I have run my current trailers solar wiring down the fridge vent to the charge controller then into the 12v side of the control center. My previous trailer was direct to the batteries.
To compare the two trailers fairly, I used the same system on both trailers (260 watt with a 20Amp controller). I can't say that I really notice any difference in charging abilities even with the longer run of wire on the new one.
I know there will be some loss due to the length of wire, but in my case there is just not enough gain to be had to warrant a rewire direct to the batteries.
