Is there a sticker inside on a wall showing location of wires?
We have a 19 Jay Feather and the bedroom wall had the sticker. It shows the location to install the solar controller.
If it does not have that sticker, as some people tend to pull it, then I would suggest contacting Jayco Customer service:
https://www.jayco.com/owners/owners-support/
You will need to include your VIN# in the request.
Ask them to either send you the wiring schematic or if they know the location of the solar wires.
Check up on the roof also, to see if there is the connection point for roof panels.
Are trailer already had the connections up on the roof and many of the Jayco's do.