Hi,
I have just ordered this plug + USB adapter since I will have a Solis inverter running in my garage very soon.
I have a Solis WiFi stick also (Generation 3) that I will use to test things but then my plan is to go with a Raspberry Pi Zero W (first model that I had in box just collecting dust…) to read the data from the inverter to HA, as little cloud as possible is my goal, using this project GitHub - incub77/solis2mqtt: Modbus RTU / RS485 to MQTT bridge for Solis Mini solar inverter.
Since I don’t speak german I used Google translate to help with that image @sticilface posted (See image here), I have 0 experience with modbus so far but as I understood the text on the image I just choose either D- och D+ and connect the Ground pin to either? (Not both obviously 
)
Is that a correct assumption or did my translation end up horribly wrong?
I also plan to run the Pi Zero W from the connector on the inverter since I read the WiFi stick can use up to ~5W in the technical details, that should be plenty for the Pi Zero W as I understand it, or can someone tell me that is a bad plan before I even try it?