I emailed and phoned Amazon today about the listing. They said it was a third party listing and shipped from overseas.
All modern electric meters only run forward now. You can't run a common meter backwards. So even if this thing backfeeds the grid you will be paying the electric company to do it.
All modern one-way meters also treat attempts to run backwards as tampering and set a flag. So if you used this and it actually worked, the power company would think you were trying to steal from them and you would get a knock on the door.
It isn't safe to operate this device anyway. It uses a common detachable power cord of the type used on computers. They are not all the same inside. If you pulled a cord from a monitor and tried to feed 550w backwards through it, it might melt and burn down the house. The frequency range this works on is also unsafe. 47 to 60+ Hz is not really okay anywhere. If it misreads the grid frequency and puts power back in at 58Hz there will be interference in your home wiring and maybe your neighbors, too. It should only operate on 50 or 60 and nothing else.
If it's powered up and fails to anti-island when the grid-tie fails, the pins on the back and the cord prongs would be live wires.
And lastly if you have a windmill feeding this, what happens if someone trips over the cord or a breaker blows? Your mill will suddenly go unloaded. That would cause a voltage spike and if the mill didn't furl properly it would overspeed. The setup with a mill is not a simple plug and play like the ad says. Solar panels connected to a charge controller have to be tied to a battery bank, too, or the voltage spike from the panels can fry the controller if it suddenly drops off line.
