PID does not have a single root cause and can affect any crystalline-silicon or thin-film module, regardless of age, manufacture, operating conditions, or installation. However, factors known to increase the likelihood of PID include hot and humid operating environments, improper grounding of the module frames or inverters, and damage from impact events or module mishandling during shipping or installation. Thus the threat of PID is yet an additional reason for EPCs and owners to pay close attention to these installation quality details even if it means extra upfront construction costs.
Similarly, there is no foolproof method to prevent PID. Some system operators have reported good results in mitigating its effects with “float controllers” or “anti-PID boxes.” These devices work by creating a connection overnight between a PV string’s negative electrode and ground in parallel with the inverter, thus allowing the differences in electric potential to dissipate. While these technologies may hold promise in the future; they are still relatively novel and lack a proven track record. They also increase installation complexity and cost, consume power to operate, are a potential point of failure, and are not necessarily compatible with all inverters or system configurations. Therefore, they do not yet eliminate the need for owners and O&M contractors to develop a preventative maintenance plan to detect and mitigate PID throughout a system’s operational lifespan.
