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.
GoodWe Inverter Error 15 Vac Failure — Grid Voltage Out of Range
Error 15 on a GoodWe inverter means "Vac Failure": the AC voltage from your electricity grid drifted outside the range your inverter is allowed to operate in, so it disconnected from the grid. In most cases nothing is wrong with the inverter itself — grid voltage fluctuates, and your inverter is legally required to step aside until it settles. It reconnects automatically, usually within minutes, once the voltage is back inside limits.
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
Your inverter is a grid-following device: it may only feed power into the network while the grid's voltage and frequency sit inside strict limits defined by your country's grid code. GoodWe's official XS series user manual defines Error 15 as "Vac Failure": "Grid voltage out of permissible range." When the utility voltage sags too low or surges too high, the inverter opens its relays and waits — this is the protection working exactly as designed, not a breakdown.
It helps to place Error 15 beside its neighbors. Error 14 (Isolation Fail) is a DC-side problem on your roof wiring; Error 03 (Fac Fail) is the grid frequency being out of range; Error 23 (Utility Loss) is the grid vanishing entirely. Error 15 sits between the last two: the grid is present, but its voltage is outside the allowed window. Because voltage is a local phenomenon — it differs from street to street and even house to house — this fault is often specific to your connection rather than a suburb-wide event.
The most common everyday cause is the same midday voltage rise that troubles all solar streets: when every rooftop nearby exports at full power, local voltage climbs, and the homes electrically farthest from the transformer feel it most. GoodWe's guidance for Vac Failure reflects the grid-side nature of the fault: the inverter restarts by itself within about five minutes of the grid returning to normal, and the checks are to confirm the grid voltage conforms to specification and that the neutral (N) and earth (PE) wires are properly connected. Persistent faults, though, deserve investigation — chronic overvoltage slowly stresses appliances and the inverter alike.
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
- Midday voltage rise from heavy neighborhood solar exports, worst for homes far from the transformer.
- Utility supply voltage sitting near the top of its tolerance band on your street.
- A loose, corroded, or overheated AC connection raising impedance on your side of the meter.
- Undersized cable between the inverter and the switchboard, adding voltage rise during export.
- Incorrect country or grid-code setting in the inverter applying the wrong voltage limits.
- A tripped or faulty solar AC breaker or isolator interrupting the grid reference.
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 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
Call your installer or a licensed electrician if Error 15 appears daily, occurs at night or in dull weather, or is accompanied by flickering lights or appliance misbehavior. The installer can verify the country/grid-code setting, check cable sizing and connection tightness (including the N and PE wiring GoodWe's manual calls out), and liaise with the grid operator about supply voltage. A tripped breaker that will not stay on is an electrician-only job — never hold or tape a breaker closed.
Frequently asked questions
Is Error 15 the inverter's fault?
Usually not. Vac Failure means the grid voltage was out of range; the inverter is the messenger, disconnecting because the rules require it. If the fault is rare and brief, the grid simply had a bad moment.
How long before it starts working again?
GoodWe's documentation says the inverter restarts automatically within about five minutes of the grid returning to normal. No manual reset is needed.
What's the difference between Error 15 and Error 23?
Error 15 means the grid is there but its voltage is out of the allowed range. Error 23 (Utility Loss) means the grid is effectively gone — a blackout or a severed connection.
Should I report frequent Error 15 to my electricity company?
If it happens often, yes — ideally via your installer. Grid operators have obligations around supply voltage, and a log of timed faults from your monitoring app is the evidence they need.
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 — GoodWe GW XS Series User Manual (V2.8, EN), official GoodWe EMEA documentation (emea-test.goodwe.com) — Error Message table: 15 = "Vac Failure", "Grid voltage out of permissible range". Recovery and troubleshooting guidance (automatic restart within ~5 minutes; verify grid voltage conforms to specification; check N and PE wiring) from GoodWe's official XS troubleshooting notes (au-test.goodwe.com).