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szdan avatar image
szdan asked

Help me understand AC Output power

Hi fellow Victron enthusiasts.

I have some basic questions but being relatively new to it. Better ask the experts for their opinion here.

The setup is as follows:

3 x Victron Multiplus II 5KVA

1 x RS 450/200

1 x LIFEPO4 BMS 100Ah with 50A max charge and 100A max discharge
10.5kW Solar panels
1 x Victron Charging Station

- Grid feed in is allowed at max power and all components are connected to copper bus bars

What we find is that somehow the RS's output is quite limited. My question is could it be because of the battery size? In my head it shouldn't matter, right? If power is available the Multi's should consume it and inject it to grid or is there some other logic? (the grid is fine, it is not saturated).

Thank you.


Multiplus-II
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1234enough avatar image 1234enough commented ·
So you have 10.5kw of panels to rs450/200 (potentially 200A of dc charging) to a lifpo4 battery that has a max 50A capacity of charging.

If the MP2 have no loads, Where are you expecting power to go?

100A feeding 3 x 5kva mp2 seems very small, when Victron recommends a 200A fuse on one mp2 5kva

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szdan avatar image szdan 1234enough commented ·
Grid feed in is allowed and there is an EV station as well. My question was if for example the battery can habdle only 50A charge but there is a demand from EV station on AC output for 200A. Will the Multi's service this load or will they be limited to the battery charge value, as all going through the same bus bar?
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nickdb avatar image nickdb ♦♦ commented ·
It goes without saying, that system and battery config is horribly mismatched which will cause issues, as batteries aren't just about capacity, they have to buffer power fluctuations from solar as loads/generation varies. This is not a good design.


What do you mean by limited?

Can you provide charts? Details on PV layout?

What are you expecting?

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4 Answers
jetlag avatar image
jetlag answered ·

Did you activate the "Excess Feed-In" for DC without a limit in the ESS settings?

Please check in your remote console.

Regarding your question, - No, the battery should normally not block the excess energy to be pushed into the grid. When the battery is full, then the current into the battery will be reduced to almost 0A, and the excess is then taken by the Multiplus.

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Duivert NL avatar image
Duivert NL answered ·

how is everything connected (schematic?), how is it set up (ESS?) and what is your battery brand and size

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szdan avatar image szdan commented ·
Yes, ESS assistant is configured and Feed-In allowed. Have a look if it makes sense what I replied to comment above. Thanks
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Duivert NL avatar image Duivert NL szdan commented ·

Looks from your info you have 4.8kW off battery storage, you need at least 24kW of storage for 3x 5k multiplus in order to work properly…

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Kevin Windrem avatar image
Kevin Windrem answered ·

You can not feed into the grid unless you have a GX device in the system, plus several other critical configurations including a grid company that allows it.

Assuming there is something in the system that will limit battery charge and discharge to safe values, you would be limited to 1200 watts of consumption and 600 watts of charging. Compare this to 15,000 watts of inverter and 10,500 watts of solar.

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szdan avatar image szdan commented ·
Hi Kevin. There is of course a Cerbo and feed-in is allowed. The meter is two-way at grid point now. I just wonder if battery charge current can be the limiting factors for other consumers.
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guillaume-bossuet avatar image
guillaume-bossuet answered ·

If you activate de excess feed in be careful that de dvcc limit current charge ( 50a in your case ) wouldnt be respect...

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szdan avatar image szdan commented ·
Super. Thanks for making it more clear now.
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