If your GoodWe inverter has suddenly stopped working or is displaying fault codes like “Isolation Fail”, “PV Over Voltage”, or “Relay-Check Fail”, you're in the right place. These GoodWe inverter error codes are designed to protect your solar system from damage—but understanding what they mean and what to do next can be confusing without a clear guide.

GoodWe inverters are packed with smart diagnostics that detect everything from grid voltage problems to internal component faults, ground insulation issues, and temperature sensor failures. While some codes resolve with a simple restart, others require professional attention—especially when related to leakage currents, relay faults, or DC input voltage anomalies.

In this guide, we’ve broken down all the most common GoodWe inverter fault codes and included detailed explanations and solutions for each one. Whether you’re using a DNS, MS, XS, or hybrid model, this page will help you identify faults and take action to restore your system.

PE Loss: GoodWe Inverter

The "PE Loss" error on a GoodWe inverter indicates a Protective Earth (PE) loss, meaning the inverter has detected a problem with the grounding connection. This safety mechanism prevents the system from operating when a proper earth connection is not detected, which could pose a risk of electric shock or equipment damage.

What It Means:
This fault typically points to a missing or faulty earth connection, possibly caused by loose wiring, corrosion, or damage to the grounding system. It's critical to have a properly functioning earth to ensure the safety of the solar installation and anyone around it.

Call us on 0405 685 441 to speak with a technician. We can help diagnose the issue over the phone or organise a site visit to inspect and repair the problem professionally.

System Failure: Isolation Fail

Description:
This Goodwe fault code indicates that the insulation resistance between the photovoltaic (PV) panels and the ground is too low, which can pose safety risks.

Troubleshooting Steps:

1. Disconnect the DC switch:
   Ensure all DC power is turned off before proceeding.
2. Check impedance between PV (+) & PV (-) to earth:
   Use a multi meter to measure the impedance.
• If impedance is less than 100 kΩ:
  Inspect the insulation of the PV string wiring to earth for any damage or degradation.
• If impedance is greater than 100 kΩ:
  Proceed to the next step.
3. Measure impedance between neutral and PE (Protective Earth):
   Disconnect the AC connector and measure the impedance.
• If impedance is higher than 10 kΩ:
  Examine the AC wiring for potential issues.

Note:
If these steps do not resolve the issue, please contact us at Solair Electrical for further assistance.

System Failure: Ground I Fail

Description:
This Goodwe inverter error signifies a ground fault, indicating a possible leakage current to the ground.

Troubleshooting Steps:

1. Disconnect the DC switch:
   Ensure all DC power is turned off safely.
2. Inspect the insulation of the PV string wiring to earth:
   Look for any signs of wear, damage, or degradation in the wiring insulation.
3. Reconnect the DC switch:
   After inspection, restore the DC connection.

Note:
If the problem persists after these steps, contact us on 0405 685 441 for a thorough evaluation.

System Failure: Vac Fail

Description:
This Goodwe inverter fault code occurs when the grid voltage is outside the acceptable range for the inverter.

Troubleshooting Steps:

1. Disconnect the DC switch and AC isolator:
   Ensure both DC and AC power sources are safely turned off.
2. Measure voltage between line and neutral in the AC connector:
   Use a multi meter to verify that the voltage aligns with the inverter's grid connection specifications.
• If the voltage does not conform:
  Inspect the grid wiring for any discrepancies or faults.
• If the voltage conforms:
  Reconnect the AC connector and DC switch. The inverter should automatically reconnect to the grid.

Note:
Should the issue continue, it's advisable to contact us on 0405 685 441 for further diagnostics.

System Failure: Fac Fail

Description:
This Goodwe error indicates that the grid frequency is outside the inverter's permissible range.

Troubleshooting Steps:

1. Automatic Restart:
   The inverter is designed to automatically restart once the grid frequency returns to normal parameters.

Note:
If the inverter does not resume normal operation after the grid frequency stabilises, contact us for assistance.

System Failure: Utility Loss

Description:
This Goodwe inverter error signifies a loss of connection between the inverter and the utility grid.

Troubleshooting Steps:

1. Disconnect the DC switch:
   Ensure all DC power is safely turned off.
2. Measure voltage between line and neutral in the AC connector:
   Verify that the voltage meets the inverter's grid connection specifications.
• If the voltage does not conform:
• Check if the Solar Supply Main Switch and inverter AC isolator are turned on.
• Ensure that the utility grid is functioning properly.
• If the voltage conforms:
  Reconnect the AC connector and DC switch.

Note:
If the problem persists, please contact us on 0405 685 441 for further investigation.

System Failure: PV Over Voltage

Description:
This error indicates that the PV string voltage exceeds the inverter's input voltage specifications.

Troubleshooting Steps:

1. Disconnect the DC switch:
   Safely turn off all DC power.
2. Check the PV string voltage:
   Measure the voltage to ensure it does not surpass the inverter's specified input voltage.
• If the voltage exceeds specifications:
  Reconfigure the PV panel string to align with the inverter's requirements.

Note:
For assistance with reconfiguration or if the issue persists, contact us for an inspection straight away

System Failure: Over Temperature

Description:
This Goodwe inverter fault code occurs when the inverter's operating temperature exceeds safe limits.

Troubleshooting Steps:

1. Verify installation position:
   Ensure the inverter's location complies with installation guidelines, allowing for adequate ventilation.
2. Reduce surrounding temperature:
   If possible, lower the ambient temperature around the inverter.
3. Improve ventilation:
   Move the inverter to a well-ventilated area or adjust its position to enhance airflow.

Need Help With a GoodWe Inverter Fault? Solair Electrical Is Ready

Some GoodWe inverter faults—like temporary grid errors—may clear on their own. But persistent issues like isolation failures, EEPROM faults, or DC sensor errors could mean deeper electrical or hardware problems that require an expert.

At Solair Electrical, we’re qualified to diagnose and repair all GoodWe inverter models—from older single-phase units to the latest hybrid and three-phase systems. Whether it's a safety lockout, system fault, or startup issue, we’ll locate the root cause and get your solar system back to full performance quickly and safely.

We service all of Brisbane, Redlands, Logan, and the Gold Coast with same-week appointments available.

Call 0405 685 441 today to book your GoodWe inverter service with Solair Electrical—your local solar repair specialists.