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jeanmarie avatar image
jeanmarie asked

Problem in understanding the AC-IN intake from an ESS installation

Hi community, I have some understanding problems about what my ESS is doing, sometimes, and sometimes only, this is my biggest concern.

I have a basic ESS with MP2 10k, Primo 3kW, RS450/100, Cerbo and 84kWh of DIY batteries

I noticed that, sometimes, the ESS, instead of, as usual, managing to balance between available sources to feed my AC Load, start to pull the maximum it can from my AC-IN (limited to 14A by settings)

Like in the example below, at 11h40, it start consuming a maximum from AC-IN despite batteries were almost full. and it continues when batteries were full by even stopping the RS450 (green line) before to awake from it's mistake and go back to a "normal" status.

It is repeated at 12h54 where batteries were full and even worse as here it stop the MPPT to take from the grid!

capture-du-2023-06-26-07-53-03.png


The basic work around is to switch off the grid, but this make the ESS worthless.

And for those arguing about compatibility, yes my BMS are Seplos models, not "approved" but in that typical case, DVCC is enabled, CVL, CCL and DCL from BMS are at the maximum and CVL is voluntarily downgraded to 55.5V from DVCC menu to avoid working at high voltage in the battery during the summer months.

I would be grateful if someone could explain me why the CErbo is behaving that way and mostly if there is any chance to correct this behavior by changing any of the parameterization (or programming?)

ESSac-in
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5 Answers
Alexandra avatar image
Alexandra answered ·

@jeanmarie

How heavy is your node red load?

I have seen when the cerbo gets hot and then with extra loads on processing, strange things can happen. So you could improve cooling or reduce the node red dashboard and processes. Reduce logging intervals.

The simplest fix which I know you won't want to hear, is get a BMV.

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jeanmarie avatar image
jeanmarie answered ·

Hi @Alexandra and thank you for your feedback

Don't know where to look at to know my node red load but there are only 2 scripts

- one, that run once every hour to calculate the forecast production

- one that run cyclically to estimate if CVL should be altered between 55.5 or 56.3 (to ensure SOC synchronization) based on 3 values (CVL, SOC and Ubat)

I just checked the Cerbo and it is warm but not hot.

Regarding the fix, I have one simpler that cost nothing : switch off AC-IN.

But this is not really satisfying as it prevents me from injecting the excess AC (I'm not paid for, it's just better for the planet)

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Alexandra avatar image Alexandra ♦ commented ·

Interesting. Is it a keep batteries charged system?

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jeanmarie avatar image jeanmarie Alexandra ♦ commented ·
No it is a basic ESS system where solar panels are ensuring almost all the consumption during 8 to 9 months
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Alexandra avatar image Alexandra ♦ jeanmarie commented ·

Are you cycling your batteries?

Under ESS you can set the system to keep the batteries charged. Sometime that causes the charge from grid

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jeanmarie avatar image jeanmarie Alexandra ♦ commented ·
Yes, my mistake, sorry for not being detailed enough


it is set as "optimized without batterylife" permanently.

Everything is working well most of the time, except during those moments as shown above.



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jeanmarie avatar image jeanmarie Alexandra ♦ commented ·
Hi Alexandra and thank for you for your interest in my case

No I'm not in the described case as

- batterylife is not enabled

- SOC , in that season, never goes lower than 80%

- Sustain voltage is set at 51,20V (voltage is changing between 55,5V and 53,00V

- Dynamic cutoff is set between 40 and 42,50V

As I was reviewing my MP configuration, I noticed 2 points that I'm not sure about consequences in the described case

- my float voltage is set to 55.50V but my absorption voltage is set to 56.50V ( as said this is not influencing the charging process that goes well to fixed CVL of 55,5 and once a week jump to 56,3)

- when opening my configuration I get a warning that my assistant (unique one is the ESS) is not at the latest version


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jeanmarie avatar image
jeanmarie answered ·

One more example of the strange (to stay polite) behavior of my ESS

It is jumping between taking from grid / stopping and even switching off the MPPT instead of switching off the AC-IN intake

capture-du-2023-06-27-14-42-15.png

But this is useful as it force me to find a workaround and I found a much cheaper option than the suggested BMV, @Alexandra : limiting input current to the minimum allowed : 1A. Like this the ESS can toggle between sources like crazy but at least it will not take several kWh from grid while there is plenty of sun power available



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Alexandra avatar image
Alexandra answered ·
@jeanmarie

With DVCC on and the battery control the settings on the components would be ignored unless the bms lost connection. But then that would throw up errors anyway.

Yeah the waening would be bescaus your ve config updated, there are new versions of the assistant. There are some improvements in firmware being rolled out for wind and solar priorities.

Possibly updating the all the system components might help? But then could also create other problems.

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jeanmarie avatar image
jeanmarie answered ·

Yes @Alexandra , this is the main issue when updating a system to the latest version, as old programmers often says, why attempting to fix a fully functioning system.

Should be taught to all those aficionados of google, windows and other modern stuff where their smartphone spend half of the time and takes a quarter of the bandwith to update.

Back to the issue, the latest ESS assistant version is 0184 and I have the 017E, unfortunately the changelog assistant doesn't mention this 0184 version

Could any Victron staff member like you @mvader (Victron Energy) or anyone else update the changelog for assistant with latest changes?

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Related Resources

What is ESS training video

ESS Quick Installation Guide

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