I think you mean a solar charge controller. These if installed as part of the solar prewiring done on newer models should be somewhere near the main control panel. It should say solar controller or something similar.
The roof should have a "port" on the roof, a place to connect wires from the solar panels. From the port there are wires inside that run to the solar controller.
If your coach was prepped for solar, you should see something that looks like this on your roof...
Some of the newer coaches will also have the controller already installed. My previsous coach (2018 Outlaw 29H) was solar prepped and only had the roof connector and the wires run down to the electronics bay. I installed a solar converter and panels.
My 2020 Magnitude came with the roof connector and a solar controller so I only needed to add the panels.