DESS Trading is buying from grid with solar overhead

Q&A and troubleshooting DESS
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Hi all,

I’ve been using Dynamic ESS (Trade mode) for a while now, and in most cases it works very well and the behavior is understandable.

However, today I noticed something odd:
According to the forecast, the system plans to buy around 1.8 kWh from the grid, even though there’s at least 2 kWh of solar excess available around the same time (clearly visible as PV → Grid in the energy graph).

Screenshot 2025-06-25 100133
Screenshot 2025-06-25 1001331137×924 39.8 KB

This raises a few questions:

  • Why isn’t DESS using the solar surplus instead of buying from the grid?
  • Is this just incidental behavior, or caused by timing mismatches or forecasting anomalies?

To me, PV is “free energy”, so using available solar to charge the battery or avoid grid import should always be the preferred strategy — especially when there’s no conflicting consumption demand.

No need to suggest “Green mode” — I’ve experimented with that in the past (up to v3.50), but the results were less reliable in my setup.
As long as net metering (salderen) is still active in the Netherlands, Trade mode remains the most logical and cost-effective option in my view.

Any insights are welcome — thanks!

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Hello @favado , welcome to the forum. You may want to read along with use here: Another Strange DESS behaviour - #13 by UpCycleElectric

I tend to agree with that statement. I seems to me that most recent DESS development has been focused on solar systems and self consumption in Green mode with less attention to Trade mode. I am testing with Node-RED flows to make Trade mode be more opportunistic in its buying decisions which makes it behave more in line with how I’d expect it to do. I too tend to believe the best economic performance (low cost, return on investment) is to be had with a well behaved Trade algorithm even with solar production added on top of that.

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