Mike - try this project and let me know if it works for you if you’ve given up on the SNMP method (it should In theory be the same rs232/USB protocol for the 10kw version as my smaller 3) - Programmatically read data from your Solar Inverter (Voltronic, Axpert, Mppsolar PIP, Voltacon, Effekta etc) and interface with Home Assistant via MQTT - Works with RS232 & USB!
It’s designed to be run in Docker, so it can be deployed on a cheap SBC (such as an orange pi) next to the inverter, which then communicates with HA via MQTT…
You can also use HA to send commands TO the inverter this way (such as changing battery cutoff and float voltages, charge modes etc).
If you live in a hot climate like me (Australia) I’d suggest also adding in a DHT22 temperature sensor to your battery box (assuming you have one) and wiring it to the PI also - this way if the batteries are above normal temperature, you can programmatically change the charge voltage/amps on the inverter (via a HA automation) so that you don’t damage them when charging them in at hotter temperatures