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Sunsynk F63: Arc Fault Detected (AFCI)

Updated June 2026 · Reviewed for technical accuracy · ~3 min read
This is a fire-risk safety code. F63 means your Sunsynk's arc-fault detector (AFCI) sensed an electrical arc in the DC (solar panel) wiring. An arc is a genuine fire hazard. Do not simply clear F63 and walk away, and do not keep resetting it. Treat it seriously.

F63 is an arc-fault alarm. The inverter constantly listens to the DC side for the electrical signature of an arc, which usually comes from a loose, corroded or damaged connection in the panel wiring, most often an MC4 connector. Because arcs can start fires, the Sunsynk shuts down and raises F63 deliberately.

What causes an arc fault

  • A loose or poorly crimped DC connector (MC4), the most common cause.
  • Corrosion or water ingress in a connector or junction box.
  • Chafed or damaged DC cable insulation.
  • A burnt or melted connector from an earlier hot joint.

What to do, safely

Important Inspecting and repairing DC panel wiring is a qualified-installer job. PV strings are live whenever there is daylight and cannot be switched off at the panel. The steps below are about doing the safe thing, not about you opening connections.
  1. Look for danger signs. If you can safely see the inverter and DC cabling, check for smoke, a burning smell, or scorch and melt marks. If you find any, shut the system down at the isolators if it is safe to do so and treat it as an emergency.
  2. Do not keep clearing F63. Resetting the alarm without finding the arc simply re-energises a possible fire hazard.
  3. Shut down per your procedure. Turn off the AC breaker and the DC isolator following your installer's shutdown sequence.
  4. Call your installer or a licensed solar electrician. They inspect every DC connector and cable, find and fix the arcing joint, then clear the fault. That is the correct and safe path.

Quick decision flowchart

F63 appears
↓ any smoke, burning smell, or scorch marks?
🔴 Yes → treat as an emergency. Shut down at the isolators if safe, keep clear, get help now.
🟠 No visible signs → still a real fault. Shut down and book your installer to inspect the DC connections.
↓
Do not keep clearing F63 to make it go away. The arc must be found and fixed.
Why we don't give a DIY fix here Unlike a load or cooling code, an arc fault is a fire-safety issue in live DC wiring. The responsible advice is to shut down and get a qualified person to inspect and repair the connections. We won't tell you to open DC connectors yourself.

Related Sunsynk codes

F24, DC insulation failure F08, GFDI relay failure F23, AC leakage current

FAQ

F63 cleared by itself. Am I fine?

Not necessarily. An intermittent arc can come and go with temperature, load and movement. If F63 has shown even once, have the DC connections inspected. An arc that "went away" can return worse.

It only happens on hot, sunny afternoons.

Higher current and thermal expansion at peak sun can make a marginal connection arc. That pattern still points to a connector or cable that needs finding and fixing.

Could it be a false alarm?

AFCI can occasionally nuisance-trip, but never assume that. Treat every F63 as a real arc until a qualified inspection proves the wiring is sound.

Sources

  • Sunsynk Hybrid Inverter User Manual (F63 = ARC fault; check PV module cable connections and clear the fault after inspection).
  • General PV arc-fault (AFCI) safety guidance for DC string wiring.
⚠️ Safety disclaimer. An arc fault is a fire hazard. Solar DC wiring is live in daylight and cannot be switched off at the panels. This guide is educational only and deliberately does not instruct you to open or repair DC connections. Shut the system down per your installer's procedure and call a licensed solar electrician.