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puitl avatar image
puitl asked

VRM-Dashboard bar-diagramm: Grit feed-in compensation of single phases really only with energymeter solvable?

Hello!

To get the correct kWh-values for grid- & battery-consumption in the VRM-Dashboard bar-diagramms, using an 3-Phase ESS, it is necessary to install a energymeter like the EM24.

Is this really the only solution?

I mean: The amps and watts for grid feed-in of single phases are measured correct and shown in the extended-diagramms, so Victron "detect" them correctly.
Also the kWh for total consumption are correct compared to the energymeter from the grid-operator.


In case of this it could only be an error in the VRM-programming, can it?

Or is it not that easy?

VRM
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2 Answers
mvader (Victron Energy) avatar image
mvader (Victron Energy) answered ·

Hi @Puitl ,


With quite a lot of work now, and in the future to keep it working properly, we could make it somewhat ok. But never really good, since we will be measuring and counting per phase, in individual devices (each Inverter/charger), and then elsewhere bringing it together.

Instead of how a utility meter and EM24 does it: measure power on all phases in one device. Add them together, without latency, to get total power aka nett power, and then integrate that over time to get to Energy.


So, with that being a lot of work, and not a real good solution, I’ve decided to for now not do that.

The ESS team is working on other projects, such as speeding up ESS, which I decided has a higher priority.

I’m sorry about the metering differences.

Matthijs


Ps. i’m assuming this is about differences between VRM Portal dashboard & utility meter. Where the VRM can show excessive power in and out from the grid, which issue increased per Venus OS v2.80 because that better handles the “total on all phases” regulation mode.

So, in other words, what happened in Venus OS v2.80 is that we improved the ESS algorithm, but at the same time increased kWh reporting errors that appear on systems not using an EM24 for the energy metering.

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puitl avatar image
puitl answered ·

@mvader (Victron Energy) Thank you for your fast and perfect answer, sounds understandable!

Another nearly similar question:
I have an 3-Phase ESS with Multiplus 2, MPPT, Cerbo-GX and a DIY-Lifepo4 48V battery (no battery monitor and a "stupid" BMS with no communication to victron).

With the Lifepo4 standard-setting in the VEconfig (56,8/54V) the SOC increases linear related to the kWh which are getting in the battery - everything perfect.
BUT
when i set the absorbtion- and float-voltage BOTH to 55,2V, the SOC increases immediately from (for example) 35 to 95% when there is suddenly high generator-power in the system.


Do you know why?
Is it because of the same voltage-settings for absorption and float or is the SOC-measurement faulty in general when going away from the standard-setting?


Thank you!

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puitl avatar image puitl commented ·
Problem solved:

55,2V is a little bit too low. The battery comes very close to this voltage when it will be charged with lot of watts and so the SOC shoots up.

At my config the VRM measures about 0,3V more than multimeter is measuring direct on the battery so that exacerbates the problem at low voltage like 55,2V.

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kevgermany avatar image kevgermany ♦♦ puitl commented ·
Could be your BMS...
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puitl avatar image puitl kevgermany ♦♦ commented ·
my BMS has no communication to Victron :)
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kevgermany avatar image kevgermany ♦♦ puitl commented ·
You said you were measuring direct on the battery. Usually when multi shows higher voltage than battery, there's a poor connection or other resistance. So where is the difference? Might be across the BMS.
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puitl avatar image puitl kevgermany ♦♦ commented ·

Sorry my mistake: VRM shows up to 0,4V less compared to BMS and multimeter directly on the battery - more voltage drop at higher amps, this is because of the cable-resistance from the battery to the multiplus.

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