Grid tie inverters will not run without the grid being present. I am not even sure they have the 60hz time base to make power without the grid (they use the grid to pace the inverter?). I assumed that was why they wouldn't put out.
This is the impression I got from the people trying to sell me a system anyway. I did want off grid generation in an outage and they said not with a grid tie inverter.
This is one of those things I would fall back to the manufacturer's instructions on. They know what their box is supposed to be able to do.
I am not sure if this is part of the listing standard.
