After an on-site visit and testing by an FCC Enforcement Agent of the ~S9 interference cause to my station by a Solar City solar array located 2 houses away, the FCC issued Solar City a Notice of Violation. It appears that at least one of the primary interference generating components is a load balancing device called an "optimizer" which is attached to back of each solar panel. Testing by the FCC Agent showed that the interference does not stop until the optimizer is detached from the solar panel. Attempts by Solar City to add filters were unsuccessful and only resulted in a few DB of change. The optimizer (as well as the the rest of the system) is manufactured by Solar Edge. I was told by Solar City when I inquired about them installing a different type of system that this is the only kind of system that Solar City installs. Given this it's not hard to envision that many Solar City installations are causing this type of interference. Fortunately the FCC is concerned about this issue and is actively working to resolve it. Got an interference issue? Do your homework and file an FCC complaint. It's what starts the process.