The built-in AFCI complies with UL1699B-2018. This is currently the only existing standard. As new standards are issued, we expect our inverters can meet any new requirements with a firmware upgrade.

The maximum length specified in UL for reliably detecting arc-faults is 60 metres. This translates to a maximum distance of inverter to the start of the string of 35m when using 24 module strings.

We recognize that this length is not sufficient for commercial projects and will update our guidance when a more relevant standard can be tested to.

The following is according to the UL standard;

• • When an arc fault is detected, the inverter will send an alarm and shut down for 5 minutes. After 5 minutes the inverter will attempt to restart. Alarm is “Arc Fault Detection”
  • If more than 5 arc faults are detected within a 24 hour period, the inverter will shut down and will require a manual reset before the inverter restarts again. This reset can not be completed remotely. A technician must visit the site and inspect all the connections before clearing the alarm.

If an arc fault is detected the entire inverter will shut down.

Yes, arc fault detection is actually off by default when the inverter is shipped. IT can be switched on or off in the inverter settings.

Manual On Site Change

On the Inverter LCD navigate to;

• Advanced Settings
  • Special Settings
    • AFCI Set

Remotely Change Setting

If the inverter is equiped with a monitoring device capable of digital O&M the setting can be changed remotely. See Remotely Change Inverter Settings

It now only defines arc detection in line.  That would cover typically errors due to bad connections from MC-4 connectors which probably are the major source of problems. Between + to ground or – to ground or + and – , the current will not go through the inverter and inverter will not be able to detect the arc. Whether IEC or another body would demand that they will be detectable as well, is open for fierce debates.

Please note that inverters are shipped with AFCI Off.

• OX and XLX-MII Series: All inverters
• UX Series: Inverters with “SA” at end of product code. i.e. S2.UX60000SA
• SX, MX, LD, LQ Series:
  • If item code ends in .2, then AFCI is present
  • If item code ends in .1, then a firmware upgrade will be required before AFCI can be activated.

There is no guarantee that inverter shut-down will extinguish the arc. The modules will continue to have voltage as long as there is sufficient irradiance, the flame won’t be extinguished with certainty unless there is also module level rapid shutdown (MLRS) to reduce the module voltage.

Yes. Our inverters are compatible with the Tigo module level rapid shutdown solutions.

Full deployment of optimizers together with the use of a CCA-KIT are required.

The rapid shutdown is activated by AC power loss.