- Solar and energy
- Solar inverter
Isolation Failure
GoodWe Isolation Failure on a solar inverter: low earth insulation
Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
The GoodWe inverter has detected ground insulation impedance that is too low (code 14, Isolation Fail, on the XS series). Do not touch the DC switch or DC connectors: note the time and weather and contact your installer.
Safety first
Stop and check this first
- Do not open the DC switch or unplug panel connectors to test. GoodWe restricts installation and maintenance to qualified professionals.
Safe checks you can perform
- Message, time and weather conditions
- How often the fault appears in the history
- Impedance of each string to earth
Leave these tasks to a qualified professional
- Do not attempt this professional task: Insulation measurement of each string
- Do not attempt this professional task: Neutral to earth and inverter earthing
- Do not attempt this professional task: Test start-up after the repair
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Insulation measurement of each string
What they doThe installer measures PV+ and PV- impedance to earth on each string with the system disconnected and locates the section with low insulation.
They must show youeach string's measured value against the minimum in your model's manual.
In writingwhich string failed, where, and what was repaired.
Neutral to earth and inverter earthing
What they doWith the AC connector removed, the installer measures neutral to earth impedance and checks the inverter earth (PE) connection.
They must show youthe neutral to earth reading and the inverter PE connection.
In writingmeasured values and the state of the earthing.
Test start-up after the repair
What they doAfter the repair, the installer reconnects and confirms the inverter goes from Waiting to Normal without the fault returning.
They must show youthe display in Normal and a history with no new alert.
In writingtest date and the readings taken after the repair.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Message, time and weather conditions
- Who:
- you, no tools.
- How:
- read the alert on the display or in the SolarGo app or SEMS Portal and write down date, time and whether there is rain, dew or humidity. GoodWe asks for this information before contacting after-sales.
- Result that matters:
- when the fault appears and in what weather.
- If it only appears with rain or in the morning:
- note it, it is key information for the installer to locate the point.
- If it also appears in dry weather:
- the installer must still search; no cause is ruled out.
- Evidence to keep:
- photos or screenshots of the alert with date, time and weather.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW
How often the fault appears in the history
- Who:
- you, no tools.
- How:
- on the LCD open the Error History menu, or check alarms in the SolarGo app, and count how many times the fault appears.
- Result that matters:
- whether it is a one-off alert or repeats daily.
- If it repeats every day:
- report it to the installer as a persistent fault.
- If it appeared only once:
- still note it; the installer decides whether to measure.
- Evidence to keep:
- screenshot of the history with the date of each alert.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW · XS SERIES USER MANUAL Ver2.6 EN
Impedance of each string to earth
- Who:
- a qualified PV installer.
- How:
- open the DC switch, remove the DC connectors and measure the impedance of PV+ and PV- to earth; then remove the AC connector and measure between neutral and earth.
- Result that matters:
- the measured value for each string against the minimum set in the manual for your model.
- If a string is below it:
- the fault is in the insulation of that string's wiring to earth.
- If all strings are above it:
- the manual refers you to the GoodWe service office.
- Evidence to keep:
- table with each string's reading and the neutral to earth reading.
PV strings carry high DC voltage in daylight and disconnecting under load can cause an arc. Only a qualified installer with the right equipment does this.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW · MANUAL DE USUARIO DE LA SERIE XS INVERSOR SOLAR
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Solar and energy
- Brand
- GoodWe
- Product type
- Solar inverter
Known code variants
- GoodWe error 14
- GoodWe fallo de aislamiento
- GoodWe insulation fault
- GoodWe Isolation Fail
- GoodWe Isolation Failure
What it means
GoodWe defines this fault as ground insulation impedance that is too low. The inverter monitors the impedance between the PV+ and PV- poles of the PV strings and earth. The manual asks for that impedance to be measured, for the insulation of the string wiring to earth to be checked and for the neutral to earth impedance on the AC side to be measured; for the DNS series it adds making sure the inverter is earthed. The code does not say which string or point is leaking, and on its own it does not prove the inverter is faulty.
Warnings and stop conditions
- Higheditorial warning
Do not open the DC switch or unplug panel connectors to test. GoodWe restricts installation and maintenance to qualified professionals.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW
Symptoms and causes
Probable causes · in order
- Low insulation in string wiringPossible
This is the manual's main path: low impedance between PV+ or PV- and earth in the string wiring. It is confirmed when one string measures below the manufacturer's minimum.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW
- Neutral to earth problem on the AC sidePossible
The manual also asks for the impedance between neutral and earth to be measured with the AC connector removed. Suspect it when every string measures correctly.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW · MANUAL DE USUARIO DE LA SERIE XS INVERSOR SOLAR
- Inverter not properly earthedPossible
For the DNS series GoodWe asks you to make sure the inverter is earthed. It is checked at the inverter PE connection, independent of any single string.
Evidence: NS.DNS Series User Manual Ver1.05 EN
- Fault in the inverter itselfPossible
If string impedance is above the minimum, GoodWe refers you to the local service office. Only then is the unit assessed, never before the strings are measured.
Evidence: User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW
Virtual technician
Does Isolation Failure still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
User Manual V1.7-2026-08-20 Grid-Tied PV Inverter XS Series 0.7-3.3kW
GoodWe Technologies Co., Ltd. · 2026 · manual
- 2
XS SERIES USER MANUAL Ver2.6 EN
GoodWe Technologies Co., Ltd. · 2022 · manual
- 3
NS.DNS Series User Manual Ver1.05 EN
GoodWe Technologies Co., Ltd. · 2021 · manual
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