question

techsol avatar image
techsol asked

Fronius zero feed in - 2 Fronius inverters

I need Your help/advice.


We have client with single phase electric installation.

He has two Fronius inverters. Each inverter has connected 3.6kWp of photovoltaics.


We want to build him ESS on BYD and Multi Plus-II 5kVA.


1st Fronius will be connected to the input of the Multi (when there is no grid – inverter turns off).

2nd Fronius will be coupled on the output of the Multi (when there is no grid – inverter still works).


Client cannot feed Energy back to the grid.

Can we realise zero-feed-in function in configuration mentioned in above (scheme in the attatchment)?


If not can You give me any suggestions?

ESSLithium BatteryFronius
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2 Answers
Riaan Barkhuizen avatar image
Riaan Barkhuizen answered ·

Hi @TechSol

Assuming that you have Fronius inverters that are compatible with the Victron equipment I believe that you would be able to get such a system working.

I would have the master fronius connected to the AC-Out and the slave on AC-In. Under the PV inverters menu of the venus device you will be able to tell the venus gx where each inverter is connected. This would improve control during a grid-outage. You would have the ethernet control as well as the frequency shifting control working.

Both grid-tie inverters would have to be setup using the MG50/60 settings with a specific failover for when the one inverter disappears from the system due to a power outage etc.

When the grid is one the venus would be able to control everything nicely.

As far as I'm concerned you have not violated the factor 1 rule, unless both inverters are connected to AC-out.

Let me know how it goes, very interesting setup.

Best Regards

Riaan



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techsol avatar image techsol commented ·

Dear Riaan. Thanks for Your suggestions!

Best Regards

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laurentiupitran avatar image
laurentiupitran answered ·

here attached you have an 3 phase ESS system configured with ZERO INJECTION in second graph and first graph there is same period of time - one month- where you have used energy from grid and injected energy to grid , even is considered ZERO INJECTION.


monthly-0-injection.png (110.8 KiB)
grid-used-and-injected.png (165.3 KiB)
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Riaan Barkhuizen avatar image Riaan Barkhuizen commented ·

If you want to have absolutely zero feed in you may need to setup ESS to have a minimum consumption of say 100W as a set-point in place of the 0W target.

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laurentiupitran avatar image laurentiupitran Riaan Barkhuizen commented ·

hi,

there is not ZERO injection in this kind of regulator in ESS system; in practice, you can set any value that you want as consumption from grid, at the end of experiments you will feed the grid .....

both of pictures are made with 30 w injection in grid; more or less is coming critical as value injected on gird

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grid-injection.png (219.8 KiB)
grid-injection-exemplu.png (214.6 KiB)
techsol avatar image techsol commented ·

Dear Laurentin,

thanks for Your answer!

@laurentiu.pitran@gmail.com

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