Negative prices and solar energy

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superjerk asked May 2, '24

Negative prices and solar energy

Yesterday, energy prices plummeted to negative values for a span of 2 hours, reaching as low as -9 euro cents per kWh. During this period, it became economically advantageous to deactivate solar energy production and instead draw power from the grid to charge batteries. However, this course of action was not taken.

Only a minimal amount of energy was sourced from the grid, despite the potential benefits. I observed that my grid load consistently hovered around 0 watts, even when attempting to increase consumption by activating four 3200 W heaters. Surprisingly, this had no effect on the grid load, and the charging of batteries proceeded at a slower pace.

I possess four PV inverters connected via modbus, as well as a Victron PV Charger, all of which remained operational without any disabling.

I'm puzzled as to why I did not experience a maximum load from the grid during this period, which would have been the most financially rewarding option. Simply consuming the energy and receiving payment for it seems like a logical choice?

Dashboard at 14:24

Additional information from this day. Here you can see there was a minimum load from the grid.

dynamic ess

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Modifications Space

Node Red Space

Answer 1 · 2024-05-02T09:34:47Z

onur-b answered · May 02 at 09:34 AM

@superjerk ,

Thanks for this entry. I asked it in a different way under https://community.victronenergy.com/articles/270649/dynamic-ess-on-vrm.html, hopefully we will get an answer but I witnessed exactly what you described yesterday.

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Answer 2 · 2024-05-08T13:26:36Z

Jeroen Peters answered · May 08 at 01:26 PM

I have mentioned exactly the same issue in the main DESS topic with negative prices, solar curtailment and charging from the grid.

@Dirk-Jan Faber (Victron Energy) is this a known issue that will be fixed in a future VRM update? I expect more negative hours to come if the sun starts shining again over the next few months.

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Answer 3 · 2024-05-14T18:37:07Z

some-user answered · 3 days ago

Hello,

I have the same experience, overall I'm very happy with DESS but negative prices aren't handled correctly. What I see every time when there are negative energy prices is that the intention is good -> loading the battery (partly) from the grid. But this never plays out because the battery is already full once the happy hours are reached. Also I would expect that even if the battery is full the system would switch over to draining power from the grid during happy hours. This also doen't happen. I attached a screenshot "before" and "after".

Above the intention to benefit from negative prices is show,

But is never does, battery is already full way before happy hour.

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