Solar panels feed a controller first , which monitors and manages the output charge to the battery array.
The plugs on the roof feed down to the power room, but need a controller.
You can add multiple solar panels to the roof, typically in parrellel ( plug adaptors to expand )
The wattage of each pannel, added together when in parrellel, will define the size of the controller you need.
Lots of great stuff here on JOF about solar, including a social group about solar stuff.
I have some picture on my profile of my solar setup
Jim & Kim from Colorado
2014 Eagle 30.5 RLS
2015 Dodge 3500HD SRW 6.7L
Click on my profile for Mods and notes