its origin. Unfortunately, the PID is irreversible when it’s caused by electrochemical reactions, as it induces film delamination in the PV panel or electro-corrosion.
Otherwise, anti PID devices can be used in order to reduce or even eliminate the PID effects. These systems “regenerate” the modules during the night by submitting them to a high positive potential when the array voltage falls below a defined threshold. This reverses the ion migration which occurs during operation in the daytime. The normal performance can be reached again one month after the installation of the anti PID boxes. However, if the panels have been subject to PID for a long time, the regeneration will last half of the degradation period. The power consumption of the anti PID is low since the applied current to reverse the PID effect is low.
For PV projects at the development stage, a way to avoid or at least limit PID occurrence is to use PID resistant modules. These modules are obtained using alternative materials, which show a low degradation rate during rough conditions, test performed by independent laboratories. However, the choice of such modules increases the initial project costs.
PID effects will be eliminated in the long-term if changes are made to the design of the PV systems, modules or cells.
By Clément Vinet, Asset Manager