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casper-van-zyl avatar image

Incorrect Energy Consumption Reported in VRM

I have a strange situation.

I have been using VRM very successfully for approx 8 months and actually made use of the reported consumption numbers to size the upgrade of my battery pack in order to store sufficient power to get through a night without having to switch to the grid.

This worked very well and with the larger battery I am getting the desired effect however, it seems that when I am not connecting to the grid at all in ESS mode my consumption is not reported correctly it seems to be in the order of 30% of the actual consumption. If I look at the SOC% changes it looks as if I am consuming the expected amount of power during the night but but it seems that in both the "Consumption" tab and the " System Overview" this is not reflected correctly. Interestingly we had a few overcast days not charging battery fully and now I notice that the consumption shown is again much closer to the expected numbers.

Just as an example:

Starting with a SOC of 100% on a 50kWhr battery pack I typically use 40-45% of charge during a normal night taking it down to approx SOC of 60% indicating the use of approx 20kWhr. Looking at the consumption numbers it would indicate the use of 6-7 kWhr during the night however the battery is down to 60% and its SOC correctly reported VRM. During the day it will charge 20kWhr into the battery showing the correct amount of power charged back into the battery.

Now I see that with the overcast days not running from the battery all night the consumption shown is as expected very close to the 20kWhr although part of the night it was using the battery in ESS but not right through.

Any suggestions on why this happens and what is going wrong.
I have a Victron system with 3 MPPT chargers and a 3 phase installation with 3 x 8KVA quattro's all connected to a Victron color control. Battery is a Blue Nova battery with a can bus BMS directly connected to the color control. All individual items communicate correctly with the color control and reported numbers looks correct.

VRM
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Do you have an energy meter? Do you have any loads on the input side of the inverters?

I am assuming all loads are on the inverters and thus no energy meter is required.

1 Answer
gherlt avatar image
gherlt answered ·

More or less the same here
https://community.victronenergy.com/questions/79411/vrm-monitoring-shows-wrong-data.html
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There is some systematic underreading and inconsistency between all the values between PV Inverter, "Discharge" and "Critical Load", not being connected to the grid, the values just don't sum up. The most funny thing is that even with no load connected the "critical load" is value rises with the value of PV production.
This is the current value, still on batteries only: 651W discharge, critical load 337
-9W PV Inverter. There is a huge mismatch ....
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1616709184533.png (30.0 KiB)
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