question

Hartmut Behrens avatar image
Hartmut Behrens asked

Still pulling from grid/feeding into grid, despite batteries full, solar energy available

Hi,


What can be done to remedy this situation:

- grid set-point at 50W, grid feed-in is switched off for AC And DC, but still power is being fed to the grid. In this instance I am charged money for illegally feeding power back - energy is being wasted.


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On the other hand, if I put the grid set-point to something like 300w, then power is being pulled from the grid despite plenty of power being available from PV. It should not be necessary to pull power from the grid. In this instance I am also being charged, but this time for pulling power, which is at least a bit better than the previous situation, where energy is being frittered away.


How can this be remedied ? Do I possibly have a faulty grid meter (ET112) that needs replacing ?


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ESS
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myden avatar image myden commented ·
Hi,


No news about that from the support ?

I have the exact same situation

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7 Answers
matt1309 avatar image
matt1309 answered ·

Hi @Hartmut Behrens

I dont know if everyone experiences this but my ET112 is not very fast (5sec delay). I see similar fluctuations in usage (on average it's usually grid usage of zero) but the time delay in ET112 updating the system seems to be the cause in some grid export and import.


Solutions I've seen online have been to swap grid monitoring et112 to CT clamp. In my setup the fluctuations aren't crucial as i can feed into the grid so I've not bothered (ct clamp is too far away in my setup)

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thanar avatar image
thanar answered ·

What if you set set-point to 200W? Does it zero-out the backfeed?

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Hartmut Behrens avatar image
Hartmut Behrens answered ·

The installer is looking into this. I recently upgraded from EasySolar-II + 1x5kwh battery to EasySolar-II + MultiPlus-II + 3x 5kwh batteries. I was told there is a significant divergence in the SW versions running on the EasySolar vs MultiPlus that could be contributing to the problem. The other issue they picked up is that the voltage between the different battery cells is not balanced.

I'll let you know if this situation still persists after the issues have been addressed.

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thanar avatar image thanar commented ·
An out-of-balance battery should have nothing to do with the set-point reporting.
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tom w avatar image
tom w answered ·

According the screenshots, it seems you are not using the ESS assistant. What is the "External control" device?

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Hartmut Behrens avatar image
Hartmut Behrens answered ·

Err, I think that was a "cosmetic" change introduced not too long ago. See release notes: https://www.victronenergy.com/blog/2022/09/13/venus-os-v2-90-generator-controls-in-vrm-remote-ve-can-rv-c-venus-os-large-and-more/

(Search for "external control")

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tom w avatar image
tom w answered ·

Thanks for the explanation,

I'm still on version 2.82 and I'm looking for a change list before I upgrade to a newer version.

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larsea-dk avatar image
larsea-dk answered ·

Isn’t the issue actually that the inverter is hardcoded to only change 400w per second? The meters I think react fast enough, but if inverters (easysolar or multiplus) is hardcoded to react slow due to the 400w/s change, you will get fluctuating feedin value if your solar fluctuates… i.e. due to clouds etc. I have a similar problem with this slow “reaction”, but this is more related to high fluctuating charge/discharge values of the battery, when battery is full.

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gerard-van-seventer avatar image gerard-van-seventer commented ·

You are right. But we have to realize that once energy has entered the "blue box" it has t go somewhere. If the batteries are full and there is not available demand in house than the only solution is to dump it on the grid (or overload the batteries).

I think in version 3.x there are some changes on the reaction time. We also have to realize that a slower process and dumping energy to the grid is safer for the inverter, batteries and everything connected to AC-out. It is a bit similar why the factor 1 rule exist.


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