Yes
I drilled a 1.5 m earth spike into the ground with a big hammer outside the house and ground the inverter to it.
Later I tested a 2 pole 10 amp relay and put the same ground on one N/C contact and on the com side, the neutral of the backup side of inverter.
The N/O contact is wired to the N bar after main CB.
The coil of the relay is been wired to the grid L&N after main CB, so when grid fails, relay de-energized, backup N is linked to new earth,93v floating is gone.
May this be safe enough?
Comment please!!!