1002 on a Sigenergy SigenStor: Low insulation resistance. Official suggestion (summarised): Check DC cables for shorts/breaks and poles shorted to ground; if only on rainy days re-check when dry; check ISO impedance protection setting in app meets local rules
Short answer
On a Sigenergy inverter, 1002 means: Low insulation resistance. Official suggestion (summarised): Check DC cables for shorts/breaks and poles shorted to ground; if only on rainy days re-check when dry; check ISO impedance protection setting in app meets local rules. The inverter stops until the fault clears or is reset. An engineer is needed to fix the cause.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Low insulation resistance. Official suggestion (summarised): Check DC cables for shorts/breaks and poles shorted to ground; if only on rainy days re-check when dry; check ISO impedance protection setting in app meets local rules.
Likely causes:
- PV string short-circuited to PE, or PV string in chronically humid environment.
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: yes (when insulation recovers).
Manual reset: n/a.
What you can check
- Read the alarm code, name and ID in the mySigen app.
- Report it via mySigen app Support > Troubleshooting (Sigenergy's stated route) or contact your installer.
- If it only appears in wet weather, note the dates and tell the installer.
What the engineer will check
- Insulation-resistance test of each string.
- Inspect DC cabling/connectors.
- Check ISO protection value in installer app.
- Sub-IDs: ID1.
Who to ask for: battery storage / PV inverter.
Certification: Sigenergy-trained installer; MCS PV/battery installer for certified installs; electrical work to BS 7671.
What you might notice
Sources
- Sigenergy Alarm List (Version 05) ↗ · 05 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026