GoodWe Inverter Error Codes and Troubleshooting Guide for UAE Solar Systems

GoodWe ET and ET Plus three-phase hybrid inverters are widely installed across residential villas and light commercial rooftops in Dubai and the northern Emirates under DEWA Shams Dubai regulations. While these units are engineered for robust power conversion, operating in high ambient desert temperatures and interfacing with regional grid networks can trigger specific operating alarms.

When an operational fault occurs, the inverter display illuminates a warning LED and logs an error code to the local LCD panel and the GoodWe PV Master mobile application. Understanding the root cause of each fault signature allows facilities managers and solar technicians to isolate issues rapidly without compromising system safety or warranty coverage.

Grid Synchronization and AC Interface Alarms

Grid-tied hybrid inverters maintain continuous monitoring of the local utility network before synchronizing and exporting solar power. Any deviation outside the configured grid code halts power conversion immediately.

Utility Phase Failure (L2 and L3 Reversal)

The Utility Phase Failure alarm indicates that the sequence of the on-grid AC wiring is incorrect. Specifically, the inverter has detected that the phase angles of L2 and L3 are reversed, meaning the L2 and L3 cables are connected in reverse order at the AC terminal block or AC isolator.

Safety Warning: Before inspecting AC terminal connections, switch off the AC isolator switch and open the main AC distribution breaker. Confirm zero AC voltage across all phase terminals using a calibrated multimeter before touching conductors.

To rectify Utility Phase Failure:

1. De-energize the AC supply at the main solar distribution sub-board.
2. Verify the phase rotation of the utility supply at the incoming AC isolator terminals using a three-phase phase-rotation meter.
3. If the utility phase sequence is confirmed correct, swap the positions of the L2 and L3 phase conductors at the inverter AC terminal plug.
4. Re-torque conductor terminals to manufacturer specifications, re-energize the AC breaker, and confirm that the inverter successfully synchronizes with the grid.

Utility Loss

The Utility Loss alarm signifies that public grid power is not available, power is lost, or the on-grid connection fails because the inverter does not detect the connection of the grid.

In Dubai villa installations, this commonly occurs during scheduled DEWA feeder maintenance, a tripped AC miniature circuit breaker (MCB), or a blown fuse inside the external solar generation switchboard. Technicians should verify that the AC distribution breaker is engaged and measure line-to-line and line-to-neutral voltages at the AC terminals to ensure nominal supply.

Vac Failure and Fac Failure

The Vac Failure alarm triggers when the grid voltage is not within the permissible range, meaning the inverter detects that AC voltage is beyond the normal range required by the safety country setting. Similarly, the Fac Failure alarm indicates that the grid frequency is not within the permissible range because the inverter detects that grid frequency is beyond the normal range required by the safety country.

During peak summer generation hours in UAE suburbs, local transformer feeders can experience voltage rise when multiple rooftop systems export simultaneously. If grid voltage rises above regional thresholds, the inverter disconnects to protect connected household appliances. Confirm with a multimeter whether the utility supply voltage is within limits at the main distribution board; persistent out-of-range readings require utility grid coordination.

DC Array and Solar String Faults

DC faults involve open-circuit overvoltages or breakdown of conductor insulation on the rooftop array.

PV and Battery Overvoltage

The PV or Bat Overvoltage alarm occurs when the PV or battery voltage is too high. This is triggered when the total open-circuit voltage (Voc) of each PV string is higher than the maximum DC input voltage of the inverter, or when battery voltage exceeds the maximum battery input voltage of the inverter.

In the UAE winter months, cool morning ambient temperatures combined with high solar irradiance cause photovoltaic panel open-circuit voltage to rise significantly. If a string was designed near the maximum inverter DC voltage rating without accounting for the negative temperature coefficient of voltage, morning string Voc will exceed safe limits. Technicians must measure open-circuit DC voltage with a calibrated DC voltmeter and reconfigure string sizing by removing one or more series modules if Voc exceeds maximum inverter ratings.

Isolation Failure (Ground Insulation Impedance Low)

Isolation Failure occurs when the ground insulation impedance of the PV string is too low. GoodWe engineering documentation notes that isolation failure could be caused by multiple reasons, such as PV panels that are not grounded well, a DC cable that is broken, aged PV panels, or comparatively heavy surrounding humidity.

In coastal UAE regions such as Dubai Marina, Jumeirah, and Sharjah, morning relative humidity often condenses on rooftop arrays. If moisture penetrates cracked MC4 connector seals or cable insulation worn by wind-blown abrasive sand, DC leakage current passes to the aluminum racking.

To systematically trace an Isolation Failure:

1. De-energize the inverter by turning the DC isolator switch to OFF and disengaging the AC breaker.
2. Disconnect each PV string from the inverter DC input terminals.
3. Use a multimeter to check if the resistance between earth and inverter frame is close to zero, ensuring that the inverter chassis earthing conductor is securely bonded.
4. Perform an insulation resistance test between the positive DC conductor and earth, and between the negative DC conductor and earth for each individual string.
5. Inspect roof cabling for mechanical abrasions against tile edges or cable tray entry points, and replace damaged MC4 connectors with genuine sealed connectors.

Environmental and Internal Inverter Protections

Desert conditions subject power conversion electronics to extreme ambient heat, thermal cycling, and airborne mineral dust.

Over Temperature Shutdown

The Over Temperature alarm indicates that the temperature inside of the inverter is too high, meaning the working environment of the inverter leads to a high-temperature condition.

When ambient temperatures in Dubai peak during summer, inverters mounted on exposed rooftop parapets or exterior walls absorb intense radiant heat. To protect sensitive IGBT semiconductor switches and internal capacitors, the inverter derates power output and ultimately initiates an automated thermal shutdown.

GoodWe operating guidelines specify a structured cooling step:

• Close the inverter for 15 mins to allow internal thermal dissipation, then start up again.
• Inspect the heat sink fins located on the rear of the inverter chassis. Remove accumulated desert dust, sand, and debris using dry compressed air or a soft brush.
• Verify that manufacturer installation clearances around the chassis are maintained to allow unrestricted convective airflow.
• If the unit is installed in direct sunlight, construct a ventilated solar shading canopy over the inverter chassis that deflects direct UV radiation without obstructing convective heat dissipation.

Ground Failure and High Neutral-to-Earth Voltage

The Ground Failure alarm signals that ground leakage current is too high. This fault could be caused by multiple reasons, including an AC side neutral cable that is not connected well or comparatively heavy surrounding humidity.

Under normal operating conditions, the voltage should be lower than 10 V between the N and PE cable on the AC side. If the AC neutral terminal is loose, or if desert soil aridity causes the building earthing pit impedance to drift upward, a floating potential develops between neutral and protective earth.

Technicians must measure the AC voltage between the neutral (N) terminal and protective earth (PE) terminal using a true-RMS multimeter:

• If the reading exceeds 10 V, inspect the main distribution board neutral-earth bonding and tighten all neutral bar terminal screws.
• Measure earthing electrode resistance to ensure compliance with DEWA wiring regulations.

Internal System Alarms and Backup Circuit Management

Hybrid inverters feature internal diagnostics to safeguard both internal switching components and critical backup sub-circuits.

Relay Check Failure and DC Injection High

The Relay Check Failure alarm indicates an internal self-checking relay failure, which can be caused by neutral and ground cables that are not connected well on the AC side, or simply an occasional self-test failure. Technicians should verify AC neutral and earth conductor continuity; if the wiring is secure and the alarm persists across multiple restarts, internal contactor wear may necessitate inverter service.

The DC Injection High alarm triggers when the inverter detects a higher DC component in the AC output. GoodWe guidelines advise technicians to restart the inverter to clear transient measurement anomalies. If the error reoccurs immediately upon grid synchronization, the internal current sensing circuit requires factory diagnostic review.

Back-up Over Load

On hybrid systems supplying dedicated critical load sub-panels, the Back-up Over Load alarm indicates that the backup side is overloaded. This occurs when the total backup load power is higher than the backup nominal output power of the inverter.

To resolve backup overload conditions:

• Immediately decrease backup loads to make sure the total load power is lower than the backup nominal output power.
• Audit the critical load distribution board to ensure that high-surge inductive loads, such as large central air conditioning compressors or pool pumps, have not been wired to the backup output.
• Isolate non-essential circuits before attempting to restart the inverter in backup islanding mode.