"Do not connect a solar input greater than a nominal 48V array for battery charging. Never exceed a Voc of 125V."
That doesn't sound right. How would you charge a 48V bank?
My four 125w panels are connected in series (about 70vdc).
Small gauge wire* is what I use to feed my TS-45 charger for my 48v bank.
Since the total current in my system never over 7 or 8 amps, the losses are minimal.
I have also used the TS-45 with with Four 200W panels (abt 120vdc) 9A max and it worked fine..
The wire I'm using for this test is RG-8 type coax cable.. It works pretty good.
Currently, my 800w array is feeding directly into a hotwater heater..
My 48v bank is only for back-up, so my solar mostly goes to making hotwater..
Our A7 hotwater heat pump ran about 6 hours since April..