This feature requires the newer RV GS series inveter and it must be wired into your A/C controller to send voltage to the inverter when cold is called for.
The older RV X series inverters do not have this feature.The GS inverter manual has the information.
I have a vast knowledge about PV solar, batteries and inverters. I'll try to provide the best answer if I know it and hopefully correct some "Campfire" talk.
Full-time 1999-2004. Part time now. '92 Hawkins, 360AH Lithium Battery, 1480 Watts PV solar.