Warning What does this mean?
Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.
SolarEdge Inverter 18XA6 Hardware Fault — What It Means for You
Error 18xA6 is an internal hardware fault on single-phase SolarEdge inverters — on the LCD of older firmware it appears as codes 166–168. SolarEdge's documentation describes it as a DC-link capacitor overvoltage ('Tz Over voltage'), a problem deep inside the inverter's power electronics. The official remedy is to contact SolarEdge support: no setting or reset available to you can repair it.
What should I do first?
Two quick questions — we'll point you to the right starting point.
Is this code still showing on your inverter's display?
Is your system producing power right now?
What this code means
To understand 18xA6, picture what an inverter does thousands of times per second: it switches high-power transistors to sculpt the DC from your panels into grid-synchronized AC. Between the panel side and the switching stage sits a bank of large capacitors — the DC link — which smooths the power flow. 'Tz Over voltage cap' means the inverter's monitoring measured a dangerous overvoltage on those capacitors (on one of three internal measurement channels, hence 18xA6, 18xA7 and 18xA8) and shut everything down to protect the hardware.
Across SolarEdge's documentation generations this fault is consistently treated as a hardware-class problem: newer guides name the capacitor overvoltage explicitly, while others group codes 166–168 / 18xA6–A8 under 'HW error.' Either way, the prescribed action is identical — contact SolarEdge support — because the fault is inside sealed power electronics that only qualified service personnel may touch.
What does this mean for you practically? Your system will not produce until the fault is resolved, and the resolution is a service case, not a DIY project. The most common real-world outcomes are a remote diagnosis by SolarEdge support, an on-site inspection by your installer, or — if the hardware is confirmed faulty — a warranty replacement of the inverter. Repeated power cycling in the hope it 'clears' is the one thing guaranteed not to help a hardware fault.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – kWh of lost production per day.
Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.
Common causes
- ["Grid voltage surges or sustained overvoltage stressing the inverter's internal DC bus beyond what the capacitors and switching stage can tolerate.", 'A degrading internal capacitor or power-stage component that can no longer ride through conditions it once handled.', "A severe grid event — a nearby lightning strike, network switching, or a large load change — that drove a transient the inverter couldn't absorb.", 'In rare cases, a firmware issue misreporting the capacitor voltage — something SolarEdge support can check remotely before concluding the hardware is at fault.']
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 1 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.
When to call an electrician
Error 18xA6 needs a professional from the moment it appears — and definitely once it survives a power cycle. Call your installer or SolarEdge support immediately; this is a manufacturer-level service case, not a maintenance task. Internal hardware faults are normally covered by SolarEdge's 12-year standard inverter warranty (extendable to 20 or 25 years), and your installer typically manages the claim, which frequently ends with a replacement unit being shipped. If the inverter shows any sign of heat, smell, or noise damage, keep people and flammables away from it and say so explicitly when you call.
Frequently asked questions
Can a firmware update fix error 18xA6?
Occasionally. If SolarEdge support's remote diagnosis suggests the overvoltage reading is a measurement or firmware issue rather than genuine hardware stress, they may resolve it with a firmware action. But when the capacitors or power stage are truly degraded, no software can repair them — expect a hardware service outcome.
Will I need a whole new inverter?
Possibly. Internal power-electronics faults often end in a warranty replacement rather than a component repair, because the power stage is not field-serviceable. The good news is that this is exactly what the long SolarEdge warranty exists for — your installer handles the replacement process.
Is error 18xA6 dangerous?
The inverter protected itself by shutting down, so the fault as displayed is contained. The underlying overvoltage is a sign of real electrical stress, though, which is why you shouldn't keep restarting the unit 'to see if it clears' and should get the service case opened promptly.
What is the difference between 18xA6, 18xA7 and 18xA8?
They are the same fault detected on different internal measurement channels (cap 1, 2 and 3). The meaning, severity, and remedy are identical for all three — contact SolarEdge support.
Need a professional?
This fault may need professional diagnosis. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — SolarEdge 'EV Charging Single Phase Inverter Installation Guide' MAN-01-00404-1.1, Appendix A: Errors and Troubleshooting — codes 166-168 (CPU v3.19xx: 18xA6-A8) = 'Tz Over voltage cap1/2/3' (troubleshooting includes verifying country setting, AC grid voltage, wire gauge, grid operator consultation); also classified 'HW error' in SolarEdge 'Single Phase Inverter with HD-Wave Technology Installation Guide' MAN-01-00306-1.1, Appendix A. Listed remedy in all cases: 'Contact SolarEdge support.'