Dynamic ESS, weird behaviour when feeding back in to the grid

Q&A and troubleshooting
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Hi all,

I’m using a MultiPlus 48/5000 with a 17 kWh battery, 5×520 Wp solar panels, and a dynamic energy contract. I’ve enabled Dynamic ESS and overall it works well—buying when prices are low, selling when high.

However, I’ve noticed a problem:

When the system decides to export (e.g. 1.5 kW between 20:00–21:00), it sticks to that export power regardless of my actual load. For example, if I’m using 3 kW (e.g. oven and cooktop), it still exports 1.5 kW, causing 1.5 kW to be imported from the grid at the same time.

It seems the system doesn’t consider real-time consumption when exporting. Is this expected behavior? If so, are there recommended workarounds (e.g. Node-RED or Venus scripting) to prevent simultaneous export and import?

Thanks!

2

DESS works with an average battery percentage as setpoint. For example from 80% Soc to 60% Soc in 1 hour equals to 1.5kWh of energy. It does not “compensate” for own consumption, that is not how DESS is intended to work. This would also be impossible as some systems may have own consumption of 15kW at a certain time, while normally exporting 15kW to the grid. This would result in 30kW drawn from the battery in your preferred case.

3

Sounds like you are running on the release track of Venus OS?

That is a known Issue, and in the current beta version, DESS has received various modifications and new strategies - and one of them would exactly account for this issue, to allow a higher discharge during a scheduled selling - when loads demand for it.

If you like to give it a try, you could switch to the latest beta in the GX. (it is always possible to return to the release version if there are issues - mind it’s a beta release)

1 Like
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Thank you for the quick response, I have installed the beta version now :slight_smile:
And will check if behaves better.

Before updating I was looking in this topic on any updates regarding the DESS algorithm.
But could not find any other than:

v3.60~47
Dynamic ESS

* Improve how Dynamic ESS reacts when actual consumption or solar production differs from forecasted. For example when there is more solar then expected, the updated algorithm will in many cases use that extra solar power to charge the battery, even if that would exceed the planned SOC level for the current hour. Instead of feeding that excess solar back into the grid for a low price, to later have to buy it back at a higher price.

Guess many under the hood changes are not mentioned in the changelog? Or did I miss this?

5

Yes, that is right. Listing every (minor) change would produce a really big changelog.

But in some sence, this line describes your Issue:

  • DESS scheduled for 1500 sellpower, cause it expected consumption to be lower than that.
  • But then consumption was higher, causing unexpected grid-pull.
6

Yes indeed that is correct. Happy to hear that :slight_smile:

Thanks for the quick responses, did not expect answer/ solution this fast.
Have a nice evening/ day.