Suspected PID
A thermal pattern consistent with early potential induced degradation, but not yet definitive. Kept as a separate class so a suspected case can be verified before committing to PID mitigation.
This class is part of the taxonomy our reports are written in, but our analysis does not currently flag it. The page is field reference for your own review. The eight classes we do flag today, and how well, are on the validation page.
Thermal signature
A faint patchwork of slightly warmer cells on scattered modules — the PID checkerboard, but weak, incomplete or without a clear string-position gradient. The signature is subtle enough that soiling patterns, module batch differences or capture conditions could plausibly explain it.
Typical ΔT
2–6 °C on scattered cells (typical industry interpretation aligned with IEC TS 62446-3). At this level, pattern and repeatability across inspections carry more weight than the raw ΔT.
What causes it
- Early-stage PID before the string-position gradient becomes obvious
- Mixed module batches with slightly different thermal behaviour
- Light, evenly distributed soiling mimicking a cell-level pattern
- Marginal capture conditions reducing the signature's clarity
Power impact
If it is PID, losses are still small — typically a few percent — but they compound while the voltage stress persists. The cost of confirming early is a fraction of the cost of remediating a site-wide PID problem discovered late.
Recommended action
Fix: next maintenance window
Verify at the next maintenance window: electroluminescence-test a sample of the flagged modules (prioritising negative-end string positions), compare against the previous inspection, and re-fly or re-inspect in the next cycle to see whether the pattern intensifies.
Frequently asked questions
Why flag 'suspected' PID instead of waiting for certainty?
Because PID is progressive and cheap to confirm early. An EL test on a handful of modules settles the question; waiting for the thermal signature to become unmistakable means accepting another year of compounding, partially irreversible degradation across the site.
What single check best separates PID from lookalikes?
String position. True PID intensifies toward one end of each string because the cell-to-ground voltage is largest there. If the flagged modules show no positional pattern, soiling or batch variation becomes the more likely explanation.
Related anomalies
Planning a thermal inspection?
This class (Suspected PID) is not flagged by our analysis today; the page is field reference for your own review. The eight classes we do flag, with their measured performance, are on the validation page. Quote your site size in seconds.
ΔT figures and abnormality classes on this page describe the typical industry interpretation aligned with IEC TS 62446-3 — indicative engineering guidance, not normative text from the specification. Temperature differentials are only meaningful when captured at ≥600 W/m² irradiance (per the TS) and verified on site before repair work.