Battery charging with alternator and solar simultaneously

[DX grunt]

You usually won't get both to charge all the time while driving.

Depending on the the Solar reg settings it will 'see' the Alternator voltage of 13.8 or more and think the battery is fully charged so should spend most of the time in float not bulk charge.
The Aux will usually accept most of its charge from the Alternator source, cable voltage drops etc aside.

If all components are OK it won't cause any problems

@the evil twin

You learn something every day.

I leave my solar plugged in 24/7...… sort of set and forget system. PML.