Connecting 100A service to barn
I'm getting ready to electrify my barn. It's about 500 feet from the existing breaker panel in my house, and I need roughly 80 Amps of capacity. I have a 500 foot spool of 4/0-4/0-2/0 aluminum service entrance cable, which should easily handle my current requirements without an excessive voltage drop. My basic plan is to put an 80 or 100 amp breaker in my existing panel, run a line from there underground to the barn, and tie it into a subpanel.
If the subpanel were only a few feet away from the main panel, I'd use 3- or 4-gauge copper wire and be done with it. However, since my wire is so vastly oversized, I have serious doubts that it would physically fit into a 100 amp breaker. Plus, I'm unsure whether it's allowable or advisable to run aluminum wire directly into a breaker in my main panel. Should I instead mount some sort of disconnect or stand-alone breaker box on the outside of the house that makes the transition from copper to aluminum? On the other end of the line where it ties into the barn, can I simply sink a new ground rod into the earth and hook it into the sub-panel just as if I was installing a main panel from the meter box?
Sorry for the multiple questions, but I figured it was better to get them all out at once. Thanks for any advice.