Critical What does this mean?
A safety-rated fault — there may be a risk of electric shock, fire, or equipment damage. Do not try to fix this yourself. Call a qualified electrician.
GoodWe Inverter Error 14 Isolation Fail — Low Insulation Resistance
Error 14 on a GoodWe inverter means "Isolation Fail": the inverter measured the insulation resistance between your solar-panel DC wiring and earth as too low, and shut itself down as a safety precaution. It most often appears on damp mornings or after rain, when moisture opens tiny leakage paths to ground. This is not a grid fault — it is on the roof side of your system. The inverter will try to recover on its own once conditions improve; if the error persists through dry, sunny hours, a panel or DC cable needs professional attention.
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 GoodWe inverter is transformerless, which means there is no heavy isolation transformer between your roof panels and the grid. To keep that design safe, the inverter measures the electrical insulation between the DC panel strings and earth every time it starts up — and keeps watching while it runs. GoodWe's official XS series user manual defines Error 14 as "Isolation Fail": "Ground insulation impedance is too low." In plain terms, the inverter found an easier path for electricity to leak from the DC side to earth than the safety limit allows, so it refuses to connect to the grid rather than risk energizing a faulty cable or panel frame.
There is a signature pattern worth knowing: isolation faults love wet weather. Dew, fog, rain, and morning condensation let a microscopically damaged cable or a tired panel junction box leak just enough current to trip the test at startup, then dry out by midday and pass again. GoodWe's own troubleshooting guidance notes exactly this — the fault shows up early in the morning, late in the evening, or in rainy weather when air humidity is high. An error that follows the weather is still a real insulation problem, just an intermittent one; it will not heal on its own and usually gets worse as the damaged spot degrades further.
Error 14 sits on the DC side of the system, which distinguishes it from GoodWe's grid-side errors. Error 15 (Vac Failure) is the grid voltage being out of range, and Error 03 (Fac Fail) is the grid frequency being out of range — both of those are your electricity network's problem. Error 14 is your array's problem: panels, DC cables, connectors, and grounding on the roof side. That is also why it carries the higher severity — leakage current to earth is a genuine shock and fire risk, not just a production nuisance.
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
- Moisture inside a panel junction box or MC4 connector after rain, heavy dew, or fog.
- A cracked, abraded, or rodent-chewed DC cable letting water reach the conductor.
- A damaged panel backsheet or loose panel frame ground lowering insulation to earth.
- Incorrect neutral-to-earth (N-PE) wiring on the AC side, which GoodWe's manual lists as a cause of false isolation readings.
- Condensation forming inside an outdoor DC isolator or the inverter's connection area overnight.
- An aging panel developing internal cell-to-frame leakage, which shows up first in damp conditions.
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 a qualified solar electrician promptly if Error 14 persists in dry weather, appears every morning, is accompanied by any burning smell or discolored connectors, or if the system has produced nothing for more than a couple of days. Isolation testing involves live DC at hundreds of volts, and disconnecting DC strings under load can draw a sustained arc — this is strictly professional work. Never open the inverter or pull DC connectors yourself.
Frequently asked questions
Will Error 14 clear on its own?
Often, yes — temporarily. The inverter re-tests insulation at every start-up, so a moisture-driven fault can vanish by midday and return the next damp morning. The underlying damage does not fix itself, so a repeating pattern still needs an electrician.
Is Error 14 dangerous?
It can be. Low insulation means DC current may be leaking toward earth, which is a shock and fire risk. The inverter shutting down is the protection working. Treat a persistent fault as urgent and keep people and pets away from the array area.
Can I just hose down my panels to clean them when this happens?
No — adding water is the opposite of what an isolation fault needs, and wet electrical equipment plus a person with a hose is a bad combination. Wait for dry conditions and have a professional inspect first.
How is Error 14 different from Error 15?
Error 14 is a DC-side insulation problem on your roof wiring; Error 15 (Vac Failure) is the AC grid voltage being out of range. Different sides of the inverter, different causes, different fixes.
Need a professional?
This fault is a safety risk — do not attempt to fix it yourself. 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: 14 = "Isolation Fail", "Ground insulation impedance is too low". Moisture/timing guidance from GoodWe's official isolation-fault troubleshooting notes (community.goodwe.com).