Sunsynk F29: Parallel CAN-bus Fault
F29 only turns up when you have more than one Sunsynk wired in parallel. It means they lost the CAN communication link between them, so they can no longer coordinate. It is almost always a cable, termination or address issue, and it often shows briefly during start-up before the units sync.
What usually causes F29
- A loose or wrong parallel comms cable between the inverters.
- Incorrect addressing or termination, where each inverter needs the right address and the chain needs its termination set.
- One inverter off or still starting, so the others cannot reach it. F29 can clear once all units are running.
How to clear it safely
- Wait through start-up. F29 frequently clears once all parallel inverters have fully powered up and synced.
- Check the parallel comms cables. Make sure the CAN cables between inverters are firmly seated in the correct ports at both ends.
- Verify addresses and termination. Confirm each inverter's parallel address and the termination settings follow Sunsynk's parallel-install guide.
- Confirm every unit is on. All inverters in the group must be powered.
- Restart the group if needed. If F29 persists, your installer should review the parallel configuration.
Quick decision flowchart
F29 appears
↓ all units on, cables + addresses correct?
✅ Clears after start-up / reseating cables → comms restored.
❌ Persists → parallel cabling, address or termination needs review.
Related Sunsynk codes
FAQ
I only have one inverter. Can I get F29?
F29 is specific to parallel (multi-inverter) setups. On a single inverter it should not normally appear; if it does, contact your installer.
F29 shows every morning at start-up then goes away.
That is common: the units handshake as they wake up. A brief start-up F29 that clears once everything is running is usually nothing to worry about.
Sources
- Sunsynk Hybrid Inverter User Manual (F29 = Parallel CANBus fault; check parallel comms cable and inverter address settings).
- Sunsynk fault-code references and installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers the low-voltage comms cabling and settings only. Parallel power wiring and configuration should be handled by a licensed installer.