I've sent a lot of time researching, and learning about how to convert an EV's ~24 kWh battery pack into a DIY powerwall. There are a lot of videos on YouTube, and even some that suggest it's VERY easy to do - but it isn't, and not exactly easy to tie into a solar array set up with microinverters. Also, you're dealing with high voltages that can cause serious harm, so it isn't exactly a learn-as-you-go DIY project.
Here's a pretty good video that lists what's involved in setting up battery storage that I think was done right. https://www.youtube.com/watch?annotatio ... kXTqNqxK3s
After watching it, and pricing out the components, I'm quite convinced it isn't worth the time or expense, just like a Powerwall isn't worth it either - especially if you live in an area with cheap kWh's. While it's a fantastic concept, I can't see it every paying for itself as things break down, and batteries are, by design, consumables.