Sunsynk F34: AC Overcurrent Fault
F34 is an AC overcurrent on the Sunsynk's output. In plain terms, something is drawing more current than the output is allowed to deliver, and the usual reason is too much load on the backup (EPS) circuit. It is a close relative of F18 and is normally fixed by trimming the load.
What usually causes F34
- Too much load on the backup output, above the inverter's rating.
- A surge when a motor, pump or compressor starts.
- A faulty appliance drawing abnormal current.
How to clear it safely
- Reduce the load. Switch off heavy appliances on the backup circuit, motors and heaters first.
- Power-cycle. AC output breaker off, wait sixty seconds, back on. If it persists, also turn the DC isolator off, wait five minutes, and restart both.
- Add loads back one by one. Re-enable appliances gradually to find the one that trips it.
- Stay within the rating. Confirm the total backup load sits below the inverter's rated output power.
When to bring in a professional
If F34 returns with little or no load after a clean restart, the issue may be internal rather than an overload. Stop resetting it and contact your installer.
Related Sunsynk codes
FAQ
What's the difference between F18 and F34?
Both are AC-side overcurrent faults handled the same way: reduce load, restart, and find the culprit appliance. Treat them with the same approach.
It trips when my pump or A/C starts.
Motors draw a large inrush current at start-up. If that surge exceeds the limit, F34 trips. Staggering heavy start-ups or checking the appliance is within your Sunsynk's rating usually solves it.
Sources
- Sunsynk Hybrid Inverter User Manual (F34 = AC Overcurrent fault; keep backup load within the allowed power range).
- Sunsynk fault-code references and installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers external, switch-level steps only. Never open the unit or work on wiring unless qualified. When in doubt, call a licensed installer or electrician.