The PID effect (Potential Induced Degradation) is a voltage-induced performance degradation in crystalline solar modules. High system voltages (typically 600–1,500 V DC) cause leakage currents through the module glazing, which can lead to performance losses of up to 70%.
When a negative voltage exists between the cell and the frame, sodium ions migrate from the glass into the anti-reflective coating and the cell surface. This causes a shunting effect and reduces the open-circuit voltage. PID is promoted by high humidity, high temperatures, and system voltages above 600 V.
PV-BESS-Assessor employs the following diagnostic methods: Electroluminescence imaging (EL) reveals affected cells as dark areas. IV curve measurements quantify the performance loss. Thermography identifies conspicuous temperature patterns. The combination produces a forensically robust damage profile.
PID is in many cases partially reversible through night-time regeneration (applying a positive voltage overnight) or through specialised PID recovery boxes. However, full recovery is not guaranteed — particularly with long-standing PID, irreversible cell damage may be present. An expert assessment quantifies the regeneration potential.
PID Degradation: 31% Loss at 280 kWp System
Real anonymised investigation case with measurement data, timeline, and economic evaluation.
Last updated: 2026-06-16