question

vicky avatar image
vicky asked

How to avoid "Battery to Grid" ?

I pulled VRM kWh data to see results of the first full month Multigrid and PV Panels working.

PV Yield in total is 417kWh, looks OK.

However what I don't like is the ratio of Battery to consumer 62.6kWh vs. Battery to Grid 30.5kWh

Of course I don't want to use my expensive RESU battery to feed the grid.

How can I avoid this?

Txs

Grid Setpoint is 30W

multigrid
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5 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Try setting the grid set point to 0 W

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vicky avatar image vicky commented ·

Did so today,

txs Guy

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Paul B avatar image
Paul B answered ·

It maybe exporting to the Grid when the batteries are full.


more details of the site would be needed to advise on this.


maybe look some more on the VRM and turn some widgets on and look at all the info and see if the battery is in float etc etc

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vicky avatar image vicky commented ·

Txs Paul
here is the setup:
Multigrid 3000/48,Venus GX, LG Chem RESU 6.5 a total of 5.7kWp installed, ESS feed to grid excessive PV - free giveaway to the grid, so far.
Panels are split into three strings 3.4kWp (new) wired to ACout1. 1.8kWp and 0.5kWp (old) wired to ACin, one inverter each.

What I did to find the root cause of battery feed to grid:

Downloaded VRM kWh data of the month. Sorted by "battery to grid" and extracted the top six rows. Then downloaded the VRM detailed data and looked up the data for the time of the a.m. top six. Marked them and added data of two minutes before and after.

So I can see the minute where the most data went from battery to grid plus what happened two minutes before and after. However I can't find any strange behavior.
As I am still learning a lot, I would be happy to get your feedback, in case you are bored to death and have no other project to be done. Have a look at the Excel here

Mybe I am chasing phantoms...in any case I'll try to set the grid set point to zero as advised by Guy Stewart

txs



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vicky avatar image
vicky answered ·

After two weeks with grid set point zero - I checked the VRM kWh data again.
Ratio now is : Battery to consumer 30.16kWh, battery to grid 21.19kWh

So it became worse :(


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mihair avatar image mihair commented ·

Please set grid setpoint to 50 ... 70W. It will take some energy from grid but will never export any.

Another option is to install a diverter in front of your system. It will divert all exported energy into a resistive load. In my case, ACM heater (please see schematic below)



KR,

Mihai

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voinesti-ess.png (427.0 KiB)
vicky avatar image vicky mihair commented ·

I try gridpoint 60W now, will report back in two weeks

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vicky avatar image vicky mihair commented ·

@Paul B

@Guy Stewart (Victron Energy Staff)

Grid setpoint @ 60W since 12 days, still feeding battery to grid :o(

Grid setpoint Batt to consumer Batt to grid ratio
30W 62,6 30,5 0,49
0.0W 30,16 21,19 0,70
60W 26,18 11,41 0,44
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vicky avatar image
vicky answered ·

Is there anybody out there who is suffering from wasting precious battery capacity to the grid like me ?
Battery to grid is still between 45 and 50% compared to battery to consumers. (see above).

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vicky avatar image
vicky answered ·

So at the end of the year, the annual VRM portal result is: 245kWh Battery to grid :( what a waste
Also, if I calculate power into battery vs battery to grid and consumers I am missing 410kWh (34%)
Something is wrong or do I miss a point?


1579349210266.png (3.2 KiB)
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JohnC avatar image JohnC ♦ commented ·

Too late for me right now, but my guess is that this has something to do with some of your panels being on AcOut and some on AcIn. Gotta be a measurement thing..


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