MuKi

Would also recommend to make sure that the breaker and wires are sized correctly. And circuits are identified properly. i.e. if you switch a light circuit off that only lights and not plugs go off, I had both these problems when COC was done on my new place.
If COC done recently, then you should be good to go. 

Right at the bottom of the list in the footnotes...

In this scenario i feel it would logical to have an changeover switch as the inverter would be able to backfeed into the grid as it does not know the difference. 
The setups I have seen all have the grid connected to the inverter and the output of the inverter connected to load, so no chance of the inverter feeding back onto the grid. 

Electro Mechanica.