I've completed a beautifully (inspector approved) installation of a new 200 amp service panel to my home (upgraded from 100 amp). I have now strung a 0/0 underground aluminum cable in sched. 80 conduit from my barn to the main panel to connect a sub-panel in my barn to this new 200 amp panel.

How do I connect this rather large wire to the service panel? The heavy wire is too large for the existing neutral/ground bar. I assume there are breakers specifically for large wire like this? Are there lugs that can be installed on the neutral/ground bar for large wire?

Also, would it be feasible to run the large cable to a cut-off panel before going to the main panel, and then running smaller copper (#3) to the main panel?