I think it was Stephen Fahey (Sparweb) who posted a link to the NEC guidelines for solar installations. I printed it out and have it at home, but don't have it handy at the moment. If you were to use 2/0 wire for the battery interconnects, then I think you would be required to fuse them accordingly as well. I would likely opt for 4/0 all the way even though it is a pain to work with and the costs are significantly more. That way I could just fuse the positive ends of cables from the bank to the inverter with a fuse rated for up to 4/0, about 250 Amps which should be fine for exposed THHN copper cable, and have a breaker at the DR3624 of about a 175 to 200 amps at the inverter, although I would definitely double check all of this before I did so. I would also fuse any other cables from the battery bank at a rating appropriate for the cables size. Rich