Is your Sunsynk Hybrid Inverter showing an error? This comprehensive database covers fault codes for all major models, including the SUN-5K-SG01LP1, SUN-8K-SG01LP1, and the 12kW/16kW three-phase series.
| Code | Description | Solutions |
|---|---|---|
| F08 | GFDI_Relay_Failure | Check backup load port N line connection to ground (Split/3-phase systems). |
| F13 | Working mode change | Grid type/frequency or battery mode changed. Restart system if it doesn’t clear. |
| F18 | AC over current (Hardware) | Check backup/common load power range. Restart inverter. |
| F20 | DC over current (Hardware) | Check PV/Battery connections. Reduce load for off-grid startup. |
| F22 | Tz_EmergStop_Fault | Contact installer for help. |
| F23 | AC leakage transient current | Check PV side ground. Restart system 2-3 times. |
| F24 | DC insulation impedance failure | Check PV panel connections and inverter PE cable grounding. |
| F26 | DC busbar unbalanced | Check L1/L2 load balance in split-phase mode. Restart 2-3 times. |
| F29 | Parallel CANBus fault | Check parallel comm. cable and inverter address settings. |
| F34 | AC Overcurrent fault | Check backup load range; ensure it is in allowed power range. |
| F35 | No AC grid / No Utility | Confirm grid status. Check grid connection and AC switches. |
| F41 | Parallel system stop | Check if one parallel inverter is OFF. |
| F42 | AC line low voltage | Verify grid voltage range and check AC cable connections. |
| F47 | AC over frequency | Check if grid frequency is within specifications. |
| F48 | AC lower frequency | Check if grid frequency is within specifications. |
| F56 | DC busbar voltage low | Battery voltage is low. Use PV or Grid to charge. |
| F58 | BMS communication fault | Inverter lost comms with battery BMS. Check cables or disable BMS_Err_Stop. |
| F63 | ARC fault | Check PV module cable connections and clear the fault. |
| F64 | Heat sink high temperature | Check ambient temperature. Turn off for 10 mins and restart. |
Common Sunsynk Fault / Error Codes
How to resolve Sunsynk F56 fault code?
This Code primarilyindicates that the DC Busbar voltage is too low. This usually means the battery cannot supply the power requested by the inverter, or there is a communication/connection break between the two.
- Check Battery Connections: Ensure all battery cables are tight and making good contact. Check for loose terminals or damage.
- Verify Fuses/Breakers: Check the DC disconnect or breaker and battery fuses. A popped fuse will prevent voltage from reaching the inverter even if the battery is on (Blown fuses are a very common cause).
- Perform a System Restart: Turn off the AC (grid) input, then the solar (PV), and finally the battery. Wait at least 60 seconds before switching them back on in the reverse order (Battery → PV → AC).
- Check Charge Level (SOC): If the battery is below its shutdown percentage (often 20%), the inverter will trip. Force a charge from the grid if available to bring the voltage back up.
2. What to check next.
- Max Discharge Amperage: If your battery is rated for 50A but your inverter tries to pull 100A during a heavy load (like an air conditioner starting), the BMS will trip. Lower the “Max Discharge” setting to match your battery’s C-rating.
- Battery Mode Selection: Ensure the correct battery type is selected. For lithium batteries with a communication cable, select “Lithium”. If there is no communication cable, use “Voltage” or “AGM” mode and manually set the correct voltages.
- BMS Communication: Confirm the CAN/RS485 cable is properly plugged in. If the inverter loses communication with the battery management system (BMS), it may default to a low-voltage error.
3. Other Possible Causes
- Undersized Battery Bank: If your inverter is 8kW but your battery can only provide 2.5kW (0.5C rating), the system will trip whenever loads exceed the battery’s physical limit.
- Cable Length Imbalance: In parallel setups, if battery cables aren’t the same length, current won’t pull evenly, causing one battery to “sag” and trigger the fault.
- Faulty BMS: A damaged internal battery management board may report incorrect voltage data, requiring a battery firmware update or repair.
Safety Note
Always ensure that the batteries and system is off before pulling the fuses to check for continuity, and checking cables or lugs for damage or loose connections.
Always follow correct shutdown procedures
What is the Sunsynk F18 fault code?
This Code normallyindicactes the load through the inverter is too high. This usually means there is more current on the AC load that the inverter can handle.
What to do for F18
Reduce the load by turning off appliances, plugs and any heavy loads, you can isolate the heavy loads by turn them back on one at a time monitor load on the inverter screen determine which loads cant run simultaneously or needs to be isolated an moved from essentials load.
*reduce load and restart the inverter – this fault should clear.
