In my arctic fox there is the same thing, which was pre-wired with solar from the factory. The plugin was an SAE 2 pin connector, bought one of these in 8gauge for about $4
SAE 2 Connector and just cut the end off i needed and plugged her in and attached 8gauge wire from it to the solar panel.
You will need to find out where the other end of that pre-installed connection goes as thats where you will need to put your solar controller and it should also have the pos/neg wire that also goes to your campers battery. In my arctic fox the location of the wires was in the wall next to all the other monitors/switches and was clearly labeled "pre-installed solar wiring location"
Good luck, have a look around for a pos/neg wire inside your battery compartment, and also maybe under your sink or some other area which a solar controller may be mounted. Or ask lance directly or maybe a lance owner will chime in.
Makes the installation extremely easy, my install took me about 1hr to install the panel and controller since all wire was already in place. All i had to do was screw panel to roof and cut out hole in wall to mount controller.
2015 Nash 25C bumper pull /w 300watts solar
my installMy Truck & RV youtube channel 2005 F-350 Diesel 4x4 CC SB SRW
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12ft Lund WC boat & 9.9 Yamaha 4 stroke on custom loader.