Battery storage remains constrained by cell availability. There is no spare capacity and it can only be scaled up slowly due to supply chain issues. The battery storage that Tesla sold to Australia is a step in the right direction but capacity is only a tiny fraction of what we would need in the USA to enable a large scale transition to renewable energy.

https://www.cnbc.com/2021/12/08/australia-switches-on-victor...

The California grid operator has a really cool website that shows realtime-ish graphs of supply and demand[1] and even daily battery reports[2]. One big takeaway is that the total battery capacity is kinda wimpy when you compare it to how much fossil fuel the state burns over the day.

The way net metering worked in the past is that people with solar could offload their access generation to power companies and make storage or resale the utility's responsibility. Then 2.0 was a sorta-time of use implementation, and now we're up to Net Metering 3.0 and I haven't bothered to look into how that works. However people I know who have looked into Tesla powerwalls haven't found them to be economical for individual homeowners.

[1]: https://www.caiso.com/TodaysOutlook/Pages/supply.html

[2]: http://www.caiso.com/Documents/DailyEnergyStorageReportJun22...