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 — Causes and Safe Fixes
GoodWe error 15 (“Vac Failure”) means the voltage coming from your electricity grid is outside the range your inverter is allowed to operate in — too high or too low. The inverter disconnects from the grid to protect itself and your home, and it reconnects automatically once grid voltage returns to normal. This is a grid problem, not an inverter problem, and it usually needs no action from you.
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
GoodWe's XS series user manual describes error 15 as “Vac Failure: grid voltage out of permissible range.” Your inverter is a grid-following device: it is only allowed to feed power when the grid voltage and frequency sit inside strict limits set by your country's grid code. When the utility voltage drifts outside those limits, the inverter must disconnect — that is the regulation, not a malfunction. Error 15 is the inverter telling you it did exactly what it is required to do.
The usual culprit is the grid itself. Voltage rises when lots of solar systems in your street export at once — a sunny midday with low local demand is the textbook case — and it sags during peak evening demand or when there is a fault upstream. Long cable runs between your home and the street transformer make the swings bigger at your meter. Occasionally the cause is inside your property — a loose AC connection or an undersized AC cable adding extra voltage rise — but grid conditions are far more common, especially when the fault follows a daily rhythm.
Because the cause is external, the fix is usually patience. GoodWe inverters automatically resume grid feed-in once the voltage stays within limits for the required check period. If error 15 appears briefly and clears, there is nothing to do and nothing to reset. If it happens daily at the same time, the pattern itself is the useful information: log it and report it to your grid operator, because persistent overvoltage in solar-heavy streets is a known issue that utilities are obliged to investigate.
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
- High grid voltage from excess local solar export — the classic midday overvoltage in streets with many rooftop systems feeding in at once.
- Low grid voltage during peak demand — heavy evening loads dragging the local network voltage down.
- Long distance from the street transformer — voltage swings are larger at the far end of a feeder.
- Loose or corroded AC connections on your property — raising the voltage the inverter sees at its terminals.
- Undersized AC cabling between inverter and switchboard — extra voltage rise across a thin or over-long cable under export.
- Grid operator works or upstream faults — temporary voltage excursions during maintenance or after a network fault.
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 if error 15 persists for hours, appears every day, or shows up together with a tripped breaker or a burning smell. If the problem is street-wide, your grid operator — the company that owns the poles and wires — is the right contact: they can log the voltage at your meter and adjust the local transformer tap. Never attempt to adjust the inverter's voltage protection limits yourself: those are set to your country's grid code, changing them is illegal in most regions, and only qualified personnel may touch protection settings. Any AC wiring checks are electrician-only work.
Frequently asked questions
Is GoodWe error 15 a fault with my inverter?
Almost never. It means your inverter detected abnormal grid voltage and disconnected to protect itself — it is doing its job. The inverter is the messenger here, not the problem.
Will error 15 clear by itself?
Yes, in most cases. Once the grid voltage returns to the permitted range and stays there, the inverter automatically reconnects and resumes feeding power. No reset is needed.
Can I change the voltage limits to stop it tripping?
No — and you should not try. The limits are set to your country's grid safety standard, and only qualified personnel may adjust protection settings where local rules allow it at all.
Who do I complain to about constant error 15?
Start with your grid operator (the network company that owns the poles and wires, not your electricity retailer). They are responsible for keeping voltage within limits and can investigate persistent overvoltage in your street. Keep a log of when error 15 appears — dates and times help their investigation.
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 Grid-Tied PV Inverter User Manual (EN), official GoodWe manual hosted on emea-test.goodwe.com (GoodWe EMEA download site) — Error Message table: 15 = “Vac Failure”, “Grid voltage out of permissible range”. Grid-fault auto-recovery behaviour and AC-side troubleshooting (breaker/connection checks, automatic grid-tie resumption) per GoodWe's official GW series user manual (admin.goodwe.com).