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2026 FIFA World Cup
17JUN

Same wind, two prices: solar sets gap

3 min read
10:21UTC

German day-ahead peaked at €187.30/MWh at 05:00 UTC on 31 July with wind at 3.4 GW. At 10:15 UTC on 29 July, wind sat at the same 3.4 GW and the price printed zero.

SportAssessed
Key takeaway

Identical wind produced €187 and zero six days apart; midday solar explains the gap.

German day-ahead reached €187.30/MWh at 05:00 UTC on Friday 31 July, with onshore and offshore wind at 3.4 GW⁠1. At 10:15 UTC on Wednesday 29 July, wind sat at the same 3.4 GW and the price printed €0.00 to minus €0.06/MWh. Two prints, one wind level, and roughly €187 between them.

Solar output separates the two prints. Germany has installed enough solar capacity that around midday in July it covers most of the load left over once wind, nuclear imports and must-run plant are counted. That leftover is residual load: the slice of demand the market has to price by dispatching something dispatchable, which in Germany means a gas plant. At 10:15 there was almost no residual load to price. At 05:00 there was, and no solar to meet it.

This desk asked last week whether German power would snap back above €110 the next time wind fell toward 3 GW with TTF near €58. It did, by a wide margin. But we wrote the mechanism as wind alone, and that was wrong in a way the 29 July control print makes plain. The snapback is a night-time event, worth roughly a fifth of the daily hours, not a whole-day repricing. The negative quarter-hours France and Germany both posted on 25 July and the €187.30 print of six days later sit on nearly identical wind, and only the solar leg separates them.

The correction matters for anyone reading a wind forecast as a price forecast. Germany cleared €195/MWh on 30 June on the year's lowest wind week, but that episode combined weak wind with a heat surge lifting demand into the afternoon. As solar output falls through September and October, the hours when wind alone determines residual load widen from a pre-dawn block toward whole days, which is when a low-wind forecast starts to mean what this desk previously implied it already meant.

Deep Analysis

In plain English

Germany's electricity price can look wildly different at two moments with exactly the same amount of wind power being generated, because what matters just as much is whether the sun is up. During the day, solar panels cover much of the demand that would otherwise need wind or gas, keeping prices low or even negative. At night, with no solar at all, the same wind output leaves a much bigger gap to fill, and prices spike. So it is not wind alone that decides the price; it is wind combined with whether solar is available at that hour.

Deep Analysis
Root Causes

The root cause is not wind variability alone; it is the interaction between wind and the hour of day relative to solar output. At 3.4 GW of wind and full midday solar on 29 July, residual load, the demand left over after renewables, was low enough to clear near zero. At the same 3.4 GW of wind but zero solar at 05:00 UTC on 31 July, residual load was high enough to clear at €187.30.

This reframes the mechanism this desk previously described as a wind story: the binding constraint on German clearing price is post-solar residual load, and any model that holds wind output constant while ignoring the solar profile of the hour in question will misprice the night-time peak.

What could happen next?
  • Meaning

    German day-ahead price spikes are better explained by post-solar residual load than by wind output alone, which changes what should be modelled when forecasting price shape.

  • Consequence

    Storage, interconnection and demand-response assets that can shift consumption or supply into night-time hours capture more value under this framing than a wind-only model would suggest.

First Reported In

Update #31 · Caverns restart, 21 points short of November

Fraunhofer ISE energy-charts (redistributing Bundesnetzagentur SMARD under CC BY 4.0)· 31 Jul 2026
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