PV trigger, possibly ?
To make sure it does not trigger on a MPPT sweep or something short lived, just make the Aux 1 PV Trigger attack time/ delay time (whatever it's called ?) to be longer than a few seconds. Maybe even a couple of minutes ?
And the HOLD time to be a couple minutes also.
Set the voltage lower than you would ever expect it to go. Lower than what you normally see it go anyway. Maybe 20 volts ?
See if that works OK.
This in addition to what Larry is suggesting.
boB