Hey yeah, I looked at the Powerwall 2 manual as well as this:
My reading on the Solar Shutdown Device is that it's part of an automated system that triggers on "Loss of AC power". So it's not a manual shut-off. OHHHH, I just had a thought. If it was tied to the breaker for my system, then it ought to trigger a shutdown when I flip that breaker.
So on the side of my Backup Gateway, I have this sticker:
View attachment 695729
The "switches" in this box are the main breaker, and a breaker for the solar system.
I guess tonight I will try flipping that and leaving it off for a few minutes and see if
that actually "stops" the inverter. I'm pretty sure I tried this before, and my Powerwall kept it up and running. Perhaps I should use the web-based STOP SYSTEM to stop that first.