Re: Microinverters and Anti-Islanding - how does it work? Technically?
I think it's more complicated than this. The voltage follow the sine wave, so it rises from 0 ro 339, then falls back again and goes negative. You don't get a single voltage, but rather the whole set of voltages from 0 to 339. If GT inverter has 3kW array and voltage is only 10V, it would be pushing out 300A. That would produce a really bad power factor. If it doesn't push this current, it has to store the energy somewhere and then push it out when voltage is higher. It also needs to watch for the polarity because it changes 120 times per second and it needs to push out current of the correct polarity. So, it has to be some fair amout of voltage monitoring and some mechanisms for time-shifting the energy to produce good power factor.
When grid power goes off, the voltage will drop because the inverter(s) cannot power the whole grid. Inverter may detect this and shut off.
Off-grid: 6.12kW SolarWorld, 8 Trojan IND13-6V, XW6048, 2 XW MPPT60-150, 10kW Generac, 5kW Champion