Sunways Inverter FAQs & Troubleshooting

“Mains Lost” indicates that the inverter is not detecting the AC grid supply. Check whether there is a power outage at the property and note whether other electrical equipment has also lost power. If the grid supply is available but the message remains, ask your installer to check the AC supply path and connections using the manual for your inverter.

“Grid Voltage Fault” indicates that the detected grid voltage is outside the configured protection range. Record the message, the displayed reading and when it occurs. Ask your installer to check the local supply, AC installation and approved settings for your exact model and installation location. Do not change the country profile or widen protection limits to clear the alarm.

“Grid Frequency Fault” indicates that the detected grid frequency is outside the configured protection range. Record whether the message coincides with a grid disturbance. If it remains or returns, ask your installer to verify the supply and the correct installation-country settings. Changing to a different country profile is not a general troubleshooting step.

“DCI Fault” relates to the DC component detected in the inverter’s AC output. Record the exact message and contact your installer if it persists. Any restart or diagnostic procedure should follow the user manual for your exact model; do not use a restart sequence from a different inverter.

“ISO Over Limitation” indicates that the inverter has detected low insulation resistance. Note whether the message appears during wet weather or after work on the installation. Ask a qualified installer to inspect the relevant wiring and insulation according to the model’s manual. Do not disconnect PV strings or carry out electrical measurements yourself.

“GFCI Fault” indicates that the inverter has detected excessive leakage current. Record when the alarm appears and whether weather conditions or recent installation work coincide with it. Ask your installer to investigate the insulation and relevant circuits. Weather-related timing alone does not confirm the cause or show that the installation is safe.

“PV Over Voltage” indicates that the inverter has detected a PV input voltage above its permitted limit. Ask your installer to compare the PV string design and measurements with the datasheet and user manual for the exact inverter model. Do not remove panels or disconnect PV connectors yourself.

“Bus Voltage Fault” concerns the inverter’s internal DC bus voltage. The fault message alone does not establish whether the cause is the PV input or an internal issue. Record the message and ask your installer or Sunways technical support to identify the checks required for your exact model.

“Inverter Over Temperature” indicates that the inverter has detected an excessive internal temperature. From a safe position, check whether its ventilation area is visibly obstructed and note the surrounding conditions. Ask your installer to verify the installation clearances and cooling requirements in the correct user manual. Contact support if the alarm persists.

Record “SPI Fault” exactly as displayed, together with the inverter model and the time of the event. Ask your installer or Sunways technical support to confirm its meaning and the required checks for that model. Do not assume that the message identifies a particular external cause or requires a component replacement.

Record “E2 Fault” exactly as displayed and contact your installer or Sunways technical support with the inverter model, serial number and any accompanying messages. The correct diagnostic and restart procedures must be identified from the manual for that model.

“GFCI Device Fault” concerns the inverter’s leakage-current detection device. Keep the full alarm name when contacting support so that it is not confused with “GFCI Fault.” Your installer should use the correct model documentation to determine the next checks and whether service is required.

“AC Transducer Fault” concerns the inverter’s AC sensing function. Record the full message and any other alarms, then contact your installer or Sunways technical support. The message alone is not enough to decide which part needs repair or replacement.

“Relay Check Fail” indicates a problem reported during the inverter’s relay check. Ask a qualified installer to investigate using the manual for your exact model. Do not apply a universal voltage threshold or assume that the message proves a particular wiring fault. Include the alarm photo and inverter details in your support request.

“Internal Fan Fault” indicates a reported problem with the hybrid inverter’s internal fan. Record the message and contact your installer or Sunways technical support. Internal inspection and any fan replacement should be performed by qualified service personnel following the model’s service instructions.

“External Fan Fault” indicates a reported problem with the hybrid inverter’s external fan. Note any visible obstruction without opening the equipment or reaching into the fan area. Ask your installer to follow the correct isolation and inspection procedure before deciding whether cleaning or replacement is needed.

“Bus Voltage Hard Fault” is a bus-voltage-related alarm on the hybrid inverter. Record the full wording so that support can distinguish it from other bus voltage messages. Contact your installer or Sunways technical support for the diagnostic procedure that applies to your exact model.

“PV Power Low” indicates low PV power at the hybrid inverter. Check whether sunlight is limited or the array is visibly shaded, without accessing the roof or touching electrical equipment. If the message continues under otherwise suitable conditions, ask your installer to investigate the PV system.

“Bat OV” is a battery-overvoltage message shown by the hybrid inverter. Record both the inverter message and any alarm shown on the battery. Contact your installer with the inverter and battery model details so that the permitted operating range and installation can be checked against their documentation.

“Backup OV” indicates an overvoltage condition reported at the hybrid inverter’s backup output. Note whether backup operation is affected and record any accompanying messages. Ask your installer to check the backup installation using the correct user manual; do not alter its wiring yourself.

“Bus Volt Low” indicates that the hybrid inverter has detected a low internal bus voltage. Record the exact message and operating conditions, then contact your installer or Sunways technical support. The fault name alone does not identify the component or connection responsible.

“Hard Fault” is a general fault message that requires the exact inverter model and any accompanying alarm information to interpret. Send a photo of the display, the serial number and a description of what happened before the message appeared to your installer or Sunways technical support.

“Backup OP” indicates an overload at the hybrid inverter’s backup output. Where safe, switch off non-essential appliances connected to the backup supply using their normal controls. If the message remains, ask your installer to compare the connected loads with the backup limits in the exact model’s documentation.

“Inverter OV” is described here as a backup-output overvoltage alarm. Record the full wording and contact your installer with the inverter model and operating conditions. Ask the installer to confirm the code against the correct manual before diagnosing the backup circuit.

“Inverter OF” is described here as a backup-output overfrequency alarm. Record whether the system was supplying backup loads when it appeared. Your installer or Sunways technical support should confirm the model-specific meaning and next steps before any settings are changed.

“Inverter OC” is described here as a backup-output overcurrent alarm. Record the loads that were operating when it occurred and contact your installer. The installer should confirm the alarm meaning and assess the backup circuit using the documentation for your exact model.

“Phase Order Err” indicates a reported phase-sequence problem. Record the message and ask a qualified installer to verify the installation against the inverter’s wiring instructions. Do not change phase connections or attempt electrical measurements yourself.

“SCI Fault” is an internal-communication-related message on the hybrid inverter. Record any accompanying alarms and contact your installer or Sunways technical support. The model documentation is needed to identify the relevant communication path and diagnostic procedure.

“FLASH Fault” is an internal-storage-related message on the hybrid inverter. Send the exact alarm text, inverter model and serial number to your installer or Sunways technical support. Do not install firmware or use reset instructions intended for a different model.

“Meter Comm Fault” indicates a communication problem between the hybrid inverter and the meter. Record the inverter and meter model details and whether the message followed installation work. Ask your installer to check the communication connection and meter configuration against the relevant manuals.

“Battery Fault” means that the hybrid inverter is reporting a battery-related fault. Check whether the battery also displays an alarm and record that message or indicator pattern without opening the equipment. Provide both product models and the alarm details to your installer or Sunways technical support.