Matt Ferrell has the text to his YouTube video about the Tesla Powerwall, Sonnen, etc. and a link to the video. The Tesla Powerwall and others cost about $10,000 installed. The systems may allow you to run your home from the battery when there is a power outage on the grid. Solar PV panels will charge up the batteries when the sun is shining. The text gives some of the specifications for the various brands.
https://undecidedmf.com/episodes/2020/9/2/exploring-tesla-powerwall-and-home-batteries-worth-it