3503 SMA — Potential Induced Degradation (PID)
At a glance
- Severity
- WARNING
- Domain
- DC_SIDE
- Reference standard
- IEC 62804-1 / IEC TS 62804-1-1
- Product / context
- Insulation Monitoring - PID
What it means
Progressive module power degradation caused by leakage currents between the cells and the frame, induced by high negative voltage to ground. Can cause yield losses from 10% to 70% over months.
Probable causes
- Floating grounding scheme with the negative pole at high voltage relative to ground.
- Modules not PID-free certified or with low-quality encapsulant (EVA).
- High humidity and temperature environment accelerating leakage currents.
- Absence of anti-PID device (PID box) on systems with transformerless inverters.
Where to start
Compare the measured power of each string in the early morning hours (low irradiance) with the design expected values. Do the strings closest to the negative pole show a drop greater than 10% compared to strings near the positive pole?
Full guided diagnosis in the app
The diagnostic tree for this fault has 7 guided steps with measurements, checks and resolutions. You'll find it in ElectraIQ, one of the five IndexOS apps: free, works offline.
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