I set up a SI based system this year, made out of a DC Solar trailer.
Here are some pictures of the system. AC coupled Enphase micro inverters, and some DC CC panels.
A question I have, for anyone with a grid tied or backup system that's integrated with your house, either wired in or plug in as needed: How do you have the neutral - ground bonding set up? The house has the neutral and ground bonded at the service entrance. If you are running the Sunny Islands only off grid not connected to the house, you would probably have the neutral and ground bonded near the SIs. A system is not supposed to have more than one path between N & G, and typically would be located at the main source of power, ie the service entrance or the SIs.
In my case, the SIs are in the garage about 120 feet from the main electric service at opposite end of the house. Once I started backfeeding the house panels, I attempted to use only the N-G bond at the service entrance, thinking that's the correct way. This created some voltage transients or spikes, and took out a couple items in the house: the fridge fan MOV & fuse, a kitchen clock radio, several internet device wall warts (Daddy broke the internet).
That event may have been a combination of things: 1) I've found that the freezers in basement, and likely the fridge, return some current on ground during compressor startup. Doesn't seem right, but from what I read, that may be common. 2) That first time, I was using a relative light wire to feed about 60 from the SIs back to the main panel in basement, a #12 4 wire cable & 20a breakers on each end. 3) A couple other circuits in the house did have faults from neutral to ground, typically not an issue and you'd never notice until trying to add a GFCI, but I checked carefully and fixed a couple as I moved circuits to the new basement critical loads panel. After fixing those faults, I typically did not see current returning on ground to the SIs any longer. Still do see it when the freezers start up though.
I put the N-G bond back at the SIs AC1 distribution panel. Everything worked fine, even with just the skinny #12 and managing loads to not trip the 20a. I then properly redid the basement panels, and have AC1 & AC2 linked with 50a breakers and #6 copper. The L1 & L2 for most all the house are fed by the SIs, a couple items L1 & L2 still on the utility in the basement grid panel, N & G are all connected together from service entrance through all the panels. If there's not quite enough sun, the SIs are set to connect on AC2 to charge if SOC is lower.
Everything is effectively done, and I think it should work with only the N-G at the service entrance. I'm gunshy to remove the N-G bond at the SIs, for fear of another Daddy playing lightning in the garage, resulting in Daddy fixing all the appliances again.
I'm concerned that without the (incorrect) N-G bond at the SIs, the transient ground current from the freezers will have to go all the way out to the service N-G bond, then on N from there all the way back to the garage.