3201 SMA — DC Overvoltage
At a glance
- Severity
- FAULT STOP
- Domain
- DC_SIDE
- Reference standard
- IEC 62548 / EN 50549-1
- Product / context
- DC Overvoltage
What it means
The open-circuit voltage (Voc) of the DC string exceeds the maximum input voltage of the inverter. The inverter shuts down to protect internal components (capacitors, IGBTs). This typically occurs in early morning hours during winter with low ambient temperatures.
Probable causes
- Excessive number of modules in series in the string relative to the inverter Vmax.
- Design error: Voc not calculated at the minimum site temperature (-10 degrees C or -20 degrees C).
- Modules with actual Voc higher than nameplate data (positive tolerance).
- Replacement of modules with others having higher Voc without recalculating the string.
Reference values
| string sizing | {"limit":"string Voc ≤ inverter max voltage (e.g. 1000/1100 V)","cold_Voc":"at -10 °C silicon Voc rises ~3% vs STC"} |
|---|
Where to start
Measure the Voc of each string with a DC multimeter (inverter off, DC disconnector open). Is the measured value higher than the Vmax indicated on the inverter datasheet?
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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