18x8E on a SolarEdge HD-Wave single-phase inverter: Arc Fault Detected: Arc detection / arc fault detected (Arc-DSP)
Short answer
On a SolarEdge inverter, 18x8E means: Arc Fault Detected: Arc detection / arc fault detected (Arc-DSP). 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: Arc Fault Detected: Arc detection / arc fault detected (Arc-DSP).
Part involved: Arc fault detection (AFCI).
Likely causes:
- Series arc on DC side: loose/poorly crimped or mismatched MC4 connector, damaged cable.
Is it safe?
Switch the inverter off at its isolator and call an engineer.
| Does the inverter stop? | Yes |
|---|---|
| Severity | Safety lockout |
| Engineer needed? | Yes |
The inverter stops until the fault clears or is reset.
Resetting itself: no (brand-dependent: some models auto-clear a limited number of times).
Manual reset: yes - after an installer has inspected the DC side.
What you can check
- Read and note the exact code and time from the inverter display or app (screenshot).
- Leave the system off at the AC isolator if you smell burning or see scorching and call the installer.
- Do not reset repeatedly.
- 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
- Inspect every DC connection/MC4 pair, optimiser/connector mismatches, damaged cable.
- Thermal-image the array and DC isolators.
- Follow manufacturer arc-fault application note before clearing.
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.5 · Reviewed 24 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 24 September 2026