2051 on a Huawei SUN2000-L1 single-phase hybrid-ready inverter: Input-side insulation impedance to PE decreases during operation (Major)
Short answer
On a Huawei inverter, 2051 means: Input-side insulation impedance to PE decreases during operation (Major). The inverter stops until the fault clears or is reset.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Input-side insulation impedance to PE decreases during operation (Major).
Part involved: residual current.
Likely causes:
- Insulation fault on PV side.
Is it safe?
Switch the inverter off at its isolator and call an engineer.
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
The inverter stops until the fault clears or is reset.
Resetting itself: yes.
Manual reset: Recovers automatically after fault rectified.
What you can check
- Read the full code and message on the inverter screen or in the FusionSolar app and note the date/time for your installer.
- Check the inverter's AC isolator next to the inverter and the solar/battery breaker in the consumer unit are ON (do not reset a breaker that trips again - call your installer).
What the engineer will check
- Check PV string-to-ground impedance.
Who to ask for: MCS-certified solar PV installer (DC/string work) or the original installer.
Certification: Work on DC strings and inverter enclosures: competent PV installer (MCS-certified installer for warranty/SEG continuity); electrical work notifiable under Part P (England & Wales) or equivalent.
What you might notice
Sources
- SUN2000-(2KTL-6KTL)-L1 User Manual (Copy, AU) ↗ · Issue 06 · page PDF p.92 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026