Fault Codes

The Fault Codes page allows users to review historical fault events recorded by the inverter. Each entry displays a fault code, description, date, and time the fault occurred. This function is helpful for diagnosing system issues, especially when troubleshooting installation or runtime errors.

What you can do from this page:

• View all recorded system faults in a list format.
• Check the fault code reference to understand the nature of the fault.
• Note the date and time to correlate events with grid conditions or system actions.
• Use the fault code to find troubleshooting steps in the technical manual.

The device’s status is primarily determined by the LED indicator light and whether the error reporting icon on the main page is displayed as OFF.

If any of the fault messages listed in the following table appear on your inverter and the fault has not been removed after re-starting, please contact your local vendor or service centre. The following information is required:

1. Inverter serial number.
2. Distributor or service centre of the inverter.
3. On-grid power generation date.
4. The problem description (including the fault code and indicator status displayed on the LCD) with as much detail

as possible.

5. Owner’s contact information.

In order to give you a clearer understanding of the inverter's fault information, we will list all possible fault codes and their descriptions when the inverter is not working properly.

Error Code	Display Error	Potential Method for Measurement and Fix
F07	DC/DC_Softstart_Fault	Startup problems, replace the control board, if not, remove the motherboard to measure the MOS tube is in good condition.
F10	AuxPowerBoard_Failure	Power supply failure, update power board.
F13	Working mode change	Inverter work mode changed: Reset the inverter. Seek help from Sunsynk.
F15	Short circuit protecting	Short circuit fault: Maintain the connection. Proceed to the settings to modify the work mode. Wait approximately 3-4 minutes. The device should return to its normal working condition, with the error cleared. Seek help from Sunsynk.
F18	AC over current fault or hardware	AC slide over current fault: Check if the backup load power is within the range of the inverter. Restart and check if it is normal.
F20	DC over current fault of the hardware	DC over current fault: Check PV module and battery connections. Reset the system.
F23	AC leakage current is trans over current	Leakage current fault: Check the PV module and inverter cables. You may have a faulty PV panel (earth short). Restart inverter.
F24	DC insulation impedance failure	PV isolation resistance is too low: Check if the connection of PV panels and inverter are firmly connected. Check if the earth bond cable on inverters is connected to the ground.
F26	The bus bar is unbalanced	Please wait 5 minutes to see if it returns to normal. Fully reset the inverter.
F29	ECAN communicate	When in parallel mode, check the parallel communication cable connection and hybrid communication address settings. During the parallel system startup period, inverters will report F29. When all inverters are in ON status, it will disappear automatically; If the fault exists, please contact us for help.
F30	Load current exceeding	Try tu reduce the load power. Seek help from Sunsynk.
F34	Over Load Protection	Reduce appliance power on LOAD side (system will auto-reboot in 2 minutes).
F35	No AC grid	Check if the inverter’s connected to the AC grid. Check if the RSCD had not tripped. Check if the switch and fuses between the inverter and grid are all switched on.
F37	Battery activation overcurrent	System will auto-reboot in 2 minutes.
F39	DC-DC over current	Push the power button of the inverter to restart it, system will auto-reboot in 2 minutes.
F40	DC over current	If the battery SOC shows 0, turn off the unit and restart it
F41	Parallel system stop	Check the hybrid inverter working status. If there’s 1pcs hybrid inverter is in OFF status, the other hybrid inverters may report F41 fault in parallel system. If the fault exists, please contact us for help.
F42	AC line low voltage	Grid voltage fault: Check if the voltage is in the range of standard voltage in specification, this can be adjusted via the grid set up page. Check if grid cables are correctly connected.
F45	AC line HIGH voltage	Grid exceeds 251V, and the inverter switch is off Grid exceeds 251V, and the inverter switch is on, but the battery is drained
F47	AC over frequency	Grid voltage fault: Check if the voltage is in the range of standard voltage in specification, this can be adjusted via the grid set up page. Check if grid cables are correctly connected.
F48	AC lower frequency	Grid frequency out of range: Check if the frequency is in the range of specification. You may need to adjust the frequency on the grid set up page.
F55	DC busbar voltage is high	User: External Battery Input voltage is high Installer: check inverter’s bus voltage might be too high. Observe the battery voltage value on the LCD (the value will be restored automatically if it is normal), if it is not normal for a long period, you have to check the control board or the voltage acquisition part of the motherboard.
F56	DC bus bar voltage is too low	Battery low voltage: Check if the battery voltage is too low. If the battery voltage is too low use the PV or grid to charge the battery. Check the battery BMS. Important: Especially with lithium batteries, ensure that the batteries Max. discharge current or power specification is the same or higher than the inverter specification.
F60	Smoke alarm	When the smoke alarm is lifted, use the App to restart the inverter (Refer to the relevant content of the App user manual).
F61	Bus one shutdown	Reset the inverter. Seek help from Sunsynk.
F62	DRMs0 stop	Reserved Error code
F63	FAN Error	A technician needs to check the internal fan wire or replace fan. Seek help from Sunsynk.
F64	Heat sink high-temperature failure	Heat sink temperature is too high: Check if the working environment temperature is too high. Turn off the inverter for 30 minutes and restart.

Debug

The Debug Screen provides advanced real-time diagnostic data from the inverter. This screen is useful for technicians and experienced users to observe live system status, flags, and performance readings.

To access the Debug screen:

• On the inverter’s front panel, press the following three buttons simultaneously for two seconds → Select + Up + Back.

The Debug screen will appear showing various internal parameters.

What You Can See on the Debug Screen:

• Live inverter flags and variables
• System operation statuses
• Voltage, power and frequency data
• Internal operational counters and state indicators

Notice

This screen is primarily intended for technical users. Most values are used for support diagnostics or firmware testing, and do not require user adjustment.