If there's an electrical link between your system and the public grid, you're playing by the grid's rules. If you don't want to play by the grid's rules, you can't connect to the grid in any way.

p.s. Even if buy-all-sell-all doesn't make sense, requiring your electrical setup to meet grid standards does make sense. It's be surprisingly easy to cause a blackout, or to kill yourself, by messing it up.