This summer, Europe is baking. Record-breaking heatwaves are sweeping across the continent. You might think this would be great for solar power, and in many ways, it is. Solar panels are churning out more electricity than ever before. Yet, many homes are seeing their electricity bills jump, sometimes doubling or even tripling. It’s a puzzling situation: lots of sun, but high prices, especially when the sun goes down.
June 2025 was a standout month for solar energy in the European Union. Solar power plants generated an impressive 45 terawatt-hours (TWh) of electricity. That’s 22% more than the same time last year, a new record. Countries like Germany saw solar production hit peaks of 50 gigawatts (GW), covering between 33% and 39% of the nation’s electricity needs. Solar energy, with its near-zero production cost, truly shines during the day.
The Nighttime Crunch
The problem kicks in when the sun starts to dip. Those extreme temperatures, often above 40°C in places like Portugal, Spain, France, and Germany, drive up electricity demand. Everyone’s air conditioning is running full blast. This increased demand doesn’t magically disappear when night falls. According to a recent report from Ember, daily power demand during June’s heatwave jumped 14% in Spain, 9% in France, and 6% in Germany. High demand means higher prices.
But there’s another twist: the very heat that boosts demand also cripples traditional power plants. Nuclear power stations, for example, rely on vast amounts of river water to cool their reactors. When river temperatures get too high, the cooling systems become less effective. This forces plants to reduce their output or even shut down. France, with its extensive nuclear network, has been hit hard, seeing capacity cuts across many units.
Bełchatów, in Poland, is Europe’s largest coal power plant and one of the biggest worldwide. Located in Bełchatów, Łódź Voivodeship, it has an installed capacity of about 5,472 MW. It uses locally mined lignite (brown coal).
It’s not just nuclear plants feeling the heat. In Poland, coal-fired power plants are struggling with cooling issues. Italy even experienced blackouts on July 1st, likely due to overheating power cables. So, just when electricity is needed most, the traditional sources are faltering.
France is Europe’s largest nuclear power producer. With about 56 reactors in operation, over 60% of its electricity comes from nuclear. Germany has no active nuclear power plants; their complete shutdown was finalized in April 2023. Spain has 5 operational plants (7 reactors) and plans a gradual shutdown by 2035.
The Storage Puzzle and The Price Gap
Here’s where the real headache starts. We have plenty of cheap solar power during the day. But we don’t have enough ways to store that energy for when the sun isn’t shining. Think of it like trying to save water from a waterfall when you only have a teacup. When solar production drops at dusk, and demand stays high due to the heat, grid operators have to turn to more expensive power sources. This usually means firing up natural gas plants or other fossil fuel facilities.
This imbalance between day and night causes dramatic price swings. We’re seeing daily price “spreads” as high as €400 per megawatt-hour (MWh) in Germany and €470/MWh in Poland. It’s this sharp spike in evening prices, not the average daily cost, that makes your electricity bill so painful. The clear message? It’s no longer enough to just make cheap, renewable energy. We need to figure out how to manage it. Investing in more battery storage or pumped-hydro facilities would let us buy cheap power at noon and sell it when prices surge in the evening.
Currently, Portugal has around 160 operational solar photovoltaic parks, with approximately 45 having over 5 MW capacity, totaling about 3.9 GW installed (2023 data). The first five months of 2025 already set a new record, with installed capacity doubling to 1,555 MW and solar accounting for 16.8% of national electricity consumption in May.
Connecting the Dots
Improving energy connections between European countries is also vital. The heatwaves didn’t hit everywhere at once. Peaks in places like Lisbon and Madrid happened on a Sunday, while Paris saw its peak on a Tuesday, and Berlin on a Wednesday. Stronger interconnections would allow countries with a solar surplus, like Portugal, to share that cheaper energy more effectively with their neighbors. This would help even out the demand and reduce those costly evening price surges.
So, while Europe is enjoying sunny, record-breaking days for solar power, the lack of smart management, storage solutions, and better grid connections means we’re still paying a steep price after the sun sets. The next big challenge for our energy grids isn’t just generating clean power, but making sure we can use it whenever we need it.