Solar · Error codes · GoodWe Technologies Co., Ltd.
vac-failureGoodWe Technologies Co., Ltd. · GoodWe DNS (2.9-6 kW)
vac-failure on a GoodWe Technologies Co., Ltd. GoodWe DNS: Vac Failure
Short answer
On a GoodWe Technologies Co., Ltd. inverter, vac-failure means: Vac Failure. 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: Vac Failure.
Part involved: Vac Failure.
Likely causes:
- Inverter restarts automatically within 5 minutes if grid returns to normal; check grid voltage; check N and PE; contact service.
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.
Manual reset: Automatic when condition clears.
What you can check
- Read the message on the inverter LCD or in the SEMS Portal app and note it for your installer.
- It should restart on its own within 5 minutes once the grid is normal.
- If frequent, tell your installer (possible high local grid voltage).
What the engineer will check
- Measure grid voltage; check N and PE connections; DNO liaison.
Who to ask for: GoodWe-trained PV installer.
Certification: Qualified electrician (BS 7671; MCS-certified PV installer for work on the PV array/DC side).
What you might notice
Sources
- User Manual Grid-Tied PV Inverter DNS Series 2.9-6kW ↗ · V1.3-2026-09-10 · page 38 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026