@BalooUriza
I might be entirely wrong but as I understand it they have pretty sophisticated current leakage and monitoring abilities and very very quick shut-off. So yes it's back feed but it can detect if something anomalous has happened so it locks out if a breaker is tripped or if a line is cut.
I don't believe you can use these in an outage situation, and you're correct it would be unsafe without an interlock.
@f4grx @balkonsolar