Planning on 15 kw solar roof with no power wall. I figure I'll take the chance I can use the 3 or future cybertruck as V2G backup.
I seriously doubt that is going to happen without some sort of existing permitted solution (like a powerwall) in place. Also, just to be sure you are aware, in the case of a power outage, that large 15kw array on your roof will sit dormant, and your home will be without power even if the sun is shining.
having lived through 3 days of that last year, I found it EXTREMELY frustrating to know I had solar panels on my roof, sun shining, and yetm food spoiling in my fridge and freezer, and no power.
My bet is any V2G setup from tesla will be in addition to permitted, installed powerwalls, not "instead of". Both because I dont think current charge ports support it, and because if they enable V2G without a verified disconnect source, some lineman working on a line is almost assuredly going to get injured / die. Humans being what they are (forgetful) there is zero chance that if V2G was enabled for everyone, that everyone would remember to throw the main breaker in a power outage situation. Someone would forget, energizing the lines while they would be worked on.
it absolutely 100% would happen, unless there is a technical reason in place that prevents it. Other companies may have some technical way of preventing it other than tesla, but there is no reason for tesla to develop such a solution that excludes their powerwall, for financial reasons.