I’m a little wary of plug-in solar in the US. Some of the bills propose allowing 1200 watt panels which can overload wiring depending on what else is on the circuit and how in the wall wiring is run. Limiting plug-in panel wattage to, say, 400 watts might be necessary
Back feeding power is always problematic. A proper system should detect and match the mains before providing power. Once they become normalised then lower quality kit will start hitting the market.
The problem comes when they have to do line work etc. The power is intended to only flow 1 way, so turning it off, and making it safe is easy. It only takes 1 dodgy plug in solar to deliver a lethal shock to someone working on the line. Even worse, it could suddenly appear either by being plugged in, or the sun coming out, so a tested safe line can suddenly become hot.
It’s worth noting that fixed solar can also have this issue. However, it’s a lot easier to regulate and enforce with fixed installs.
How do other countries handle this problem? Like China or countries in Europe?
I have a friend who works for the UK grid. He visibly winced when I mentioned the plug in back feeding systems a while back. They’ve had a few close calls with “off grid” setups being used on grid.
Apparently even properly installed solar is a serious problem, though that’s more down to the sudden demand shifts it creates. It throws off their predictions and threatens grid stability at times.
I’m a big fan of solar, at all scales, btw. We just need to remember that the grid is not just a dumb system, it has a lot of active parts that were never designed or intended for use with microgeneration.