The OP says his inverter has the same shut off at 15v as mine does.
"It doesn't take winter conditions to be cool but sunny. This past weekend while camping it barely made it into the low 70's for a high and morning temps were in the 40's. Temp compensation begins to increase voltage below 77 degrees F. My inverter says its high voltage shut off is 15V as well. I am a little annoyed that it trips at 14.8ish, but it is a cheapo inverter off ebay so I can expect to get what I paid for. I've been driving the setpoint down even further because I'm trying to find a sweet spot where the quick spikes from dropping load on the inverter don't get high enough to fault the inverter. It is the spikes causing the faults, not steady state operation."
He has cranked his controller set point way down, and still gets this problem, I never see with temp comp and 14.6v controller.
IMO the only thing left is voltage drop due to some sort of wiring/connection issue the OP has where the inverter is "seeing" voltage higher than it really is
