question

feded00 avatar image
feded00 asked

Power management with Multi + Battery + MPPT tracker + cerboGX


I have a question concerning the scheme below, where I am planning to build an off-grid test bench for a battery (48V) connected to a Multi-II used as an inverter to power some AC loads and to an MPPT solar tracker managing the power coming from a PV array. We also consider to include a Cerbo-GX for monitoring purposes (e.g. reading data for our BMS, which runs on a PLC).


Specifically, is it possible to decide how much watts to put into the battery vs to power the AC load?

As an example: consider a PV generation of 1500W. Can I charge the battery with 700W and power the load with 800W? Is this doable via the Cerbo-GX controlling the Multi-II?


Many thanks in advance.


scheme-2.png


Multiplus-IIMPPT SmartSolarbatteryoffgrid
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1 Answer
Alexandra avatar image
Alexandra answered ·

@feded00__


You are offgrid.

The system will prioritise loads of the inverter over battery charging. In other words the solar powers loads, then left over production goes to charging. If your production is power than your loads it will pull the needed power from the battery (discharge) and solar.

You can as a consumer control your loads.

If you were on grid you could then choose where the solar was going and the grid would supplement the load if the solar amount you chose was lower than load. But then that is exactly what the Victron ESS assistant already does.

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feded00 avatar image feded00 commented ·
Thank you for the answer.


Do I need to enable DVCC to achieve this? If I understood it correctly, the parameter "Max charge current" of DVCC mode should take care of this.

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Alexandra avatar image Alexandra ♦ feded00 commented ·
Sorry I was editing and finished after you replied.


You could reduce charge current in DVCC but all that will happen is the mppt would throttle down to load + level of charge set. Which could make you produce less than is actually possible.

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feded00 avatar image feded00 Alexandra ♦ commented ·

Then, in case I want to exactly match the loads, without charging the battery (and eventually loosing some power from PV), I should set in DVCC mode the maximum charging current to 0A. Is that correct?


Otherwise, I can select the amount of amps going inside the battery by modifying this limit...and all of this should be doable via Modbus/TCP-IP, if I got it correctly.

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Alexandra avatar image Alexandra ♦ feded00 commented ·

I think that would work. I have never tried setting it to 0A in DVCC. But I have used it to reduce battery charging.


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feded00 avatar image feded00 Alexandra ♦ commented ·
All right, thanks. And to be sure, DVCC is still usable while being off-gride, correct? (while ESS only works when connected to grid).



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Alexandra avatar image Alexandra ♦ feded00 commented ·
Yes. DVCC works off grid.
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