Multiplus II continuesly loading power from grid

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fred-38 asked Jun 7, '24

Multiplus II continuesly loading power from grid

Hello,

I just setup a PV system with 2 Multiplus 5k in parallel, a MPPT, PV, LiFePo4 battery and the Cerbo Gx. I do not have power meter yet, using internal one of the Multi.

I enable ESS but not DVCC. I disable the feed in.

I see that the multiplus is getting about 50wh all over the day from the grid to supply home load, even if the battery is full and/or sun is shinning.

That means I would pay 1kWh every day which is about 5 to 20% (average 10%) of my daily consumption.

I also see that when heavy load starts running (heater, oven, ...) the grid also delivers a good part of the peak current still about 10 to 20%. Again PV and battery can afford that load.

(Red is the grid)

Is such grid power consumption normal? or did I mistake a setup somewhere?

Thank you for your help

Best regards,

Fred

Multiplus-II grid

1717765643459.png (8.1 KiB)

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Answer 1 · 2024-06-07T14:33:09Z

Duivert NL answered · Jun 07 at 02:33 PM

What is your grid setpoint?

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Answer 2 · 2024-06-07T15:28:52Z

fred-38 answered · Jun 07 at 03:28 PM

Hi,

I set in Cerbo Gx / Settings/ ESS / Grid setpoint (well Point de consigne du reseau, in french ... ;) ) at 50w.

Is this setup for max feed in Grid but also but power in from Grid? Could I change to 20/10 or even 0W?

Br,

Fred

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Answer 3 · 2024-06-07T16:23:24Z

sean answered · Jun 07 at 04:23 PM

Lowering the set point may improve your current small continuous grid use, however you will not be able to stop your system using an amount from the grid when a large load is turned on simply due to the speed at which the inverters ramp up their output to meet the large load, you will also see an amount of export when the large load is switched off - again due to the speed at which the inverter/s ramp up/down

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Answer 4 · 2024-06-07T16:34:23Z

nickdb answered · Jun 07 at 04:34 PM

DVCC should be on.

Parallel systems are less efficient, the setpoint is also affected by the accuracy and quality of the wiring.

Lower the setpoint as suggested. Check the inverters are well balanced, this will affect the experience.

A clamp meter is best for this, else there are node red flows that can help.

Alternatively, disconnect from grid unless absolutely necessary. There is an assistant for this, or script the system to switch to invert only.

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Answer 5 · 2024-06-07T19:10:01Z

fred-38 answered · Jun 07 at 07:10 PM

Hi all,

Lot of nice feedbacks and guidances! Really appreciate! Thanks

About glitches, I was thinking about the inverter speed. Thanks for the confirmation.

I lower the setpoint, says 20 and see how it will work Then I fine tune in a way or the other. I feel setpoint reduction would increase current spike either in magnitude and/or duration. Working as a kind of reference for the internal inverter architecture. But I could be wrong.

I will check the wires, sure they are identical DC & AC, but not measured during on a large current for a heavy load. I hope for no surprise ;)

I need to read again DVCC chapter to clean up its setting. Its activation is on the todo list, only pending reception of a BMS - Cerbo adapter. I may enable it ealier ;)

I would keep the Grid connected. But keep the script idea somewhere in mind.

Br,

Fred

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