After seeing a few videos by a local electrician, explaining TN-S and TN-C-S earthing systems, I think that common Neutral is the best way to go.
It solves many problems and is simple.
If I understood correctly, even earthing systems that have a PEN connection coming from the grid supplier (power company), may benefit from this, as they are usually earthed again at the premises. So even if the PEN from grid gets cut at the power lines, you still benefit from the local N-G bonding.
Having said that, you need to check to make sure my assumption above is correct.
And, unless your Neutral is bonded in your consumer unit (A.K.A DB- distribution board) , you need to connect the inverter BEFORE the main RCD. That's because if the main RCD opens, you loose the Neutral connection altogether. At least that's how they wire up things here (Middle-East):
Main MCB (phase/or multiple phases) -> Main RCD (here is where the Neutral comes in) -> Circuit MCBs.
Of course it would be wise to add an RCD on the output of the inverter.
The only thing I'm concerned of, which really doesn't have to do with common Neutral is blinding of the Main RCD by some sort of DC leakage.
This could happen regardless of if the inverter is connected before or after the Main RCD, I suppose.
But I haven't seen anyone address this in regards to inverters.
There are some YT videos explaining what RCD blinding is and how even small DC currents could cause it.
As I understand, most of the HF inverters we are talking about here are Non-isolated, so there is a risk of DC leakage on to the AC input. Either from battery or PV.
