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Major and minor alarm codes for Huawei SUN2000 residential and commercial inverters, with plain-English causes and field-tested fixes.
A reference compiled by Solar Analytica from publicly available Huawei inverter documentation. It lists the fault and alarm codes a Huawei residential inverter may report, what each one means, and the documented resolution steps. Safety note: anything involving DC isolators, AC switches, wiring, or opening the unit is licensed-electrician work — if in doubt, contact your installer rather than working on a live system.
35 of 35 codes
Open-circuit voltage exceeds the maximum input voltage.
What to do
Contact your solar installer. Check the number of PV modules connected in series in the PV string, and ensure the string open-circuit voltage is no greater than the maximum operating voltage. Once the PV array is correctly configured, the alarm clears automatically.
The PV string power cable arcs or is in poor contact. Cause ID 1 = PV1, Cause ID 2 = PV2.
What to do
Contact your solar installer. Check whether the string cables arc or are in poor contact.
The PV string power cable arcs or is in poor contact. Cause ID 1 = PV1, Cause ID 2 = PV2.
What to do
Contact your solar installer. Check whether the string cables arc or are in poor contact.
The PV string is reverse-connected. Cause ID 1 = PV1, Cause ID 2 = PV2.
What to do
Contact your solar installer. Check whether the PV string is reverse-connected to the inverter.
Only a few PV modules are connected in series in the string, so its end voltage is lower than the other strings. Cause ID 1 = PV1, Cause ID 2 = PV2.
What to do
Contact your solar installer, who should check:
The AFCI self-check fails — either the AFCI check circuit is abnormal, or the AFCI circuit is faulty.
What to do
Turn off the AC output switch and DC input switch, then turn them on again after 5 minutes. If the fault persists, contact your solar installer, dealer, or Huawei technical support.
The impedance of the output phase wire is low, or it is short-circuited to PE.
What to do
Contact your solar installer. Check the impedance of the output phase wire to PE, locate the position with low impedance, and restore it.
The grid is experiencing an outage, the AC circuit is disconnected, or the AC switch is off.
The grid voltage is below the lower threshold, or the under-voltage duration exceeds the value specified by LVRT.
The grid voltage is above the upper threshold, or the over-voltage duration exceeds the value specified by HVRT.
The difference between grid phase voltages exceeds the upper threshold.
Grid exception: the actual grid frequency is higher than the local grid standard allows.
Grid exception: the actual grid frequency is lower than the local grid standard requires.
Grid exception: the rate of change of grid frequency does not comply with the local grid standard.
The grid voltage drops dramatically or the grid is short-circuited, so the inverter's transient output current exceeds the upper threshold and protection is triggered.
The DC component of the inverter output current exceeds the specified upper threshold.
The insulation impedance of the input side to PE decreases while the inverter is operating.
The N cable or ground cable is not connected. When a PV array is grounded, the inverter output is not connected to an isolation transformer.
What to do
Contact your solar installer. Power off the inverter and check:
The PV array is short-circuited to PE, or the array's environment is damp and insulation between the array and ground is poor.
What to do
Contact your solar installer, who should:
The inverter is installed in a poorly ventilated location, or the ambient temperature is too high.
What to do
Check the ventilation and ambient temperature at the install location. If ventilation is poor or the ambient temperature is above the upper threshold, improve airflow and heat dissipation. If both meet requirements, contact your dealer or Huawei technical support.
An unrecoverable fault has occurred on a circuit inside the inverter.
What to do
Turn off the AC output switch and DC input switch, then turn them on again after 5 minutes. If the fault persists, contact your dealer or Huawei technical support.
The upgrade did not complete normally.
The privilege certificate has entered its grace period; the privileged feature will become invalid soon.
Communication with the power meter is interrupted.
What to do
Contact your solar installer. Confirm the power meter settings match the actual model, that its communications parameters match the inverter's RS485 settings, that it is powered on, and that the RS485 cable is connected correctly.
The battery is faulty or disconnected, or the battery circuit breaker is off while the battery is running.
During a grid AC outage, the inverter proactively detects islanding.
What to do
Contact your installer. Check that the grid-connection voltage of the inverter is normal.
The inverter detects that the phase voltage exceeds the transient AC over-voltage protection threshold.
The off-grid output is overloaded or short-circuited.
PV module configuration does not meet requirements, or the module output is reverse-connected or short-circuited. Cause IDs — 2: too many optimisers in a single string; 3: too few optimisers in a string, or abnormal sunlight; 5: abnormal optimiser output voltage; 6: abnormal string or parallel connection; 7: string configuration changed.
What to do
Contact your installer. Check that the total number of PV modules, the number per string, and the number of strings meet requirements, and that module output is not reverse-connected.
The optimiser is offline or faulty.
What to do
Contact your dealer or Huawei technical support for optimiser replacement.
The inverter fails to communicate with the Smart Backup Box, or an unrecoverable fault has occurred inside the Smart Backup Box.
The output resistance of the PV arrays to ground is low, or the system insulation resistance is low.
What to do
Check the impedance between the PV array output and ground; rectify any short circuit or insufficient insulation. Alternatively, turn off the AC output and DC input switches, wait the period stated on the device safety label, then turn the DC input and AC output switches back on. If the alarm persists, contact your dealer or Huawei technical support.
The DI input is abnormal, or inconsistent with the configuration.
The DI input is abnormal, or inconsistent with the configuration.
The flash memory is insufficient, or it has bad sectors.
What to do
Turn off the AC output switch and then the DC input switch. After 5 minutes, turn on the AC output switch and then the DC input switch. If the fault persists, the board may need replacing — contact your dealer or Huawei technical support.
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