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spithost avatar image
spithost asked

ESS System not feeding in grid :-(

I got a 5k MultiPlus II running with a set of 10kWh BYD LiFePo4 batteries (with their own BYD BMS) en two DC-connected MPPT's with a total PV-capacity of around 2400Wp and a Cerbo "running things"..
The Cerbo is updated to the latest firmware (automagically through the internet). The MultiPlus II is on firmware 2623470 and runs the ESS-assistant more or less with the default values of the German gridcode with internal NS protection.
The only thing I didn't let the assistant change, is the type of battery (because of the BYD-specific settings for Absorption and Float).
This time of year I have quite a surplus of PV-energy so I started experimenting with ESS (Optimized with BatteryLife).
For some reason the system is NOT feeding the surplus of PV back to the grid :-(
Only if I set the grid setpoint to a negative value, the system starts to feed back the PV to the grid at the height I set the negative grid setpoint to....
Otherwise, the BMS (I think) switches off the MPPT's so they don't deliver any PV anymore :-(
For some reason it does that when the BMS says (at VRM and in Remote Console) that the batteries are at 99% instead of 100%. I have no idea why it does that but this doesn't bother me too much ;-).
I set the minimum SOC (unless grid fails) at 95% otherwise apparently the system thinks it should feed the loads from the grid, even when there's still enough PV to do that and even enough to charge the batteries.
So not the actual surplus of PV energy is fed into the grid, but the value set with the negative grid setpoint...
So when there's a cloud before the sun and the batteries are still above the minimum SOC (unless grid fails) then the system feeds the grid from the batteries if the PV drops below the value set in the negative grid setpoint....
I probably have some setting "wrong" to get this result, but I can't seem to think of what could be wrong....
If someone has suggestions..... they are more then welcome.

ESSsolargrid
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netrange avatar image netrange commented ·

Setting in the ESS menu ...

Feeding back into the grid from DC PV allowed ? YES or NO ?

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seb71 avatar image seb71 commented ·
Post screenshots with all settings from ESS (including sub-menus).
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marekp avatar image marekp commented ·
@Spithost

Set "ESS>Mode>Keep the battery charged" and see if PV-DC will feed the grid.

PV-DC will not feed the grid unless battery is charged.

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spithost avatar image spithost commented ·
Actually ESS now is working "partly". But as the cause is probably different, I will open a new "case".
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9 Answers
marekp avatar image
marekp answered ·

@Spithost

screen-shot-2022-06-26-at-34653-pm.pngIs "DC-coupled PV - feed in excess" set to ON?


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lifeingalicia avatar image
lifeingalicia answered ·

Hi

1656251036477.png

did you activate this ?

1656251256359.png

From my experience Grid set point and SOC play together.

My system multi 3 only loads excess into batteries except if I go below SOC.

I have also limited charge and inverter power but that is because I can....

Hope it helps




1656251036477.png (23.2 KiB)
1656251256359.png (26.3 KiB)
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lifeingalicia avatar image
lifeingalicia answered ·

You probably need DC feed in - it has higer losses but sun is free.....

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lifeingalicia avatar image
lifeingalicia answered ·

Dont forget to check Battery mode - this determins priorities

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spithost avatar image spithost commented ·
what do you mean with Battery mode?
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spithost avatar image
spithost answered ·
Thanks for the suggestions, but I allready had this set ;-)

I set it to 2000W (maximum feed-in)
I don't have AC-coupled PV, so I left this off.


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marekp avatar image marekp commented ·
@Spithost

Do you have DVCC enabled and configured?

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spithost avatar image spithost marekp commented ·
That is sort of "set" automagically. I didn't change that.
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marekp avatar image marekp spithost commented ·
@Spithost

Can you show here your DVCC settings?

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spithost avatar image spithost marekp commented ·

here it is ;-)1656332434535.png

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1656332434535.png (84.6 KiB)
netrange avatar image
netrange answered ·

Feed back to the Grid ... when Gridsetpoint = 0 and DC Feed Back ON ... only if Battery is full !!!

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lifeingalicia avatar image
lifeingalicia answered ·

did you solve it ?

check this

1656319031192.png

And within the ess assistant is battery mode

https://www.victronenergy.com/upload/documents/Energy_Storage_System/ESS_design_and_installation_manual-en.pdf

4.3.1 and 6.2


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spithost avatar image spithost commented ·

The settings from paragraph 4.3.1 and 6.2 are set to Optimized (with BatteryLife).
For some reason, the system "swings" between the SOC-point of 95% (discharging from around 99% from the batteries with -1500W set in the (negative) grid setpoint) and then charging the batteries again with PV to a point and using the grid to power the loads :-(.
I have no idea why it uses the grid to power the loads, because there's more then enough PV to cover the loads AND charge the batteries....
If I'd know a way to let the system NOT use the grid for the loads, during the charging of the batteries with PV, it would be working the way I'd like and would expect of ESS...

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marekp avatar image marekp spithost commented ·

@Spithost

Setting min SOC to 95% and the "Optimized with Battery Life" is confusing your system.

"Optimized with Battery Life" will keep battery charged higher and higher if battery is not charged above previous SOC and lower and lower if it does go over previous SOC, but would not go above 80% SOC. With Min SOC at 95% the "Optimized with Battery Life" has nothing to do.

You are practically keeping your battery charged all the time.

If you want to do that, it is better to select the option "Keep the battery charged" instead "Optimized with Battery Life".

Once the battery is charged your PV will be fed to grid if nothing else is preventing it.

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spithost avatar image spithost marekp commented ·
If I would choose to keep the batteries charged, it would charge the batteries at night using the grid, when there's no PV right?! That sort of defeats the purpose, because then the grid still would be used during the night (which I want to prevent), to power the loads AND keep the batteries at 100%. So my guess was to set Optimized with BatteryLife and a SOC of 95% as a "target" for the PV during the day (the SOC will drop to around 80%, during the night and powering the loads when NOT having grid available).

And because it states in the ESS-manual, at the explanation of BatteryLife, that it eventually will try to get the SOC up to 100%, I thought 95% being a nice point to start out with...?

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marekp avatar image marekp spithost commented ·

@Spithost

Sorry but I do not understand.

Is this 95%SOC a Minimum or Maximum value for SOC. If it is the maximum than were did you set it to that value.

It is certain that I do not know everything but in my Remote Console in ESS I can find only this setting regarding SOC:

screen-shot-2022-06-27-at-25056-pm.png

"Minimum SOC {unless grid fails}.

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spithost avatar image spithost marekp commented ·

Your answer made me think..... I set the minimum SOC (unless grid fails) to a lower value (60%) and the grid setpoint back to 10W. The loads are now "done" by PV when available and the batteries at night.
I was hopefull that when the batteries were full, the excess PV would now be fed into the grid, but.... no such luck.
Apparently now the MPPT's are under control of the BMS again (I think), because the MPPT's are switched off when the batteries are "full".
The loads are done by the batteries until the SOC drops a bit and the BMS switches PV on again. Then the batteries are charged again with PV until they are full etc etc....
So.... still at the same "spot" :-(

Maybe it's because the batteries never "reach" 100%, according the BMS, for some reason. And ESS keeps thinking more power is needed for battery-charging so it will not feed into the grid.... It charges to 99%..... then keeps charging some more but never goes to a full 100%.
Only when I DON'T use ESS and have grid connected, eventually the batteries go to 100%. There isn't a ESS-setting that enables you to feed the grid with the excess PV when the batteries reach 99% I guess?!
That's the reason I fiddled a bit with that minimum SOC (unless grid fails) setting I guess..... but to no avail....

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marekp avatar image marekp spithost commented ·

@Spithost

I suggested you twice already to set the mode to "Keep the batteries charged" as a test if your system would actually charge your battery to full. If it will then the PV-DC should start feeding the grid when the settings allow for it.

If it does not, look for the battery settings that prevent it. The BMS inside your BYD batteries is telling the system the SOC (I think). I do not know BYD BMS so maybe some else would help you with it.

Maybe installing SmartShunt would fix the problem.

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spithost avatar image spithost marekp commented ·
When I do that, the grid takes care of the loads, and the BMS still prevents the MPPT's from doing their things....

Apparantly there is a difference between what the BMS thinks the SOC is and ESS. I suspect ESS only redirecting PV to grid when the batteries are at 100% (hard coded or so...) and for some reason the BMS stops before reaching that 100% and still reports 99%.


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marekp avatar image marekp spithost commented ·
@Spithost

Can this BYD BMS work as "2 signal BMS"?

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spithost avatar image spithost marekp commented ·
I THINK the communication goes by VE.Can...
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marekp avatar image marekp spithost commented ·
@Spithost

Ask BYD service why your battery never reports 100% SOC.

As you stated, PV-DC will feed the grid one the battery is full.

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spithost avatar image spithost marekp commented ·
it GETS to 100%, but only when charged by grid....
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marekp avatar image marekp spithost commented ·

@Spithost

Only when I DON'T use ESS and have grid connected, eventually the batteries go to 100%.

ESS is active as long as assistant is loaded.

Two questions:

1. Do you take ESS assistant out when you say "I DON'T use ESS"?

2. Do you run your system with ESS assistant loaded only when is disconnected from the grid?

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wkirby avatar image
wkirby answered ·

Do you have the "Use Aux1 as disable FeedIn signal" box set?
You need to un set this box if Aux1 is being used for something else. If Aux1 is closed then FeedIn will be disabled, unless you clear the box.

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marekp avatar image marekp commented ·

@WKirby

But he sais:

Only if I set the grid setpoint to a negative value, the system starts to feed back the PV to the grid at the height I set the negative grid setpoint to....

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wkirby avatar image wkirby ♦♦ marekp commented ·
Hej Marek.

Yes, I did notice that, but just want to make reduce all of the possibilities.

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marekp avatar image marekp wkirby ♦♦ commented ·
@WKirby

I just wanted to make sure that I understand this as I know that do not know everything. :)

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spithost avatar image spithost commented ·
I don't use Aux1 for anything, so I thought this wouldn't be of any consequence? I guess Aux1 will be open, when it's not used?
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wkirby avatar image wkirby ♦♦ spithost commented ·
OK, then this is not relevant for you. Just was to close all the possibilities.
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lifeingalicia avatar image
lifeingalicia answered ·

Just thought - do you use external CT? If so try turning it....

If not - sure phase is on phase and neutral is on neutral.....??


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spithost avatar image spithost commented ·
What's CT? I have the wires connected as they should be. I once had them different and the whole system went nuts :-D


So, since then, I'm VERY carefully that phase is on phase and neutral is on neutral ;-)
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