Industry follows working hours. Households follow schedules. Heating follows weather. The result is a familiar shape: a morning ramp around 06:00, an evening peak around 19:00, a long overnight valley. Weekends sit lower because most factories are closed.

Demand is the most predictable thing on the grid; everything else has to chase it. It powers motors and processes, heating and cooling, household appliances, IT and data centres, and lighting.

Each day, an auction sorts power plants from cheapest to most expensive and switches on enough of them to meet the next day's demand. Solar and wind go first because they cost nothing to run. Nuclear and hydro fill in. Gas and coal sit on top.

The most expensive plant the market has to switch on sets the price every other plant gets paid. That's gas most evenings; in Poland, still coal. When wind and solar flood the bottom of the stack, the marginal price drops with them.

Surplus crosses borders every hour. A windy Denmark sells into Germany; midday Spain and Portugal into France; overnight Poland buys from Czechia. Bigger price spread, bigger flow, until the wires are full.

Cheap northern Norwegian hydro can't just flow to Italy. The power has to hop through three or four zones, and every hop runs through wires that other producers are trying to use too. When one of those wires fills up, the cheap power stops moving, even when the price spread is huge.

The same friction lives inside countries. In Germany, North Sea wind can't reach Bavaria's demand because new transmission lines haven't been built. Iberia is in effect an electrical island, with cross-border capacity at just 3% of its generation. New generators across Europe wait years in queue to connect to the grid.

Wind costs almost nothing to run once it's built: no fuel, no carbon. That puts it at the bottom of the stack alongside solar. A windy day pulls the wholesale price down across the whole system. Two fleets: 245 GW onshore across the continent, and 35 GW offshore in the North Sea. Offshore is only about 13% of installed capacity but generates closer to a quarter of total wind output, because wind at sea is faster and steadier. Both swing together on the same Atlantic pressure-system cycle of 1–3 days.

The cost of producing a megawatt-hour is the easy part. What each one earns when it does blow is the question that decides whether more get built. Every new gigawatt drives down the wholesale price during windy hours. So the next gigawatt depends on whether something can absorb the surplus: storage, flexible demand, or an interconnector to different weather. Or it gets built where the wind is different: the summer-peaking Aegean, the Mediterranean Mistral.

Solar runs on a clock: peak at midday, dark at night. Clouds change the amplitude, not the timing. Over 400 GW across the EU. Germany alone runs 117 GW (more than Iberia and France combined), and every European market has been adding capacity for five years. But 2025 broke the streak: the first year-on-year decline since 2016.

Midday is now the cheapest hour in sunny markets. Demand still peaks in the evening, but solar peaks at midday. The result: noon prices crash while evening prices stay high. The question is who absorbs the surplus. Batteries that charge for the evening, factories shifting production into the cheap hours, cross-border cables that ship the surplus where the sun isn't shining. All of them get more valuable as solar saturates more days. And wind helps too: its overnight and winter peaks fall in the hours solar can't fill.

Batteries are the natural partner to wind and solar. They charge when the grid has surplus, like windy overnights and sunny middays, and discharge when demand outstrips wind and solar and gas sets the price.

Cheap batteries are arriving just as the grid needs them most. Lithium-ion costs have fallen roughly 90% since 2010, with grid-scale battery packs now at ~€65/kWh (down 45% in 2025 alone). At scale, the fleet absorbs solar surplus at noon and softens the evening peak that gas would otherwise serve.

Almost none of these batteries are made in Europe. Lithium iron phosphate (the cheap, durable battery type) dominates grid-scale storage, and the supply chain is Chinese top to bottom; Korean firms supply most of the rest. Europe's own bet, Northvolt, collapsed in March 2025. China's CATL is now building Europe's largest battery plant, in Hungary. The buildout is happening on European soil; the supply chain is not.

Hydro is currently the only large-scale storage that can balance the system. Li-ion batteries do four hours; reservoirs hold months. When wind and solar push midday prices down, hydro waits and sells into the expensive evening hours. As wind and solar grow, hydro gets more valuable.

Hydro comes in two forms. Conventional reservoirs store rainwater behind a dam and release it once through turbines: a one-way flow. Pumped storage cycles water between two reservoirs at different heights, pumping uphill when power is cheap and releasing downhill when it's expensive, recharging like a battery. Pumped storage is where growth is happening: Europe has almost no suitable rivers left for new conventional dams.

Norway holds around 87 TWh of stored water, roughly half the continent's. Undersea power cables to the continent make it Europe's effective battery, which is why operators now watch Norwegian reservoir levels as an early-warning signal for drought.

Gas plants fire up when nothing cheaper can serve the load. Typically that's the evening, when solar fades and demand rises. The UK, Italy, Spain, the Netherlands, and Germany run gas as a meaningful share of evening supply.

Before 2022, most of Europe's gas came through Russian pipelines at locked-in prices. Since the invasion of Ukraine, the continent buys liquefied natural gas (LNG) on the global market. The 2026 Strait of Hormuz blockade is the live test: Qatari flows are blocked, and European prices are up roughly 35%.

Gas is no longer the volume-mover it was twenty years ago. Renewables and nuclear carry more megawatt-hours, and cheap renewable hours push gas plants out of the merit order more often. Many now lean on standby payments to cover fixed costs. But gas still sets the wholesale price in most evening hours, which means every other plant in the auction is now indirectly exposed to global LNG prices.

Nuclear plants generate steady electricity from controlled fission, running for months at a time before refuelling. Nuclear's value is its ability to run continuously.

The current fleet is mostly legacy, built between the 1970s and 1990s. France runs around 42 GW continuously, hour after hour, more than the rest of Europe combined. Germany completed its phaseout in April 2023, after gradually closing reactors since Fukushima in 2011. Italy and Sweden also closed reactors. The engineering expertise that built and operated all of this aged out with the fleet.

Nuclear is being talked about again. Poland, the Netherlands, Czechia, Slovakia, the UK, and France are planning new builds, motivated by energy security. But the economics are tough: renewables crash midday and windy-hour prices, and new builds take decades. Operators lean on government financial support.

Coal still anchors the evening stack in a handful of countries. Poland runs the largest fleet, and it remains the dominant fuel of the Polish grid. Germany carries a shrinking lignite block. Czechia, Bulgaria, and Romania hold smaller positions. The UK closed its last plant in September 2024. Western Europe is essentially out.

Coal used to anchor the evening stack across most of Europe. Now it anchors it in five countries. Renewables crashed its running hours; carbon pricing crashed its margin. Where it still runs, the wholesale price tracks the EU carbon price directly. Germany's exit is set in statute for 2038, with a review scheduled for 2030.

Coal's supply chain splits in two. Lignite is mined and burned locally because it's too low-energy-density to ship economically. Hard coal is mostly imported; Russia was the largest source until the EU banned Russian coal in August 2022, with the trade reshuffled to South Africa, Colombia, and Australia.