I was aware that my inverter could connect to the Internet, and probably would be connected to the Internet during setup, but my full intention was to disconnect it following the install. I was pretty happy that the one that the vendor gave me was poll-able from an internal Web server, so I could scrape the metrics myself.
It turns out, none of this was to be. I found out about the Internet connectivity requirement for the warranty _after_ it was on my wall and producing power - and when you've spent five figures on a system with a 25-year warranty, unfortunately I had to suck up my pride and let it phone home to the manufacturer's cloud. It now sits on a separate VLAN for "untrusted" devices.
What's more, I also found out that the manufacturer had intentionally removed the local web server feature, instead making it totally reliant on the cloud service for metrics. It has a laughable rate limit of 300 calls per day, which gives me roughly 5-minute granularity (I could get better granularity if I made my metrics-gathering scripts poll differently overnight, but still), and I really dislike having to reach out to a vendor for data that's produced in my own home.