Wire/fuse size for 24v solar

[Elmix]

I’ve read a bunch of posts and watched a ton of YT videos but still confused. Here is what I have:
3*350W panels, 150/45 MPPT Victron charge controller, 4*100Ah BattleBorn batteries connected in series, 24/3000 MultiPlus Victron Inverter/Charger, 40A DC to DC converter. Distance from the panels to charge controller 6 ft, between the batteries and inverter 1,5 ft. I assumed I can size down the wires because of the lower current, but most of the videos/blueprints show 4/0 wire for the inverter and the Victron manual recommends using 300A DC fuse. What am I missing?

[JDOnTheGo]

Assuming "BattleBorn batteries" are 6VDC each, doesn't sound like you've missed anything but I'm not sure I understand the question. The subject seems to be asking about wiring the solar panels but the body seems to be asking about battery to inverter wiring.

If the former, what is the output voltage of the panels?

If the latter and assuming your battery bank is 24VDC, you probably could use a smaller gauge cable from battery to inverter. A glance at the charts indicates that possibly as small as 2 gauge - even considering the peak output of 6000 watts. You might also want to take a peak at the connectors on the inverter so see what size cable will work best - their recommendation could possibly be related to that.