I will post here the answer of SS once i got it for sure. Meanwhile and in order to be understandable by the basic human being i am....here are the basic questions i still try to find a clear answer...if any expert could light my path...i would be happy !

Each time a 10 kwh array is AC coupled to the 18 k and a 18 kwh array is directly connected to the 18 k MPPT with 60 kwh of batteries.

Case 1 : Grid export is permitted.

Grid is ON, total load is 15 kwh, ac coupled array is giving 3 kwh, 18k array is giving 5 kwh and batteries are dead or at SOC that does not permit any power draw. What happen ? Does the 18k can draw power from the grid in grid assist kind of mode ?

Grid if DOWN,

total load is 15 kwh, ac coupled array is giving 3 kwh, 18k array is giving 5 kwh and batteries are at 90% SOC. What happen ?

Does the total power able to being draw is equal to 12 kwh inverted from the 18 K + the AC coupled array power given a the same time or does it can not be added to this ?

Case 2 : Grid export is NOT permitted.

Grid is ON, total load is 8 kwh, AC coupled array is giving 7 kwh, 18k array 15 kw what is happening ?

If load is 6 kwh, AC couple array is giving 1 kwh, 18 k array 3 kwh and batteries are dead, does the grid assist works ?

This is confusing because the system works in Millsan1 config as i was thinking it should be even if he did not tried bigger loads than 12 kw to see what happen and at the same time SS guys are telling me it can not work like this. I am lost

Be sure i will post SS answer here asap i get it....

Case 1 - On- Yes, you can draw from the grid, up to 200 Amps

Case 1 - Down- You are at max, since AC Couple is only giving 3. 3+12 from 18 = 15, so you are OK.

Case 2 - 8kw- Load is fed, excess goes to batteries. When batteries get to a set point you control, the AC Couple will be ramped down. In my case I have it set to 95% SOC. When batteries reach 95% SOC, AC Couple will be turned off via frequency shifting. When batteries reach 100%, solar will feed your loads, there is no excess, as loads pull power, solar does not push power.

Case 2 - 6KW - Yes, you can pull from the grid up to 200 amps.

Long story short, the only practical limitation is the 12 KW inverting from the 18K, in an grid down situation. But that is a lot of juice, and if it is during the day, you can still get more from the AC Coupled system.

On grid, there is really no meaningful limit. Same deal, 18 can only invert 12K, but AC Couple can provide up to an additional 21 and the grid can provide 200 Amps.

I understand your concerns, but please understand that the info given my the EG4 person was slightly inaccurate and needlessly confusing.