Any electricians in the house?

Feasible, I have a gridtie system, and also regularly backfeed using a generator when my local utility goes down - but never both at the same time. I take great care to isolate from the utility mains AND my solar system before I do it (I'm a retired EE with some common sense)

Where do you think the excess power from your solar system is going to go if you're isolated from the main and using your generator at the same time to sync it ?????

Better read this article:
https://www.payperwatt.com/post/can-grid-tied-inverter-operate-in-parallel-with-diesel-generator