Missing power consumption of Victron system

Hi,

We are using a Victron system which includes a battery and PV. We have the following components:

Cerbo GX Gateway
MultiPlus-II 48/3000/35-32 VE Bus
Pylontech battery
SmartSolar Charger MPPT 100/20 48V

We are reading out the power values of these devices using modbus, however we notices that the total powers don't add up to zeros and we can't figure out where this power in consumed. We read the following registers:

AC Consumption L1

817

Grid L1

820

PV power

789

Battery Power (System)

842

Our system is only connected to one phase. When we subtract the sum of the PV, battery and AC consumption and subtract from the Grid we always get a non-zero value between 20-30 W. We are operating the battery at powers of the order of 100-200 W. Since the power loss of the inverter and slef consumption of the system should be much lower, we were wondering which part of the system could consume this amount of power.

Does anyone have an idea what could contribute to this additional power consumption?

Please let me know if you need additional information.

Thanks in advance,

Finn

2 |3000

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Alexandra ♦ commented · Jun 27, 2023 at 01:19 PM

Power factor. And wiring /heat losses.

Sometimes using the VA readings give you a better understanding of what is going on.

Is the battery system reading pylon sent values or ve bus values

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finn-1 Alexandra ♦ commented · Jun 27, 2023 at 02:45 PM

Thanks, you mean reading out the VA with modbus as well?

I am reading the battery power register provided by the system, I am not sure if the system gets these values from the Pylon or VE bus. According to the documentation the power loss due to the inverter should be around 12 W in this power range

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Matthias Lange - DE ♦ finn-1 commented · Jun 27, 2023 at 04:42 PM

12W is the zero load power.

The efficiency is depending on the load type and how much load it is.

Can you make a screenshot from the VRM dashboard? That's easier to read IMO.

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finn-1 Matthias Lange - DE ♦ commented · Jun 28, 2023 at 07:48 AM

I found the power dissipation of the multiplus inverter here: https://www.victronenergy.com/upload/documents/Output-rating-operating-temperature-and-efficiency.pdf Do you know if other documentation about energy losses and efficiencies?

Here is a screenshot of the VRM dashboard. As you can see about 40 W is not shown here and is consumed/lost somewhere in the system.

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1687938365158.png (53.3 KiB)

Matthias Lange - DE ♦ finn-1 commented · Jun 28, 2023 at 08:02 AM

That's an efficiency of around 86-87% that's ok-ish IMO.
The Multi is running at just 11-12% load.

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finn-1 Matthias Lange - DE ♦ commented · Jun 28, 2023 at 01:55 PM

Thanks, we also noticed that the lost power stays at about the same level after the setpoint on the grid power has been changed from the above value back to zero. At this moment the PV power was zero as well. Do you have an idea what could cause this since the battery consumption also becomes much lower when the setpoint is set to zero?

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