Load side AC coupling, SA 15K and 18Kpv

[Ampster]

But still no definitive answers from Signature/EG4 to either of my questions.

I look at it from two perspectives. Theorectically the only limit on AC coupling when the grid is up is the throughput capacity of the Inverter. When the grid is down the limit on AC coupling becomes an issue that involves battery pack size and the grid forming inverter firmware's ability to use frequency Watt to control the AC coupled GT inverters.
There is also a scenario which some call AC coupling but in which the grid dependant inverter is not actually coupled through the grid forming inverter and is connected directly to the main service panel. Clearly in this scenario there is no functionality when the grid is down but the only limit on AC capacity is the utility infrastructure to handle backfeed.
So depending on the scenario, the answer to your question will be different. Based on the title of this thread, the load side AC coupling assumes the grid dependant inverters is connected through the grid forming inverter, shich is presumably the load side.

 

[Luxpower_Gilbert]

No. As mentioned in the first post, there would be 35-40 KW of PV. The question is whether the 18kpv inverter supports additional power via AC coupling on the load side. And if so, how much in a parallel configuration.

LXP recommend connecting ac couple to the Gen Port, max is (90A ac)...