I have this kind of system too, but when I wanted to get solar for the other side of our roof after our neighbors took down a tree I learned that they're no lon

I have this kind of system too, but when I wanted to get solar for the other side of our roof after our neighbors took down a tree I learned that they're no longer allowed in MA for new installs. Starting with the 2014 National Electrical Code (NEC) you need to have some form of rapid shutdown to protect firefighters in an emergency, and in the 2017 revision it got much stricter to where the SPS functionality would have to be completely redesigned to qualify. The only option now, as far as I can tell, is the recently released Enphase IQ8 Sunlight Backup. It's very expensive: I got some quotes and it added about $7k (23%).