Sorry I have been absent so long - DataCenter duties were extreme this last month - I did send them exactly that question RE: can they provide documentation regarding the comm protocol. Will let the group know their response.I've been watching this thread, and suspected this was going to be their response.
I am curious what you happen if you responded with something like: "My battery supplier is interested in making their BMS compatible with the Growatt inverter. They asked for documentation of the communication protocol - could you please provide? Thanks."
I would be interested to see that documentation. Hardware that can speak RS485 is cheap, and relatively simple to engineer. I know that doesn't directly resolve the issue here, but I'd love to build something that connects between the Growatt and BMS (Overkill already has documentation on its TTL UART interface, has Arduino libraries, etc.)