Question on victron MPPT solar controller

[Centex]

Originally Posted by NEWYORKHILLBILLY

Good point. I up sized my controller to 50 amp because I wanted to be able To plug in my 100 watt portable into the same controller as the roof panels . would I size this ground wire for 50 amp or the max short circuits amps of all my panels combined

Personally I'd size both the (+) output wire and the ground wire to the rated output of the controller - then I'm one-and-done no matter what changes/additions (within the spec limits of the controller) I may make on the PV input-side in the future.

EDIT - I just noted that some controllers (e.g. Victron SmartSolar MPPT TR 150|45) allow a higher total Max PV short circuit current (50A) on the input-side than it's rated max battery current (45A) on the output-side. In that case I'd go with the higher of the two for the ground wire sizing calculation in keeping with my preference for conservative 'fail-safe' approaches (though that probably won't manifest as a larger wire gauge). So, you might check your specific controller documentation just to 'be safe'.