18x7F on a SolarEdge HD-Wave single-phase inverter: IRCDMax: RCD current surge - ground faults may occur due to insufficient insulation to the ground
Short answer
On a SolarEdge inverter, 18x7F means: IRCDMax: RCD current surge - ground faults may occur due to insufficient insulation to the ground. 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: IRCDMax: RCD current surge - ground faults may occur due to insufficient insulation to the ground.
Part involved: Residual current / ground fault monitoring (RCMU).
Likely causes:
- DC insulation fault.
- Earth leakage.
Is it safe?
Switch the inverter off at its isolator if the code comes back.
| 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: may retry; persistent or repeated trips need investigation.
Manual reset: sometimes.
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).
- Do not touch DC cabling or open the inverter; manufacturer says only a qualified technician should handle this.
- 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
- Isolate AC and DC, wait for capacitors to discharge (5 min SolarEdge).
- Reconnect strings one at a time to find the faulty string.
- Insulation-resistance test.
- Check AC neutral/earth connections.
Who to ask for: PV installer.
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
- Troubleshooting SolarEdge Systems, Addendum (Europe & APAC) MAN-01-00333-1.2 ↗ · MAN-01-00333-1.2 · page PDF p.6 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026