question

bernhards avatar image
bernhards asked

Disable MultiPlus 2 charger in summer days

Scenario:

- Multiplus2 in ESS mode

- MPPT

- Cerbo GX


During sunny days, the battery is heavily loaded by the Multiplus2 which is not what I want. The solar modules of the MPPT are delivering enough energy during the day to load the battery so that the other PV inverter can feed in to the public grid and earn $.

In the Cerbo GX setting in the device Multiplus2 there is a setting 'switch' to set the device in inverting only but this does not really work - it stops charging but blocks inverting, too

Is this a bug of the CerboGX or only works without ESS? Is there another solution - which can be controlled via ModbusTCP later on?


I thought this is a standard scenario to get the most out of the devices.


Best regards

Bernhard




Multiplus-IIcerbo gxbattery chargingMPPT SmartSolarModbus TCP
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11 Answers
nickdb avatar image
nickdb answered ·

In invert mode it won't charge and it does supply loads with the MPPT and Battery.

Grid is dropped so PV inverters can't backfeed.

Charger only mode, will passthrough grid power and will not invert, mppts will only be used for battery but PV inverters should still operate aiui.

Not sure if you got your modes confused, but that is definitely how it works.

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floki avatar image
floki answered · 
Hello
Simply set the Cerbo GX under ESS->Limit charging power = switch on
and
Maximum charging power to 0 W
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nickdb avatar image nickdb ♦♦ commented ·
Nope. That will also stop every MPPT from doing anything, including supplying loads.
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floki avatar image floki nickdb ♦♦ commented · 
Das stimmt nicht, 

ich habe die Ladegrenze des Multiplus 2 auf 0 W eingestellt. 

Der AC-Wechselrichter ist voll kostendeckend, der Mppt auf der DC-Seite speist alleine die Batterie. 
Wenn die Batterie voll ist, wird der PV-Überschuss vom AC- und DC-Wechselrichter ins Netz eingespeist!
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Duivert NL avatar image
Duivert NL answered ·

normally you dont have to worry about this, ESS will do that automatically

PV power > charge battery > surpluss house load > then grid feed in

and if batery full same: surpluss house load > then grid feed in


or am i misunderstanding your question?

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bernhards avatar image
bernhards answered ·

Well, I want to charge the battery with the MPPTs only and let the Multiplus2 just run. The pv inverters are not connected on the Multiplus2.

Limit charging power would limit the MPPTs, too I guess?

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nickdb avatar image nickdb ♦♦ commented ·
Yes it stops all DC generation.
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Duivert NL avatar image
Duivert NL answered ·

so you dont want the mppt's to deliver surplus to the grid?

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bernhards avatar image bernhards commented ·
No. I only want that the MPPTs load the battery. Then they can just wait. Therefore I want, that the Multiplus2 doesn't load the battery so that the energy of the other AC PV inverters (hoymiles for example) will go into the grid. So the idea is, to have a loooong charging time of the MPPTs instead of getting the battery full in some hours because most of the energy is from Multiplus2 + the other AC PC inverters.
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Duivert NL avatar image
Duivert NL answered ·

ok,

have you tried scheduled charging? i used to use that for a charging "window" during daytime

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mondeoman avatar image
mondeoman answered ·

You could set the Grid Setpoint to a very large negative value, a bit larger than you AC PV power, e.g. set "-10000W" if you have 8 kW AC PV.

Then the MultiPlus 2 will not take power from the AC-IN to charge the battery, it will let the AC PV to export as much as possible.

Also make sure that "Export DC-coupled PV" is disabled in ESS Settings.

And when you want to re-enable charging from AC PV surplus, then set Grid Setpoint to a low value (e.g. 50W or whatever you normally use).

You could make a NodeRed flow on your GX Device to automate this setting based on the Forecasted PV energy for the day.

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nickdb avatar image
nickdb answered ·

What about using node-red or MQTT to set /Device/DC/0/MaxChargeCurrent to 0 (if it is allowed) or a low value. This will allow the system to work as normal but prevent/limit AC charging.

IIRC it's the same parameter can be set via VC app or VEconfigure.

screenshot-2024-04-29-at-165034.png

Not tried this myself, maybe it works.


screenshot-2024-04-29-at-165034.png (48.9 KiB)
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pwfarnell avatar image pwfarnell commented ·

There was that discussion a month back about this setting not sticking because what you update is a live value in RAM not the saved setting and other processes such as DVCC could over write your setting from Node Red.

See

https://community.victronenergy.com/questions/271884/set-maxchargecurrent-to-0-within-node-red-works-bu.html

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nickdb avatar image nickdb ♦♦ pwfarnell commented ·
I though as much as there is a "current" value that fluctuates, it is also not listed on the official register.
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bernhards avatar image bernhards commented ·
MaxChargeCurrent would limit both, Multiplus2 (OK) and MPPT (NOK).


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nickdb avatar image nickdb ♦♦ bernhards commented ·
Not necessarily this parameter which seems to be multi specific (it matches the limit set on the inverter itself) but as pointed out, it seems to vary under DVCC control so can't be statically set.
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jetlag avatar image
jetlag answered ·

Did you try the proposal from @MondeoMan? This sound like it could solve the problem.

I have the same situation and will try it as soon I have enough solar power comming in the next days.

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jetlag avatar image jetlag commented ·
Ok, this does not work. Setting a negative grid setpoint will force the MP2 to discharge the batteries in moments where the AC coupled PV can't deliver...
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bernhards avatar image
bernhards answered ·

I have implemented it in Node Red by setting the DVCC Max Charge Current to the Amps the MPPT delivers (+50W). Together with the forecast.solar and some safety functions (JK BMS max voltage and battery temperature). In case of bad whether conditions the Multiplus2 is used, too. Works pretty good

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dutchsolarfreak avatar image dutchsolarfreak commented ·
Could you share your nodered flow?
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palom170 avatar image
palom170 answered ·

Hello, I am really so sorry for my bad English. What you want to do is possible using an assistant called control limit charge or similar.

It uses the aux what you chooses and when you close the contact it doesn’t charge. It is configurable in the assistant.

Have a look to that assistant. You can start using the default values.

Try it!

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