PID Recovery Guide for Solar Installers

What is PID?

Potential-induced degradation (PID) is a gradual power loss in crystalline silicon modules caused by high voltage stress between the cell and the module frame. In systems where the negative string terminal is not grounded — common in transformer-less inverter setups — leakage current flows through the module glass and frame, degrading the cell’s surface passivation layer.

Identifying PID

Signs of PID include:

• String output significantly below PVSyst prediction despite clean modules
• Electroluminescence imaging revealing dark cell edges or uniform dimming across affected modules
• Gradual loss that started after the first summer and worsens year-on-year

PID is more common in hot, humid climates (Greece, coastal Netherlands) and in high-voltage string designs.

Stopping PID progression

1. Check inverter grounding. Enable the PID compensation function if your inverter supports it (Sungrow SH-RT and GoodWe ET Plus both include this).
2. Reduce string voltage at high-temperature hours if the design allows.
3. Apply anti-PID boxes to legacy string inverter installations without built-in compensation.

Recovery

PID damage in its early stages is reversible. Overnight, the inverter’s PID compensation circuit applies a small positive bias that allows the module’s surface passivation to partially recover. Full recovery can take 2–6 weeks of overnight treatment. Modules with more than ~15% power loss are unlikely to fully recover but typically stabilize.

Prevention

Specify N-type TOPCon modules (like the Jinko Tiger Neo) for new installations — they are structurally immune to PID. For existing PERC fleets, ensure inverter PID compensation is enabled and log the correction current monthly.