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 space.