I see what you mean. Using a balanced load does the trick.
The Parallel load on the top rail
perfectly matches the load on the bottom the load on the bottom rail.
So, the two rail loads, both being of the same resistance, act as a voltage divider across the 240, with a perfect 120v on each rail.
Causing zero current flow in the Neutral..
In my
imperfect world, my wife is going to turn off one (or more) of those 100 watt lamps.
That would increase the resistance of the bottom rail, upsetting the balance.
Then there is going to be flow in the neutral.. Right??
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Humm, If the guys who designed the mini-inverter added a voltage level control on each rail.
And then, used a current sensor in each hot line, to sense any imbalance in current flow.?.
They would be able to compensate for the imbalance by boosting the voltage on one rail,
until there was no more current on Neutral!
Hey! Perhaps that's how they are able to dump the full 200W onto an unbalanced grid!!