albert-strumpler avatar image
albert-strumpler asked

ESS, AC PV, "Switch as group", why?


I'm planning a near-future Victron installation which is going to look like this :

3 x Quattro II 48/5000 for 3-Phase AC + Cergo GX

I already have a Fronius Primo 8.2, but I'll change it for a Fronius Symo 8.2 as it is too powerfull for only 1 Quattro.

The goal is to have an ESS Assistant running on these, so I'll be grid-connected and the Fronius is connected on the critical-loads side (AC-Out1).

I already searched a lot on the Forum, Webinar and Online Training, and found this respons already :

BUT, I still don't understand the need and utility of the "switch as group" function for ESS or PV inverter support Assistant.

- In an ESS system, the communication between Victron and Fronius is already through LAN/Ethernet, as the Frequency is already determined by the Grid, so if there is too much power from PV, there is no need for Frequency Shifting, right ?

- With PV inverter Support Asssitant, why can't the Frequency not be shifted if "switch as group" is disabled ?

Why do I need it disabled ? For two reasons actually :


For example, I have 6kW produced from Fronius on 3 Phases so 2kW each. Now I have consumers on one phase that I can not split on two or three phases (EV Charger, big power Kitchen tools), so what happens is that I would have a load of 5kW (2kW direct from Fronius + 3kW from Victron). If the other to phases have no consumers, that would mean that one Quattro is Inverting and the other two Quattros are Charging (2x2kW). BUT if I understood correctly, this is NOT possible if "switch as group" is enabled. What happens in that case ?


I would love to put a one-phase Generator (only for grid blackout) on the master Quattro, so that he is Charging and the other two Inverting. Again NOT possible with "switch as group" enabled. Still, it should be enabled so that I can use ESS (or PV inverter support) for the AC coupled PV. Solution for that would be to buy a 3-Phase Generator, but if I can avoid it...

So my main question is why this "switch as group" function is so important for ESS or PV inverter support Assistant, can't it be left aside as communication goes over LAN ?

Dealers are a little overwhelmed by that kind of question, so I'm contacting the experts here, how would you solve that situation ?

@mvader (Victron Energy)

@Johannes Boonstra (Victron Energy Staff)

We could also communicate over phone or E-mail but I thought your response would interest the Victron community.

Thank you for reading until here, I hope you understood, if not, just ask ;)

MultiPlus Quattro Inverter ChargerESSAC PV Coupling3 phase
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2 Answers
Alexandra avatar image
Alexandra answered ·

@Albert Strumpler

Simple answer is it is complicated.

They are switched as a group so they can phase compensate and be synchronised and controlled better.

You are talking about phase regulation as well. They can regulate as individuals and a group if that is how you set it.

The system can charge on one phase and discharge on another at the same time.

The simplest way to have a single phase charge from a generator is to have another inverter that just charges from. (And that way your system will also always have a spare that matches your current setup)

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albert-strumpler avatar image albert-strumpler commented ·
Thanks a lot for your answer Alexandra. I'm relieved now. I'll see what I'm going to do about the generator.
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albert-strumpler avatar image
albert-strumpler answered ·

I may have been a little too complicated.

To simplifie, my question is : In an ESS system, what happens when the Quattro on L1 needs Inverting (More Load than Solar) and the Quattros on L2 and L3 need charging (More Solar than Load) ? Are L2 and L3 just going to feed-In so that all unit are Inverting ?

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