Hi Folks,
I have a 3611RL on order, I talked to the Montana Rep about the Solar prep, it is a marketing gimmick. The wire goes to the Convenience Center, and is for hooking up portable panels, in the 100-300 Watt range.
It is the black plug at the top of the Convenience Center in the picture below (looks like 12 or 14 gauage from the picture).