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aquacheck avatar image
aquacheck asked

Multiplus-II does not charge on low mains voltage

Hi Community.

I have an unusual problem (2 actually). Running MP-II's coupled with Fronius Primo. Modbus TCP control with Cerbo. (edit, for clarity the Fronius is on the OUTPUT of the Victron)

Living with very unreliable grid, so I have set the mains voltage very wide (down to 180V disconnect, 200V reconnect on a 230V grid).

First issue I see is the MP-II will not charge the batteries when the mains goes below about 200V. Worse still: it exports all the solar and only a very small trickle to the battery. SOC limit set well above current SOC. limits are turned off. Also tried scheduled charge, but seems to ignore that.

Second is: when the voltage is just below 180V (disconnected, and voltage stays below the reconnect voltage) it holds the Fronius in Zero Export (like its expecting to connect, but the voltage does not pass threshold). I have checked it does not shift the output frequency, so it must be either pausing coms or throttling the Fronius. Just sits there indefinitely and depletes the batteries. Fronius set up MG50 according to victron recommendation.

Any one else have this situation?

Multiplus-IIFroniusmicrogrid
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Paul B avatar image Paul B commented ·
have you updated to the latest firmware and then the lattest assistants
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Alex Pescaru avatar image
Alex Pescaru answered ·

Isn't Fronius an AC coupled inverter?

Meaning, as long as it doesn't see a "reliable" grid, it doesn't function/export?

And that grid below 180V (second issue), could be an unreliable grid for Fronius, so it my be a Fronius decision to not export...

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aquacheck avatar image aquacheck commented ·
Hi Alex, yes it is, but in this case i follow the Victron setup for microgrid, meaning the Fronius will not see the grid until Victron closes the relay. So no the Fronius in this case sees the 230V from the Victron. Victron (cerbo) definitely shuts down Fronius and keeps it shut down indefinitely in while in that limbo state state
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