18x3B on a SolarEdge HD-Wave single-phase inverter: I-ACDC: AC overcurrent (I-ACDC L1/L2/L3); if flagged on all three phases at once, most likely a DC-related issue on site
Short answer
On a SolarEdge inverter, 18x3B means: I-ACDC: AC overcurrent (I-ACDC L1/L2/L3); if flagged on all three phases at once, most likely a DC-related issue on site. 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: I-ACDC: AC overcurrent (I-ACDC L1/L2/L3); if flagged on all three phases at once, most likely a DC-related issue on site.
Part involved: Inverter internal hardware / firmware.
Likely causes:
- DC string issue (improper installation/stringing).
- Inverter fault.
Is it safe?
| Does the inverter stop? | Yes |
|---|---|
| Severity | Fault — needs a manual reset once the cause is fixed |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: sometimes clears after a restart; recurring = hardware fault.
Manual reset: restart; otherwise replacement.
What you can check
- Read and note the exact code and time from the inverter display or app (screenshot).
- Check the solar/battery AC isolator and the consumer-unit breaker/RCD are ON (do not reset a breaker that trips again immediately).
- If the code persists, contact the installer. SolarEdge's list says 'OFF/ON to reconnect' for some codes - that means the inverter's own ON/OFF switch; only use it if your installer has shown you how. Never open the inverter or touch DC cables/connectors.
What the engineer will check
- Restart per manual.
- Update firmware.
- Contact manufacturer support with serial number; RMA if repeated.
Who to ask for: PV installer with manufacturer support access.
Certification: Electrician competent in grid-connected PV (BS 7671 Section 712; IET Code of Practice for Grid-connected Solar PV), ideally the original MCS-certified PV installer; brand-approved/trained installer to keep manufacturer warranty.
What you might notice
Sources
- User Guide: SolarEdge Inverters Error Codes and Troubleshooting, Version 1.1 (January 2026) ↗ · 1.1 · page PDF p.20 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026