Can I clear the arc fault myself?

No. On SMA inverters, resetting after an arc detection is a confirmation that any damage to the panels, cables or plugs has been repaired. Clearing it without an inspection removes the message but leaves whatever caused the arc in place.

My inverter restarted by itself after an arc before. Why not now?

On newer Sunny Boy -US models the AFCI can be set to stop after every arc, to interrupt briefly and resume, or to stop only after more than five arcs within 24 hours. If your inverter has now stopped, it has reached the point where it needs a manual restart, which should follow an inspection.

The display also shows event 8206. Is that a second problem?

Not necessarily. SMA uses event 8206 for the same arc detection when the inverter is waiting for someone to confirm the damage has been repaired. The two can appear together, and both point to the same inspection of the panels and DC wiring.

SMA event 4301 electric arc detected: what it means and what to do

SMA event 4301 means the inverter's arc-fault circuit interrupter (AFCI) has detected an electric arc in the solar (DC) wiring and has stopped feeding power. Older Sunny Boy TL-US models show "Electr. arc detected" with "Check generator"; newer -US models show "Serial el.arc in String ... detected by AFCI mod.", often naming the affected string. SMA treats the fix as work for a qualified person: the system is shut down and the panels, cables and connections are checked for damage. Leave the system as it is and book a technician.

Safety: act now

Common causes

A damaged solar panel somewhere in the array. SMA lists defective PV modules among the things to repair or replace.
Damaged DC cabling or a poor connector between the panels and the inverter.
A faulty DC connection inside the inverter itself, which SMA also tells technicians to check.

Safe steps to try

Leave the system exactly as it is Do not try to reset or restart the inverter. SMA states that a tripped AFCI can only be reset manually, and resetting it is meant to happen after the damage has been found and repaired. Do not open the inverter, a disconnect, a junction box or any conduit, and do not touch the panels, racking or wiring.
Write down the full message Note the event number and the text on the display, including the string letter if one is shown. If the display says "String N/A", SMA explains that the arc could not be assigned to one string, so every string has to be checked. A photo of the display taken from a normal standing position is ideal.
Note anything unusual you can see from the ground If you can see the panels from the ground, note any obvious damage, fallen branches or signs of animals around the array. Do not climb onto the roof.
Book a technician SMA marks the corrective steps for this event as a job for a qualified person: disconnecting the inverter from all voltage sources, inspecting the modules and cabling in the affected string, and repairing what is damaged before the inverter is restarted.

When to call a professional

Call as soon as you see event 4301. An electric arc is a fire risk, SMA reserves the inspection and repair for qualified people, and the inverter will not produce power until the cause is found and the arc fault is reset.

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Frequently asked questions

Can I clear the arc fault myself?: No. On SMA inverters, resetting after an arc detection is a confirmation that any damage to the panels, cables or plugs has been repaired. Clearing it without an inspection removes the message but leaves whatever caused the arc in place.
My inverter restarted by itself after an arc before. Why not now?: On newer Sunny Boy -US models the AFCI can be set to stop after every arc, to interrupt briefly and resume, or to stop only after more than five arcs within 24 hours. If your inverter has now stopped, it has reached the point where it needs a manual restart, which should follow an inspection.
The display also shows event 8206. Is that a second problem?: Not necessarily. SMA uses event 8206 for the same arc detection when the inverter is waiting for someone to confirm the damage has been repaired. The two can appear together, and both point to the same inspection of the panels and DC wiring.