Sunsynk F26: DC Busbar Unbalanced
F26 tells you the Sunsynk's internal DC bus voltage has gone unbalanced. The DC bus is a voltage rail inside the inverter, and "unbalanced" means its two halves drifted apart. It is often a brief, transient condition, and on split-phase systems it can be linked to an uneven load across the two output legs. A restart settles most cases.
What usually causes F26
- A transient internal imbalance that settles by itself.
- Uneven loads in split-phase (L1/L2) systems, where one leg carries far more than the other.
- Occasionally an internal fault, if it keeps returning.
How to clear it safely
- Wait a moment. A transient F26 can clear on its own.
- Balance your loads (split-phase). If you run a split-phase system, spread heavy appliances more evenly across the two legs instead of stacking them on one.
- Restart. Power-cycle the inverter (AC off, DC isolator off, wait, restart). It may take two or three tries for the bus to settle.
- If F26 keeps returning, contact your installer to check the system.
Quick decision flowchart
F26 appears
↓ balance loads & restart
✅ Clears and stays gone → it was a transient or a load-balance issue.
❌ Keeps returning → have your installer check the inverter.
Related Sunsynk codes
FAQ
What is the "DC bus" in plain terms?
It is an internal voltage rail inside the inverter, sitting between the solar and battery input and the AC output. "Unbalanced" means the two halves of that rail drifted apart, which the inverter watches for and corrects.
I have a single-phase system. Why F26?
On single-phase units F26 is usually a transient that clears on restart. If it persists, it leans toward an internal issue for your installer to check.
Sources
- Sunsynk Hybrid Inverter User Manual (F26 = DC busbar unbalanced; verify split-phase load balance, restart).
- Sunsynk fault-code references and installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off". This guide covers external load balancing and a safe power cycle only. Internal faults must be checked by a licensed installer or electrician.