Nope. Let's say L1 has 200 A of 120 V load circuits (10 x 20 A circuits, for example, not very different than what is the service panel of my old house), and a 100 A main breaker (we agree that it is typical for the sum of load breakers to exceed the main breaker). With a single source, we know that even in an overload condition, the 100 A main will trip.
Now let's add 100 A of PV to the opposite end of that bus because we think 120% is conservative and 200% sounds better. It would be *possible* for 200 A of load on L1 to be supplied (100 A from main, 100 A from PV) and no breakers tripped. All 200 A of that current would potentially travel to the transfomer through the neutral bus (which also has 100 A rating), neutral lug, neutral service feed and service drop (which have been sized, like the service panel, only for 100 A service), where 100 A could then return to the inverter on L2. Yes, L2 loads would reduce the neutral current, but there is nothing that requires L1 and L2 loads to be balanced, or for L2 loads to even be present if the load center was poorly arranged.
Now let's add 100 A of PV to the opposite end of that bus because we think 120% is conservative and 200% sounds better. It would be *possible* for 200 A of load on L1 to be supplied (100 A from main, 100 A from PV) and no breakers tripped. All 200 A of that current would potentially travel to the transfomer through the neutral bus (which also has 100 A rating), neutral lug, neutral service feed and service drop (which have been sized, like the service panel, only for 100 A service), where 100 A could then return to the inverter on L2. Yes, L2 loads would reduce the neutral current, but there is nothing that requires L1 and L2 loads to be balanced, or for L2 loads to even be present if the load center was poorly arranged.
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