question

warick-wrx avatar image
warick-wrx asked

victon multiplus 1:1 rule

So I understand that in an ideal world one needs to match their grid tie inverter size with multiplus size. Hence the term 1:1 rule. For example a 5000VA multiplus to a Fronius Primo 4.0 etc. But what about connecting say a 5000VA multiplus to a Fronius Primo 3.0. I can't see that the Multiplus whould be at risk of overload when loads are suddenly dropped form the Fronius. Its probably not an ideal setup as per the 1:1 rule but would just like to know if anyone is running anything similar and if there could be any issues.

Multiplus-II
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2 Answers
snoobler avatar image
snoobler answered ·

Nope.

https://www.victronenergy.com/live/ac_coupling:start#the_factor_10_rule

The max PV power must be equal or less than the VA rating of the inverter/charger


A 5000VA MP AC coupled to a Fronius Primo 3.0 satisfies the rule.



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Paul B avatar image
Paul B answered ·

If you go outside the 1:1 rule you void your warranty.


the below is ONE a ruff example of why.


the 1:1 rule applies as per the below example

if the multi is a 5000va and pv inverter is at 5000va and thus is charging your battery and suppling loads through the multiplus and then any excess is exported if the loads go down and the grid is dropped then all the 5000va from the pv is diverted to charge the battery, until the pv is told to derate, if the pv does not derate (ie the freq shift is not setup correctly ) then the battery would be overchargered


however if the pv was say 6000 then if the loads dropped and the grid dropped then the 6000watts would have to be diverted somewhere and the only place left is to the battery and then the multiplus's charging system would be overloaded and would burnt out or be damaged.


the freq shift is not instant and there is always a time lag

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