Normally the higher voltage/less amperage should be the longest set of wires.
If you look at the power grid run into neighborhoods and business you'll see high power (small) wires that run into transformers, and from there heavier wires low voltage that runs into the buildings.
Amps are like water
running through pipes. The more amps (water), the bigger the wire (pipe) needs to be.
So, when you kick up the amps to charge the batteries you'll want larger wires. This is why some go to 24 & 36 volt solar panels
, to make longer runs on smaller wire.
Plus, you'll want to get your MPPT
out of the humidity/weather but yet give it cooling