Re: Yet another Solar installation thread - comments/advice requested on install spec
10 awg is pretty small for a long run. I would go heavier. You want the highest voltage you can get at the controller. I would use 8 awg at a minimum.
From the controller to the batteries is even more critical - you want the voltage at the controller to have as close to zero drop at the batteries as possible. The controller should use heavier wires to the batteries and be as close to them as possible without being in the same compartment - aim for 2 or 3 ft and use 6 awg or 4 awg to minimize loss.
Living aboard in Victoria Harbour