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florianro avatar image

ESS: Basic Understanding for Factor 1.0 rule and 3 Phase PV Inverter

Hello,

I couldn't find the answer to my question in the forum, so I'd like to ask it here:

I'm talking about an ESS Scenario where I can use Phase 1 as a Backup if the grid fails. (One Multiplus-II between Grid and Phase-1 Loads).

I have a Fronius Symo 5.0 and a Multiplus-II 3000. So I'd like to install 1 phase of my fronius PV on AC-OUT just in case the Grid fails. But as far as I have understood I cannot do that because the PV Inverter delivers 5KW and the Multiplus-II can only handle 3 KW.

But what I do not understand is the following: How does the PV Inverter split the energy delivered from the PV Modules on the 3 phases? And what's the maximum load that's deliverd on one phase? Let's say phase 1 is on AC OUT of the Multi, phase 2 and 3 are on AC In side. So in case of a grid failure: would the PV Inverter put the entire power on phase 1?

So let's say I add a 2nd Multiplus-II. Then Factor 1.0 rule would be OK. Phase 1 and 2 of the PV Inverter would be on AC OUT, Phase 3 on AC IN side. How would the power be deliverd from the PV Inverter in case of a grid failure? Would it deliver all power on Phase 1 and 2?

thanks,

Florian



Multiplus-IIFronius3 phasefronius and victron
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Hi

On 3 phase inverters the load is split evenly among the 3 phases so each phase output is only 1.6kw per phase. You will need a Mulitplus2 on each phase to balance it correctly on the AC out, if the Fronius is on the input then you can have one mulitplus.

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daryl avatar image
daryl answered ·

What do you hope to gain by putting 1 phase of the Symo behind a Victron? The Symo will not operate unless all 3 phases are running so there is no point even attempting to do this (even if Victron do support such a configuration, which I highly doubt)

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Michael Schmidt avatar image
Michael Schmidt answered ·

To be faster than the question :)It is also not posible to operate the Symo on a single phase (3xL1)

the Fronius checks the 400V beetween al phases :)

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florianro avatar image
florianro answered ·

Allright, got it, thanks. I'd like to use the Battery on one phase as backup, but I was wondering if I can somehow still use the PV energy from the fronius for Charging...

thanks,

Florian

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Hi

Yes the Victron will take a load reading from the incoming mains via a current CT or it's energy meter and decide if enough power is flowing to the grid and direct that power through the mulitplus to to charge the batteries only when PV power flowing. So when the loads are importing power, no power will flow to the batteries etc.

As the CCGX or raspi controller takes care of all the using the ESS function.

As i have a similar system but single phase with a Fronius and Victron.