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frankvdn asked

Can multiplus II optimize self consumption of PV AC generated energy in a 3-phase house

Schermafbeelding 2021-01-30 om 12.42.38.png

Wij zijn op zoek om onze zonnepanelen uit te breiden met een batterijsysteem van 20 kWh.
Onze solar installatie heeft 15000 Wp en zal ongeveer 12000 kWh / jaar produceren.
Ons verbruik ligt ongeveer bij 40 kWh per dag verdeeld 50% dagverbruik en 50% nachtverbruik.

We willen volgende functionaliteit :

1. backup en nood systeem in geval het net uitvalt voor een beperkte tijd (max 3à4 uur)
2. een optimalisatie van de eigenproductie voor zelfverbruik en, indien nodig, netvoeding te voorkomen

Kan de Victron Multiplus 48/5000/70-50 ons hierbij helpen en kan de victron in bijgevoegd schema ook aan zelfverbruik optimalisatie doen om het productieoverschot van onze zonneenergie overdag te consumeren s’avonds en s’nachts?

Wordt er rekening gehouden met battery-life voor de winterperiode waar we onvoldoende zelfproductie hebben om de batterij volledig te kunnen opladen? Wat doet de victron in dat geval?

Multiplus-IIESSAC PV Coupling3 phase
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3 Answers
frankvdn avatar image
frankvdn answered ·
Hi guys in English now :

We will complement our solar energy installation with battery system 20 kWh.
our solar 15000 Wp and will produce 12000 kWh / yearly

Functionalities required :

1. backup system in case of grid power failure
2. optimalisatie of the selfconsumption of the energy produced by our PV system and so to reduce the consumption of the gridpower

Can Victron Multiplus 48/5000/70-50 provide us with these requirements , the added scheme would be our setup at home?. The idea is to store te overproduction of our PV installation in the batteries at daytime so it can be used at night time to avoid as much as possible the need for gridpower.

Is their also a battery-life guard in the inverter, because in winter time our PV system will not produce enough energy to load the batteries , what does the victron offer to prolong the battery life?

Many thx for your feedback .


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frankvdn avatar image
frankvdn answered ·

Meanwhile , I found out the I will need 3 multiplus-es in my 3-phase house, correct?

additional , I 'd like to know how the multiplus-es decide when to start charging the batteries and when they decide that battery power should be used instead of grid-power? do they just look at the charge level of battery, when battery reaches 90% charged state (SOC) they start the consumption off the battery until DOD drops below 10% or 20%?

thx for your feedback

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alan avatar image alan commented ·

You don't need three, its more than possible to use a single unit.

The venus device (ccgx, venus, cerbo etc) monitors total power in/out and aims to keep the grid meter at 0w (or the set point), until the preset battery levels.

Watch the video in the first link, the second contains info about phase compensation.

In grid failure the system will backup the phase its on.

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bjorn-n avatar image bjorn-n alan commented ·

It is possible to use a single unit, if the solar panels/PV inverter are connected to the grid that is (i.e. not to the "AC load" side of the MultiPlus-II).

Although the components are identical, the way you connect them makes a big difference:

If the PV inverter is connected to the grid, the PV inverter will shut down if the grid fails.

If the PV inverter is connected to the "AC load" side of the MultiPlus-II, the PV inverter will keep working even if the grid goes down. Note however, the PV inverter power should not exceed the power of the MultiPlus-II.

If you want to avoid backfeeding PV energy to the grid completely, you will need as much MultiPlus-II inverter/chargers as you have peak PV production power. From a techical cool factor, that makes sense. It may not make financial sense though. And even with multiple MultiPlus-II, when the batteries are full, you will still feed into the grid...

In the end, the amount of MultiPlus-II inverter/chargers you need depends on the configuration you design/build and your goal. :-)

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jejochen avatar image
jejochen answered ·


The main goal of the ess system is to keep the main meter at 0.

The ess system can provide all you ask for.

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frankvdn avatar image frankvdn commented ·

Hello jejochen,

is it possible to program the multiplus so that it will only charge the batteries during the daytime when solar panels are producing an overcapacity of electricity? E.g. Between 10 am and 16 pm


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bjorn-n avatar image bjorn-n frankvdn commented ·

Yes you can. Mind you this is not an intelligent schedule. It does not take into account the effective power that is produced by the solar panels. It just starts charging the batteries at 10:00 every day and stops when at 95% State of Charge or at 16:00 (whichever comes first).


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