question

dutchsolarfreak avatar image
dutchsolarfreak asked

DESS is not always respecting the ESS max charge and discharge limit settings.

I have asked this in the beta topic but I didn't receive any feedback from Victron.

When I enable DESS sometimes the ESS max charge/discharge power limits are exceeded!

For example:

Today I had enabled DESS and I was charging my EV. DESS told the system to charge by battery from grid.

In my ESS menu I had set the max charge power limit to 2400W but DESS was charging my battery with 3200W! My EV was charging as well from the grid so I wanted to lower the ESS max charge value even further but DESS was still charging with 3200W !?!

@mvader (Victron Energy) Is this normal or a bug?

Shouldn't DESS always respect the ESS max charge/discharge power?

ESSdynamic essess settings
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4 Answers
grua avatar image
grua answered ·

Habe you enabled DVCC? There you can set charge and discharge current limits for the battery which also work with and without DESS

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dutchsolarfreak avatar image dutchsolarfreak commented ·

Thanks grua for your reply

Yes I have enabled DVCC. But DVCC only have a charge limit and not a discharge limit.

It could be that the DVCC charge imit works in both directions (charge/discharge) but for me this sounds more as a kind of "workaround".

I would like to know from Victron if, from a design point of view, the ESS charge/discharge limits should always be respected. Even when DESS is active.


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Dirk-Jan Faber (Victron Energy) avatar image
Dirk-Jan Faber (Victron Energy) answered ·

During the configuration of the system, you are setting the capacity of the system, not the actual limits of the system. These capacities are used by the system to make its calculations.

Also see
https://www.victronenergy.com/live/drafts:dynamic_ess#qwhy_does_the_system_exceed_the_configured_power

So it is normal and expected behaviour. But I agree that we probably could make it less confusing. I'll see what we can do to improve this.

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dutchsolarfreak avatar image dutchsolarfreak commented ·

@Dirk-Jan Faber (Victron Energy)

Thanks for your answer. I understand the calculation part. For calculation the DESS limits are used.

But shouldn't DESS always respect the "actual" ESS charge/discharge current limits?

I am talking about these limits ( screenshot copied from manual in my system these are in Watts):1716797808721.png

1716797958769.png

In other words:

If I enable DESS and I change the ESS charge limit to 1000W, the charge limit should be respected although DESS made a forecast to charge the battery with 3000W?

ESS charge/discharge limits should always be respected in case DESS is enabled.

PS Another issue I mentioned a few times in the beta topic:

As you can see in my second screenshot the option ESS limit AC export power/current is missing. Both in GUIV1 and in GUIV2


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Dirk-Jan Faber (Victron Energy) avatar image Dirk-Jan Faber (Victron Energy) ♦♦ dutchsolarfreak commented ·
We'll see if we can adjust the Dynamic ESS value to be limited by the value set within the Remote Console.
The menu you are looking for resides behind "Peak shaving" / "Pieken afvlakken".
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dutchsolarfreak avatar image dutchsolarfreak Dirk-Jan Faber (Victron Energy) ♦♦ commented ·

@Dirk-Jan Faber (Victron Energy)

"We'll see if we can adjust the Dynamic ESS value to be limited by the value set within the Remote Console."

Thanks and I found the Peak shaving menu.

Still I am bit confused.

I maintain in total three systems and in one system I don't see the menu option limit charge power under the ESS settings anymore. Suddenly it disappeared.

System 1: Option missing firmware 3.40~17

1716809458968.png

System 2: firmware 3.31

1716809591637.png

System 3: firmware 3.40~17

1716809683987.png

Do you know how to fix this?

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dutchsolarfreak avatar image
dutchsolarfreak answered ·

Some example:

DESS was suddenly charging my battery with ~1800W at 2:00 in the night.

1716813683608.png

1716813798989.png

The ESS Max Charge limit was set to 1000W (during the night due to the humming sound of MP)

This is example of a normal DESS behavior during the night (ESS Max charging/discharging limit is set to 1000W)

1716814927732.png


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1716813798989.png (11.1 KiB)
1716814927732.png (15.6 KiB)
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dutchsolarfreak avatar image
dutchsolarfreak answered ·

@Dirk-Jan Faber (Victron Energy)

Another example:

DESS is charging for approx three hours with 3100W. Solar forecast was a bit to optimistic.

ESS Charge Limit was set to 2400W

1716819597392.png

1716819812699.png

By setting the ESS max charge power to 2400W I only want to limit the MP charge power.

If I use the DVCC limit charge current setting it will also will limit my RS solar charger and this is not what I want.


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