Sounds like a very useful and fun project. You might want to look into a vendor membership upgrade and start your own thread here on TMC.Model 3/Y batteries can now be used for solar storage with HV inverters, thanks to this awesome open source project:
GitHub - dalathegreat/Battery-Emulator: This software enables EV battery packs to be used for stationary storage in combination with solar inverters.
This software enables EV battery packs to be used for stationary storage in combination with solar inverters. - dalathegreat/Battery-Emulatorgithub.com
I build and sell controller kits that are pre-wired for Tesla batteries.