Hi everyone,
I was looking at the Virtual Device node in Node-RED and saw the warning in my screenshot.
It says: “Do not use this feature to make an ESS system with third party energy meters.”
This makes me wonder: Why is “Grid meter” even an option in the menu if it’s not recommended for ESS?
Also, wouldn’t using “AC Load” be enough for most cases anyway? Or am I missing a specific reason why someone would need a virtual Grid Meter despite the stability risks?
I’d love to hear your thoughts!
Because it can be used to “play around” with the system, test some things - it just isn’t recommended for production purpose as a lot of meters are just unsuitable to be used as a grid meter and then lead to high frustration if things don’t work as smooth as they should and could.
Grid meters can have different roles, they aren’t purely used for ESS.
A reliable meter is critical for ESS, using a virtual one for this role is a bad idea as it can properly break your ESS.
This functionality is to enable metering for other purposes, for example AC loads like a heatpump etc
Ok, but what is the difference to ‘AC load’ in this case?
And: I think in this case (assigning another role to the virtual ‘Grid meter’), the d-bus value /DeviceType has to be set to something specific, correct? But I think this is too new to be fully documented yet, am I right?
An ACLoad is not undergoing any automatic maths. It’s just metering and tracking “for itself”. Also it has no EnergyReversed Readouts iirc.
A Grid-Meter is significantly involved in determining energyflows in the system, for example the Loads on ACIn are the difference between the grid meter readouts and the inverters ACIN-Measurements.
So, it’s just super critical that Grid-Meters are connected “naturally”. Values beeing readout somehow, roundtripping a mqtt server, beeing picked up by node red to be populated on dbus again… just leads to “uncorrelating values” and therefore errors in depending calculations.
But the biggest reason for not using Node-Red-based Grid-Meters is reliability: If whatever part of the communication stucks, the values may become stale at for example 200 Feedin. The Inverters then could crank up their charge upto maximum chargepower, because they keep seeing that 200W feedin. (or the otherway round and discharge your battery till empty)
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