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pedaaa avatar image
pedaaa asked

Victron 1:1 rule

i have a question on the Victron 1:1 rule again:

What is the exact Limit for AC-Power output of a PV-Inverter on a 3phase Multiplus II 48/5000 ESS system.

Reading through the Victron Docs, it seams, that "15kW" is the max. allowed PV-invertor output, if connected to AC-Out1 of all 3x Multis.


But my grid supplier requires me to feed in with some reactive power with factor 0,9 cos phi.

So i need grid settings with CosPhi 0,9.

In this case, the 15kVA PV-Inverter max. (apparent power) output is actually only 13,5kW active power with 1,5kW reactive power.

Is this already the max. allowed PV-Inverter power output?


Or is the stated limit meant as an "active power" limit?

If so, i could increase the PV-Inverter power to 16,67kVA -> which will provide 15kW active power with 1,67kW reactive power.

What do you think?

Is this OK? or would this exceed the 1:1 rule limit?



Multiplus-II
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2 Answers
marekp avatar image
marekp answered ·

@Pedaaa

The grid requirements have no influence on the 1 to 1 rule.

The "rule" limit the AC-coupled PV inverter power to the max Victron because such PV inverter cannot be more powerful than Victrons ability to take energy to charge battery in case the grid is not present to take the feed and loads are zero.

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Paul B avatar image Paul B commented ·
Just for clarity here - The Max Grid tie PV input for Each phase cannot be more that 5,000 Va in your case.
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pedaaa avatar image pedaaa Paul B commented ·

thanks Paul!

so for my setting of 0,9cosPHi, with 3x Mulitplus II 48/5000 my limit is:

max. 15kVA PV-Inverter output, which is 13,5kW active power with 1,5kW reactive power.

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marekp avatar image marekp pedaaa commented ·

@Pedaaa

What PV inverter you have that you can select PF other than 1?

My Fronius always produces with PF=1.

screen-shot-2022-07-28-at-90929-am.png

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screen-shot-2022-07-28-at-90929-am.png (39.7 KiB)
pauldeegan avatar image
pauldeegan answered ·

This is a very good question that requires an answer. There is the 1:1 rule, but there is also the minimum battery capacity rules for AC coupled systems.


Inverters like Fronius can be set for a maximum output power within their PROFI settings. This way you can reduce a 5kW inverter to whatever you like to meet the design rules for Victron AC coupled systems.


You cannot do this with Enphase micro inverters, but you can change the Power factor. For instance, you can set 0.8 PF which will make a 5kW group of micro inverters only output 4kW of real power.


Question: Is this method of derating the PV inverter to fit within the design rules acceptable? What is the effect on the system of 0.8PF PV inverters? More audible noise? anything?


An answer from someone in the know would be greatly appreciated.


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mw-solar avatar image mw-solar commented ·

This is very interesting. Did you ever get an answer to this?

I have a 48/5000 with 10x 440w panels on a 5kW Solis string inverter.

Trying to find out if the 1:1 rule is 5kW or 4.4kW.

I also am not aware you can change the output power of the Solis, so the PF concept is interesting

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