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nonkeldw avatar image
nonkeldw asked

ESS very slow with EM540

Hello

This is my first post on the forum. I want to use Victron, for my ESS. I invest in Multiplus II - GX with an EM 540 powermeter (RS485) suggested by my distributor.

After configuration a got very bad result! When we start the ESS assistant the power to the grid is regulated but very slow! With a very big delay and big span -100W - +100W range, when 0w is configured.

Why this delay?

I read already a lot on the forum, most of the users gives the powermeter as problem. But I invest in a new powermeter with an update rate of 100mS, instead of 500ms or 1000ms. (https://www.gavazzionline.com/em127.htm#:~:text=Both%20EM530%20and%20EM540%20feature,storage%20or%20EV%20charging%20applications)

I was wondered how the powermeter communicates with the inverter, Victron use the baudrate of 9600!?! Why?

Is Victron busy with creating any solution of this problem?

Multiplus-II
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daniel-feist avatar image daniel-feist commented ·

3-phase supply? Which model of the meter do you have (X, PFA, PFB or PFC)? Is your utility meter vector-sum?

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nonkeldw avatar image nonkeldw daniel-feist commented ·

Yes, 3F system. I configured B mode. Is your utility meter vector-sum? => Yes

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5 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

The system always needs time to react to changes.

Just because the EM540 is sending the information every 100ms doesn't mean the system can react that fast.

With the coming Venus OS 3.00 it will become a bit faster but it will never be instantly and the power will always vary around the gird setpoint.

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larsea-dk avatar image larsea-dk commented ·
@Matthias Lange - DE could it be possible for us having trouble with this slow reacting multiplus/easysolar (hardcoded 400w/s change) to have a button/setting where we can slow down the power change from mppts? And additional to work from soc above a certain percentage SOC? I think this will help regarding these over voltage issues people have. Most buy battery sizes that fits their actual need and not a size “dictated” by a system that do not take this into account(slow reacting feedin).
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nonkeldw avatar image
nonkeldw answered ·

So these big fluctuations are normal? At my work we got Fronius, same setup, powermeter ESS system, this fluctuations are les, + - 10W, that's acceptable for me.

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hominidae avatar image
hominidae answered ·

Fluctuations can be high, when you either have a very large PV array (and cloudy weather - I see up to 12kW peaks with my 20kWp array easily) or larger loads (like when charging an EV with PV ony). As said, the ESS reaction is not instantaneous.

What it all comes down to in ESS is, whether these fluctuations will add up on your bill.

If feed-in is allowed, what helps is to set the grid-setpoint to a small negative value, like .-15 or -25W. Also, as said with v3.00(currently beta) the ESS loop got very much faster with an EM540 as grid meter). Both options result in a lower consumption from the grid. My setup, with a 3ph MP2-5000 setup only consumes 0.2-0.6kWh per day, which isn't too bad.

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kds avatar image kds commented ·

Interesting. I can't tell how similar are our installations: I am exactly in the same range 0.2-0.6kWh per day (grid set-point set at -10W) with a MP2 48/5000, 13.5kWp PV, venus OS v3.00, but a Eastron sdm630v2 smartmeter instead, pulled every 500ms (my personal tests gave me a 2.2Hz max frequency for this device vs 10Hz for the EM540, right?).

Initially, I was considering to move from my Eastron sdm630v2 to EM540... So I am now skeptical there would be any benefit at all to make that move.

Please let me know your thoughts.

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pedaaa avatar image pedaaa kds commented ·

i use EM540 with -80W Gridsetpoint and have ~0,0-0,1kWh per day consumption. Sometimes 0,2kWh.

But its really hard to get to "real" 0,000kWh grid consumption on an ESS.

Its only possible if i use -250W gridsetpoint or so. What i somtimes do in summertime, as PV and battery are big enough and i get good payment for grid feed-in

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daniel-feist avatar image
daniel-feist answered ·

Assuming you have the non-MID EM540DINAV23XS1X version of the EM540, you need "C measurement" mode if your supply is vector-sum and you want Victron to aim at keeping import/export 0 watts and to correctly phase compensate.


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hominidae avatar image hominidae commented ·

...according to the data sheet (https://www.gavazzionline.com/pdf/EM540_DS_ENG.pdf) the measurements mode only impacts the way of the aggregation of Energies (sum, kWh), not actual Power measurements per phase (the default mode is A)

AFAIK, ESS does not make use of Energies, only Power (per phase or phases combined, which is a setting in the GX only and not related to the measurement mode configuration).

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daniel-feist avatar image daniel-feist hominidae commented ·

I don't know all the details, but if "B measurement" worked, then the EM540DINAV23XS1PFB model of this meter would be listed in the Victron meter guide. Instead, it is not specifically not listed.

Do you have a reference for where it says Victron only uses per-phase energies and does not rely on the meter to aggregate power over phases? Even if you are right, there would be no harm in switching to "B" vs. "C".

https://www.victronenergy.com/upload/documents/Datasheet-Energy-Meters-Selection-Guide-EN.pdf


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hominidae avatar image hominidae daniel-feist commented ·

no, I don't have a specific info / reference regarding that.

Besides that the recommended Version for DE is either the non-MID variant, for which the default measurement defaults to "Mode A", or the PFC (MID), as stated in the official datasheet.

In other forums, people who are using the non-MID variant (model EM540DINAV23XS1X) seem to do fine when using ESS without further adjustment of the mode settings in the meter.



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daniel-feist avatar image daniel-feist hominidae commented ·

Interesting. My assumption was EM540DINAV23XS1X was supported because it supports "Mode C", but if Victron isn't using total power, then A/B/C should all be fine, and this would mean that the meter mode is unrelated to the OP's question.

That said, I plan to configure my EM540DINAV23XS1X to use "Mode C" just to be sure, and so that any kWh values reported by Victron match what my utility is actually metering me for. I would say that it's a good idea, for anyone that is sure they have a vector-sum grid meter, to do the same, to avoid historical grid figures being incorrect (i.e. not matching billing). Looks like Victron also recommends this.

See:

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/multiphase-regulation---further-information.html

https://www.victronenergy.com/media/pg/Energy_Storage_System/en/faq.html#UUID-169dbd85-4b6f-814b-33c2-9fa77a6973d2_section-idm4566394098950432915191768657

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hominidae avatar image hominidae daniel-feist commented ·
my electrician will hopefully swap my EM24 for the new EM540, that is already sitting on my desk, soon..

But yes, I think the modes A, B or C are not related to the OP's problem.

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ulfilas avatar image
ulfilas answered ·

Hello, is anyone using the B version?
I want to set up an EM540DINAV23XS1PFB with an RS485 to Ethernet gateway but Cerbo does not list my meter. But i can reach it with node-red and UCS software.
Does Victron only supports specific Versions of the EM540?

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daniel-feist avatar image daniel-feist commented ·

Is your grid meter vector-sum? If it is, then you really want C or X version.

The B version will work for phase compensation (as this uses power apparently), but anything that uses or reports kWh will be incorrect.

If your grid meter is not vector-sum and import and export are billed separately then B is the correct version.


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ulfilas avatar image ulfilas daniel-feist commented ·

I am not using the EM540-B as grid meter i want to log AC-Laoads without phase compensation.

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