Run the L1, L2, N, and G from the 6kxp to the service panel.
You will have to check if the 6kxp takes care of the N/G bonding. This should be the default, but you never know. If not, then you will need to do it in the panel.
The service panel can be a main lug type, as there's already a...
Not sure if you realize that you posted in the wrong section.
This one is for solar panels. You want.......
https://diysolarforum.com/forums/batteries-for-sale.40/