I have three Powerwall 2s. Each one can supply 5kW, and the three in parallel can provide 15kW. Obviously if I'm drawing more than 5kW, at least two Powerwalls will be supplying power. But if I'm using 3kW, does one Powerwall supply 3kW while the other two are idle, or does each Powerwall contribute 1kW? If they're always sharing equally, do they ever switch to just one for efficiency's sake (say I'm on vacation and the house is using less than 100W)?