Also in the US regular 120v outlets are fed from 1 of 2 transformer legs. If you back fed power through a 120v outlet, roughly half of the circuits in your home would function and the others would be dead.
And disclaimer: no one should do this, but when the transfer switch disconnects from the grid, would it work to jump say a breaker across the L1-L2 hots to share that 120v backfeed over both?
Clearly the 240v appliances won't work in this configuration, but the fridge on one leg and the internet on the other will still work ok, right?
Again, no one try this - it's just a thought exercise.
Yes, it will actually work. I know it's very much not to code, but when we lost power for over 10 days, I did this to keep our furnace running and us from freezing to death since it was -10F out.
I only have a small 120V generator, but hooked both legs to hot and backfed via our EV charger's outlet, since its a 50A circuit. Like you said, nothing 240V worked, but that little 3kW generator did a great job powering basically the whole house with no issues.
That winter was definitely a big driver for me to get a backup battery system so our solar could power the house.
According to the article this system also detects power outages and shuts off when they happen. Just like full-scale solar power systems. But yeah, no physical kill switch.
That's great, but it doesn't matter unless it has the physical cutoff that's required to bring that kind of system up to the current electrical code for such a system.
Physical shutoff via relays is required by the standard. We've just been through a scandal where a manufacturer skimped out on putting them in and had to recall the devices.