MrVolt

From the Manuel... 400A

 
But I will use the 250Amp . (10000va / 48volt = 208.33Amp). I install 125Amp fuses as a rule on my 5kva Units.   

Yes. If it is a single-phase inverter, you can pick what phase it is connected to.
The most basic explanationis this: ESS tries to zero the grid consumption. If you have a three phase meter, a Quattro on L1, and it sees power being exported on L2, it will attempt to import it on L1 to charge the batteries and to get the meter to zero (or limit the PV inverter if you have that setting turned on). It will still do the zeroing over all three phases thing by feeding into/drawing from the grid on L1.
Also, just for full understanding: The Multi/Quattro is always on L1. It doesn't have to be physically on the phase your supplier considers to be L1, what I mean is that from the perspective of the Victron system it always starts counting from L1 (the master is always on L1). If you want to put it on another phase (from the perspective of your wiring/supplier), not a problem. Just keep the right phase rotation (so everything just moves one on).

Let's just look at compatibility when you have the PV-inverter on the input side (cause then I don't have to discuss frequency shifting and all that stuff).
If you want to use the PV-inverter as a part of ESS, and you don't want to feed into the grid, then you must use a Fronius or ABB inverter. The reason it was limited in that manner is because there are inverters out there that appear to support the bits needed for grid limiting, but don't. So it will only explicitly support the ones it knows to work well.
If you are allowed to feed into the grid, then you can use whatever you want. ESS will see  the exported power and attempt to import it to charge batteries.
Then for the second half of the answer: If the PV inverter supports at least the basic mandatory bits of sunspec, the Venus device (aka CCGX or Venus-GX) can read power values directly from it. If the PV-inverter does not support it, then you can install a another carlo gavazzi energy meter and configure it to take the place of the PV inverter (so you can see that data).
So now I get to the brand names. SMA only recently fixed their sunspec implementation. Some missing bits in the older firmware means it simply could not be supported. So they are out. SolarEdge implemented only the most basic bits of sunspec (and rumour has it they are leaving the alliance), so I doubt SolarEdge will ever be supported. Both these brands show up on the venus device, the data is logged to VRM, and as long as you are allowed to feed into the grid it does work with ESS.
 

Most recently made grid-tie inverters can be put on the AC out of a Victron inverter.  Hoymiles micro inverters even have frequency shifting nowadays.
There are a number of standards but I can vouch that if it has the "VDE-4105" standard it seems to work, relatively stable.
The problem is if the Victron inverter is also grid-tied it has no mechanism to control the power output of the grid-tied inverter.
In other words it cannot perform frequency- shifting, so it will export to the grid, without some sort of throttling intervention.
There should also be 5kWh of LA battery for every 1kWh of PV inverter or alternatively  5kWH of Lithium battery for every 1.5kWh of PV inverter.
Also, there is a 1:1 max ratio of PV inverter to Victron inverter rule that should be observed.
What is lesser appreciated is that this downstream PV inverter can still be used to charge batteries as the Victron is a bi-directional device.  PV inverter use far higher dc voltages and so the panels can be a fair distance away without incurring the cost of preventing copper losses.
I use mine downstream of a Phoenix inverter, (the Phoenix has no AC-in), so it regulates by using frequency all day long. I have a small Solis 1.5 and an ABB uno 3kW downstream of it.
They were secondhand, I just plugged them, set up the charger on the Phoenix and they worked.