Grid forming inverters are for solar generating plants. They are allowed to start up an unenergized grid. At that level they are a part of the utility grid.

For homes to run of of solar when the grid is down you need to do islanding. This is a seperate beaker box feed directly by the solar and battery. This allows the house or a portion of it to stayed powered without putting power back to the grid and endangering any linemen working on the grid.