I'm intending to add solar to our rig when I get it figured out. Looking to do more than trickle charge my chassis battery. Looking to go off grid completely (and off generator too) for boondocking. A...
To do a full saturation charge takes 16 or more hours. Last time I checked the sun is never up that long.
PWM controllers do not require "big" wire from the panels to the controller and doing so is a waste of materials cost, so the air compressor analogy for that part of the system is not applicable. If it is MPPT then, yes, size matters and voltage drop is important.