Belgian power prices spike twentyfold in hours

Belgian and Dutch wholesale electricity prices spiked in near-perfect parallel on 18 June, rising from about €19/MWh at 1pm to nearly €446/MWh and €467/MWh respectively by 9pm (EU Energy Belgium, EU Energy Netherlands). Some Belgian reports placed the peak at €550/MWh, though that figure likely reflects a different market layer, like rapid balancing trades, rather than the standard daily benchmark (Elia). The precise number matters less than what produced it. Europe's electricity system can now deliver very cheap power at noon and very expensive power at dinner, on the same day, through the same wires.

How €19 becomes €446

Europe's wholesale market works on a principle called the merit order: generators bid to supply power, the cheapest get dispatched first, and the last plant needed to meet demand sets the price (known as the clearing price) paid to all accepted sellers (OECD). Solar and wind bid cheaply because their fuel is free. Gas plants bid higher because they pay for fuel and carbon permits.

At midday on 18 June, abundant sunshine flooded Belgium and its neighbours with cheap solar, pushing prices to the floor. By evening, solar mechanically disappeared. Cooling demand from a hot day stayed. Wind was weak across Europe, covering only around 10% of electricity demand (WindEurope). The system suddenly needed gas plants to fill the gap, and gas set the clearing price for the whole market (Montel).

This is the "duck curve" in action. Residual demand (what's left once solar and wind are subtracted) dips at noon and rears up in the evening. The steeper the curve, the more expensive the evening becomes. And it is getting steeper as solar capacity grows without matching growth in storage, flexible demand, or cross-border connections that could move cheap midday power to when it's actually needed.

Who actually paid

Households on fixed-price contracts are buffered: their supplier has already hedged expected consumption, and one bad evening doesn't change the monthly bill. The cost sits on the supplier's books and surfaces later, through tariff revisions, only if spikes become frequent.

Households on dynamic tariffs, contracts where the energy component tracks the hourly market, felt it directly. Dutch consumer platforms showed a retail peak of about €0.83/kWh around 9pm, roughly eight times a normal evening rate (Overstappen.nl). Anyone running an air conditioner or charging an electric vehicle at that hour paid the spike in full.

On the producer side, the arithmetic flips. Generators already running cheaply (nuclear, hydro, any remaining wind) received the same high clearing price, earning a windfall on electricity that cost them almost nothing to produce. Solar producers, ironically, missed the party: they generated most during the hours when prices were lowest.

A continent-wide pattern

The Belgian spike is part of a continent-wide pattern. The European Commission's 2026 analysis found that fossil fuels still determined electricity prices roughly 50% of the time in 2025, down from about 70% in 2020 but still powerful in tight hours (European Commission). ACER (the EU's energy regulator) identified widening daily price spreads as a structural feature of the transition: more very cheap hours and more very expensive ones (EMI/ACER).

Spain, where renewables supplied 62.3% of electricity in early 2026, still gets duck-curve evenings when heat and low wind coincide (REE). Poland lost roughly 1.4 TWh of renewable output to grid constraints, cheap power that was generated but couldn't reach demand (PAP/PSEW).

Marginal pricing is working exactly as designed: it dispatches the cheapest generation first and signals when the system is tight (Eurelectric). But the signal is getting louder because the physical system, storage, demand response, cross-border capacity, has not kept pace with the renewable build-out. Europe tracks installed solar and wind capacity with great precision. The metric that matters more, and that almost nobody publishes in real time, is usable flexibility by hour and zone: how much cheap midday energy can actually be stored, moved, or shifted into the evening. Until that catches up, summer evenings like 18 June will keep repricing what the energy transition actually costs.