I now have ten days (minus about four hours) of solar operation. The Tesla app has a page called Impact. It shows that over those ten days 14% of my power came from the grid. That may excite me, but since I’m not using all that much power it shouldn’t be of much interest to anyone else. If I used more it would ALL be added to that number.
On the other hand, the breakdown of the other 86% goes directly to the impact of having the two Powerwalls. The 86% breaks down into 39% coming directly from solar, 47% coming from the Powerwalls. Since I can not currently sell back to the grid, that 47% would not have been there, it would have just been unusable excess, if it couldn’t be stored. Which ties back to Goofyhoofy’s statement about having an oversized system that doesn’t feed the grid. Batteries make a major difference!
(About the Powerwalls… Each is rated at storing 13.5kWh, so 27kWh total. I’ve have had the system set to not draw down below 35%, so I’ve been using up to 17.5 kWh of that capacity.)