[jedberg]

It depends on how your system is hooked up. Some will cut out when the line power drops off, as a way of protecting line workers who might be working on what they think is a unenergized line, so they aren't surprised by the power your system puts on the line.

Others are designed with an automatic shunt that will still allow you to draw power as long as you are generating it.

And some require you to manually flip a switch.