DIY Powerwall is my current hobby. I started by making a 4S6P 18650 pack for my kids 12v quad bike and ever so slightly raised the bar to a 14S21P pack built from Nissan Leaf modules ~ 800ah or 45kwh usable.

I use a Victron Multiplus II 48v 5000VA and three Victron 150/35 MPPTs. The system also has 33 panels AC coupled on the input side of the Multiplus.