The 2011 NEC 705.12(A) for supply side interconnections limits the inverter overcurrent protection to the rating of the service from the utility. As an example, if the service is 400A then your inverter AC overcurrent protection is limited to 400A. This will limit the inverter output to 400/1.25 = 320A and the inverter power rating at 480V 3ph to 266kW. If you have a load side interconnection then your output will be limited by the existing service entrance overcurrent protection, which in this example would also be 400A.
If you are still on the 2008 NEC I would still go by these limits.