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MPII with ESS and AC coupled Fronius Primo on AC Out 1 - which grid code ?

Hi everyone,

I'm running a MPII with an ESS and 2 AC coupled inverters, see scheme:


In the red dotted rectangle you see the latest extension with a Fronius Primo.
As far as I understand I should be able to power backup loads and feed the battery with PV power with the Primo even when grid is gone - which is the objective.

The question is, to which grid code I should adjust the Primo.
At the moment, I use "DE1F - < 4,6kW constant cos phi" because this is the recommendation in the Fronius manual. It also seems to be obvious, because normally the Primo is connected with the grid by the MPII.

But, here: the advice is to use "MG50" Does this only apply the micro grids (island) or also to my configuration ?

I also want to register the extension to my grid operator (not yet done, but I applied for it), and as far as I know he can made a grid code mandatory.

Another thing is, that at the moment the meter information will be gone when grid is gone. It's because I read out the meter of my grid operator with an optic reading head and a rasperry Pi. But this Rasperry is powered from the grid, so it will stop working when grid is gone.

I'm happy about any comments and recommendations.


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Mike Dorsett avatar image Mike Dorsett commented ·
The MG50 probably only applies to microgrids, where the grid frequency is often used to control PV output - this cannot happen on grid situations.

I would also look at powering both PI's directly from DC, as this then gives the control system an uninterrupted supply.

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