Hello neighbor, I started with a small, leased Solar City grid-tie DC string system and then added another 3kW Enphase system. Couple of years later added a Schneider XW+ 6848 & batteries, whole house back up, AC coupled to the existing grid-tie systems. One of the batteries is a DIY build. In the process of adding all of the above I replaced the original 100A main panel with a 200A panel, 42 spaces. Cannot comment regarding the permitting process if you know what I mean.
In one sense its a bit of a "Franken" system but actually works quite well with no problems so far.