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ayoub-rahmouni asked

Is there a minimum power of the battery bank for a Victron Energy Multiplus inverter/charger?

Hello, I hope you are well. I am Rahmouni Ayoub a PhD student engineer and I work on microgrid systems. One of our objectives is to realize a laboratory prototype that will contain a photovoltaic emulator that will produce a power of 3kWp connected to the AC bus via a photovoltaic inverter brand "Fronius", a group of batteries with an inverter charger "Victron energy" and other backup sources. According to the rule of the factor 1.0, the inverter charger must have a minimum power of 3kW because our photovoltaic source is 3kWp. but in our case since we use a photovoltaic emulator and even the load is a programmable load so we can simulate our day in some minutes. For this we don't need a battery capacity equal to the one used in a real model (that is to say we need a capacity of about 100ah maximum for our prototype). So my question is, is there a problem if I use a low capacity compared to the one used in real conditions with a 3kW inverter charger? (the capacity in real conditions is about 400Ah/24V).

Thank you very much!

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Alexandra avatar image Alexandra ♦ commented ·
@Ayoub Rahmouni

Usually minimum is 1:1 or the 3kw divided by the system nominal voltage to give an amperage, then a battery with bms to match.

If you are modelling with lead acid based systems, each victron inverter has a recommendation for the size bank. But it is also usually one that can sink the full amps at its c rating.

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sharpener answered ·

The purpose of the 1:1 rule is to prevent over-voltage when the grid and/or a load is suddenly disconnected and there is nowhere for the PV power to go except into the battery, until the Multi can shut down the PV inverter using frequency control.

So if with your programmable load and photovoltaic emulator you are confident you can ensure this situation does not arise, then you may be able to get away with a smaller battery than recommended.

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ayoub-rahmouni avatar image ayoub-rahmouni commented ·

Merci beaucoup

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