Plug-in solar
Maryland recently legalized plug-in solar. Max 1,200W, has to be cord-and-plug into a "standard outlet" with no interconnection agreement. So the microinverter is 120V and lands on a single-pole breaker, meaning it only injects onto one leg, L1 or L2 depending on which slot the breaker takes.
I've got a 200A split-phase service. Central AC is 240V, everything else is 120V spread across both legs.
My question: if the inverter is dumping 10A onto L1, and at that moment my load is mostly on L2, does that power actually get used? Or am I only offsetting whatever happens to be on the leg I'm injecting into?
My understanding is that it works fine, because:
- L1 and L2 are just the two ends of one transformer.
- 240V loads are wired line-to-line, so injected current on L1 flows straight through the AC compressor and out on L2. Never touches the transformer.
- The meter reads both legs and sums them, so net import drops by whatever I generated regardless of where it entered.
Conclusion I'm working from: one 120V circuit on one leg offsets whole-house consumption, and there's no reason to try splitting injection across both legs.
Am I right? And is there any second-order reason to care about leg balance? If not, that would mean that a 240v plug in system may be able to cover both legs?