To have a Victron BESS be able to have net 0, I would install an ET-112 energy meter. However, I already have something connected to my P1 port that reports house power draw to Home Assistant.
Would it be possible to send this data to a GX device (using modbus-tcp, or mqtt), so I don’t need a separate energy meter? Does anyone have experience with such a setup, or reasons to (not) recommend this approach?
Use nodered and new virtual devices. Create a virtual EM and send the relevant data to it.
You mean… nodered with virtual devices as introduced here Virtual devices from Node-RED - #12 by keesoomen and so would run Venus OS Large on Multiplux II GX, set up a virtual grid meter and ESS would use that to determine whether to charge or discharge/power assist. Right?
How would the data get from HA to the virtual gridmeter?
How does the existing meter send data to home assistant? Does it have MQTT? If so, you would subscribe to the MQTT topic from within node red.
Modbus/MQTT