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

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dutchsolarfreak asked May 26, '24

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?

ESS dynamic ess ess settings

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Answer 1 · 2024-05-26T12:41:59Z

grua answered · May 26 at 12:41 PM

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 commented · May 26 at 01:28 PM

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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Answer 2 · 2024-05-27T07:46:50Z

Dirk-Jan Faber (Victron Energy) answered · May 27 at 07:46 AM

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 commented · May 27 at 08:22 AM

@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):

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) ♦♦ dutchsolarfreak commented · May 27 at 10:20 AM

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 Dirk-Jan Faber (Victron Energy) ♦♦ commented · May 27 at 11:37 AM

@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

System 2: firmware 3.31

System 3: firmware 3.40~17

Do you know how to fix this?

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Dirk-Jan Faber (Victron Energy) ♦♦ dutchsolarfreak commented · May 27 at 01:13 PM

One system probably has DVCC on and the other one not. For DVCC systems, the charge current limit is in the DVCC menu, and set in amps.

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dutchsolarfreak Dirk-Jan Faber (Victron Energy) ♦♦ commented · May 27 at 01:38 PM

@Dirk-Jan Faber (Victron Energy)

System 1 and system 2 DVCC enabled.

System 1 limit charge power not visible and in System 2 limit charge power is visible

System 3 DVCC disabled. limit charge power is visible

In the past Limit charge power was also visible in System 1 where DVCC is/was enabled and was working as expected. I set the limit using a nodered flow to reduce the noise of my MP during the night.

Since a few weeks the option is not visible anymore in system 1

I would appreciate to have the option back (when DVCC is enabled)

Using the DVCC charge current limit will also limit my RS charger and there is no need to limit these.

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Answer 3 · 2024-05-27T12:45:24Z

dutchsolarfreak answered · May 27 at 12:45 PM

Some example:

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

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)

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Answer 4 · 2024-05-27T14:29:47Z

dutchsolarfreak answered · May 27 at 02:29 PM

@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

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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