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josecokem asked

Multiplus II + MPPT is the same as a solar inverter (fronius, deye etc...)?

I really do not fully understand the Victron ecosystem, if I pair a Multiplus II with a Victron MPPT... is this the same as a solar inverter like the ones from fronius, deye etc.. etc..? why then people add the Victron always to a normal ongrid system with other solar inverters instead of using the MPPts attached to the panels with the Multiplus II? So the solar DC will come to the MPPT and this to the Multiplus II, that will send some of the power to the batteries and other to the house grid in sync with the Big Grid... am I mistaken something? This could be so newbie question but I have research a lot and have not found any explanation? Why people expend more money on a solar inverter then if you can use the Multiplus II this way?

Multiplus-II
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ajmacleod answered ·

Some people have existing AC-coupled PV arrays (with Fronius etc inverters) which they want to add battery storage and/or another PV array to and so they use a MultiPlus to tie it all together.

Lots of other people (me included) just use a MultiPlus with PV panels and an MPPT charge controller with a battery as you describe and it generally works very well. One crucial point is that the MultiPlus based system requires a battery, whereas other inverters may not. The Victron system is extremely flexible though and can incorporate and manage several sources and several electrical loads, with or without a grid connection.

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seb71 answered ·

Why people expend more money on a solar inverter then if you can use the Multiplus II this way?

Usually it's less money for the entire system in the case of PV inverters/grid-tie inverters, because you don't need a battery (which is quite expensive). But if grid goes down, your PV-inverter will also turn off.

why then people add the Victron always to a normal ongrid system with other solar inverters

To still have power in case of grid blackouts and to use energy from the Sun during the night (energy from the Sun which was stored in the battery during the day).

instead of using the MPPts attached to the panels with the Multiplus II?

If you want to sell energy to the grid operator or you have a very big energy consumption (as AC) during the day, usually it's more efficient with a PV-inverter (which directly converts high voltage DC power from PV into AC power, without stepping down the high PV DC voltage to low battery DC voltage and then stepping the voltage back up during conversion from DC to AC ).

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josecokem answered ·

If you want to sell energy to the grid operator or you have a very big energy consumption (as AC) during the day, usually it's more efficient with a PV-inverter (which directly converts high voltage DC power from PV into AC power, without stepping down the high PV DC voltage to low battery DC voltage and then stepping the voltage back up during conversion from DC to AC ).


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So with Victron all the energy from the panel will always go first to the batteries and then converted into AC? Can Multiplus II convert the energy needed for the house on the fly and just put the remaining on the batteries? Or is always Mppt-bateries-AC, if so this is probably is worse for the batteries


I understand the batteries DC are 48v so the conversion to ac will be a bit worse than the 300v of an array, but this is not as important as the battery gets hammered every time the energy enters trough the mppt.

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seb71 avatar image seb71 commented ·

So with Victron all the energy from the panel will always go first to the batteries and then converted into AC?

Not necessarily through the battery, but at the battery voltage. The inverter is powered from the MPPT and/or from the battery.

The MPPT takes power from the PV array in form of DC at high(er) voltage and low(er) current and converts it in power still as DC, but at low voltage and high(er) current. There is some loss of power in this conversion, but minimal.


Can Multiplus II convert the energy needed for the house on the fly and just put the remaining on the batteries?

Not quite like you wrote. The inverter converts the energy needed for the house "on the fly" but the extra solar energy (if there is any) is stored in the battery directly from the MPPT, not by the inverter. The MultiPlus inverter can charge the battery with energy from the grid, if you want.

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