Buddy of mine has 2 Tesla power walls and like 25 or 30 solar panels. He is still tied to the grid but that’s because he got the power walls for cheap thru GMP but they are allowed to pull from his power walls during peak times. That said if they were his alone I believe he could be 100% off grid with this setup. But obviously it depends on your exact setup. How much sun does your home get for your panels and how much power do you need on a daily basis.

You will still want to be tied to the grid as well, even if you fully own your power walls. You can sell the surplus power to GMP, but also during winter if your panels cannot produce enough power to charge your power walls,you can pull from the grid and still have power. And it will just consume some of the credit you have with the utility company. The only way to offset this need is to have extra panels, and extra power walls. But that means $$$.