He could switch out the 800amp main for a 600amp main if the building load calculation was under 600amps. Then he would be only 40amps out of compliance to the 120% rule.
600 + 400 = 1000amps of breakers...
800amp bus rating x 120% = 960amps...
1000amps - 960amps = 40amp difference....
For 2014 we will use the inverter output rating x 125% for the backfeed value to use instead of the PV breaker rating...
So if that job had a 240KW inverter it would be 240KW divided by 831= 361amps
361 + 600 = 961
