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Is June the new January? A summer peak in a winter-peaking grid
June 24, 2026
Archy de Berker<br>Co-founder @ Axle
Karl Bach<br>Co-founder @ Axle
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Power markets in Northern Europe are traditionally winter-peaking: grids are most strained during winter due to high heating demand. That changed this week: a European heat wave sent the European electricity system into overdrive and sent prices spiking.<br>On June 24th even GB, where air conditioning is still regarded with suspicion, saw power prices surge to their highest price in 18 months. The UK hasn’t seen a peak price outside of December or January since September 2021, when the first gas crisis began.
The Iran war (March 2026) caused a stepped increase in prices. Peak annual prices are typically December or January.So what's the story? Supply is unusually tight and inelastic; under marginal pricing, even a small, unexpected demand bump clears at a punishing price. June 24’s high prices are driven by a handful of factors which emphasize the growing complexity and interdependency of the European grid.<br>Demand is higher than expected<br>Evening demand is higher for June 24 2026 than for the equivalent day over the last 5 years. And this story is mirrored nearly everywhere across Europe, particularly in France:
This matters because GB and European power markets are increasingly coupled thanks to interconnection. These are the undersea cables that allow power to flow to and from the continent. Fluxes vary depending upon prices: high continental prices tend to pull power from GB generators, and vice versa. Changes in supply and demand on either side of the Channel can influence prices across the continent.
However: although demand is higher than we’d expect at this time of year, it’s not objectively high. It’s still far lower than the regular Winter peaks. But the important thing from the system’s perspective is that we expected demand to be high in January, and we didn’t expect it to be high in June.
It's vacation time for power plants<br>Power plants require regular maintenance. June is a good time to do it. But not this June.<br>In the UK, almost 15 GW of our 34 GW of Combined Cycle Gas Turbines (the main form of gas power plant) are offline. That’s 42%!<br>And we’re not alone: EDF also takes advantage of the expected early Summer lull to service their nuclear power plants. They’ve got ~29% offline for maintenance.
As climate change brings greater and greater unpredictability, we should expect this kind of mis-timed planned maintenance to become a bigger and bigger issue. Fortunately wind and solar don’t rely upon superheating steam, and require fewer prolonged maintenance periods.<br>In fact, soaring solar generation is one of the factors suppressing prices - the sharp rise in price around 7pm is linked to the sun going down, as Ember reported during a similar heatwave last year. We can see this in the demand profile for 24th June, which has a deep dip around 12 - this is embedded solar generation eroding demand before it hits the grid.
French nuclear takes a hot bath 🥵<br>Nuclear power plants require a lot of water for cooling. If the water that they’re using is hotter to begin with, they can’t dump as much heat, and so they need to run at lower capacity.
EDF has announced reduced output at four reactors along the Garonne and Rhône rivers (Reuters), where temperatures are tickling the 40s. This accounts for roughly another 2GW of capacity reduction on top of the planned maintenance already occurring.<br>Conclusion<br>Thanks to marginal pricing, small shifts in demand can have a big effect upon price. Generators with long maintenance windows can’t react to unexpected changes in weather conditions, and so supply can be sluggish to react to changes in demand. This supply-inelasticity produces price spikes like the one we’ve seen on June 24th 2026.<br>Our power systems need more flexibility...