If your unit was 'prewired for solar' there should be a sticker somewhere inside on the wall saying wires for solar behind this panel. If so, in that wall there will be 2 red, capped, 1 with a + on it. The one with the + is connected to the battery. The other goes to the connection on the roof. The black wire is just looped. You have to cut it and check to see which end goes to the ground side of battery. The other goes to the roof. This is where (although some put the controller as close to the battery as possible) you wire and install the controller. If the unit is prepped for solar, the connection point is on the roof and after installing you panel or panels, it's a simple plug in connection. All in all took me a little less than 2 hours to get it all done.
2019 Jayco 317RLOK
2018 Ford F-250 Platinum