[NiHaoMike]

Basically, the inverter plugs into the existing breaker box via a 240V outlet with a dedicated breaker. It then powers loads on that breaker box but not backfeed the grid, which is done using sensors installed inside the breaker box to detect the current from the grid. Thus far, I'm only aware of Sol-Ark having that feature.

It's also worth mentioning that the reviewer of the XW has reconfigured his system to run in off grid mode most of the time, since with an unbalanced load, that could cause an export condition on one of the phases in "zero export" grid tie mode! (For example, put 2kW of load on one phase and since it is only capable of sourcing to both phases at once, it will source 1kW to each phase, with one phase exporting 1kW to the grid and the other phase importing 1kW from the grid.) The design I'm working on will be able to adjust the phase currents independently, avoiding that problem.