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leonb avatar image
leonb asked

Fronius on AC IN or AC OUT

Hello All,

New to AC-Coupled systems and have been reading factor 1 rule etc. Some background..... Client owns a smallish shopping centre drawing around 275kWhrs per day, and does not have any big loads. We are doing a datalogging next week to confirm what inverter sizing etc. My question is as follows:

1. How do you decide to put the fronius on AC in Or AC Out. If on AC out, how does it charge the battery, or is that another clever thing Victron has done?

2. If on AC in, does factor rule 1:1 still apply?

3. If he does not draw very large currents as I expect, do I still need to keep the 1.5 x kWp rule in mind for battery?

Any help will be greatly appreciated.

Regards

Leon





GeneratorAC PV CouplingFronius
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Warwick Bruce Chapman avatar image Warwick Bruce Chapman commented ·

@LeonB where did you get the 1.5 rule from?

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leonb avatar image leonb Warwick Bruce Chapman commented ·

https://www.victronenergy.com/live/ac_coupling:start#minimum_battery_capacity

Here we go

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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @LeonB

The Victron equipment can charge from anywhere in the system (as long as it can see it).

Minimum battery sizing may still apply, it is best to follow the individual and specific recommendations of the battery manufacturer for sizing.

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Janek Plathe avatar image Janek Plathe commented ·

HI Steward, is the expression that the multiplus can charge from anywhere also applicable if i have an Fronius connected to the Multiplus II on AC input and MPPT`s on the DC side of the Multiplus... Would both sources be utilized/combined for charging if available?


greetings

janek

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petajoule avatar image petajoule Janek Plathe commented ·

Yes. The MPPTs are on a "DC bus" and as such are quite decoupled from the AC IN/OUT of the Multi.

The system therefore can utilize power sources on all three AC In and AC out and DC at the same time. The Quattro is very similar in that respect, except it has AC IN1 and AC IN2 and uses a priority scheme (IN1 over IN2) there.

We usually connect a Genset to Quattro AC In1, Grid to AC In2, Fronius to AC-Out1 (leave AC-Out2 alone) and of course MPPTs to DC bus.

And then watch the Quattros juggling. ;-)

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petajoule avatar image
petajoule answered ·

In general, the Fronius can be on IN as well as OUT. It depends on other parameters where you finally decide to put it.


If it's a new installation, AND if you do not want to feed in back to the grid, I would put it on OUT. The "1:1" rule applies (which is actually a N:1 rule if you have several Quattros/Multis).

If you can/want feed back to the grid AND if there are no outages or these aren't critical, AND you would have trouble to satisfy the 1:1 rule, I would put it on IN.

I'm not aware of any 1.5kWp battery rule for the battery. Must be a lead-acid thing. ;-)

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