Solar · Error codes · AlphaESS
100003AlphaESS · SMILE-G3
100003 on an AlphaESS SMILE-G3: Grid_UFP - grid under-frequency
Short answer
On an AlphaESS inverter, 100003 means: Grid_UFP - grid under-frequency. The inverter stops until the fault clears or is reset.
Reviewed 24 September 2026 · 1 source
What it means
The manual says: Grid_UFP - grid under-frequency.
Likely causes:
- Grid frequency abnormal.
Is it safe?
| 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: Restart of the inverter by installer (power-down/power-up sequence) if it does not clear.
What you can check
- Read the code in the AlphaCloud app/web portal (or the LED pattern on the unit) and note it with the time. Check the inverter's AC isolator and the consumer-unit breaker for the inverter are ON. Report persistent or repeating codes to your installer - AlphaESS says 'call the service' if it does not clear.
What the engineer will check
- Check grid frequency and grid-code settings.
Who to ask for: MCS PV/battery installer familiar with AlphaESS.
Certification: MCS-certified solar PV installer (MIS 3002) or competent electrician (BS 7671 / Part P in England & Wales); DC work only by PV-trained installer.
What you might notice
Sources
- Installation, Operation & Maintenance Manual of SMILE-G3-S3.6/S5/B5 (V01, 14.08.2023) ↗ · V01 · page p.81 (printed) · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026