I assume you would like to use Enphase micro inverters with a DIY battery.
That was my first question when I came here. I ended up using a hybrid inverter and no micro inverters.
In the future, I plan to add some panels with micro inverters and feed them through generator input of the hybrid inverter.
Some people use micro inverters and feed them all through the generator input on a hybrid inverter.
You probably don't like those ideas. Hopefully someone will have some better ideas. I will be watching this thread.
Currently have a 13.3 KW enphase iq7 system. Idea is to feed the output from the EQ combined into the enphase smart switch. Then setup the batteries with iq8+ To the smart switch. I believe the controls are all built into the smart switch and the BMS functionality is from the iq8+