Well, small grid tied inverters generally don't because they assume that you are doing grid-tied only stuff, that
is you would not expect to run your whole house on this inverter if the utility line went down because this is too
small to support the total household load. But this is a bad precedent to set for larger inverters.

The other hand I would insist that a 7KW or more grid tied inverter have a stand alone mode
so that in event of a power failure your house could stand alone and run on it's back up battery
bank. The grid connection will be severed in any event. It should cost only a few dollars more
to have the frequency generating circuit added.

Not doing (b) will penilize people who are grid independent and want to use that type inverter, and would
prevent you or someone else from becoming grid independent should they want to in the future. I predict
that grid interconnect benefits are joing to go the way of a July snowstorm in the Northern Hemisphere once
electrical utilites find out what they are up against.

:S:MarkSCoffman