Cloudy and Windless Winter Could Force Europe Back to Oil and Gas

Europe is facing its first "dunkelflaute" of the year as cloudy weather slows the solar boom on the continent and pushes energy prices up. Solar energy, dubbed the "shining star" of the fossil fuel phase-out, is one of the fastest-installing and cheapest sources of energy in the world. Under favorable conditions, the cost of producing one unit of electricity using solar panels can be as low as €0.024, which is significantly cheaper than coal, gas, and even wind. Since the start of the war with Iran, which flared up on February 28, solar energy has already saved the EU €42.9 billion on unrealized gas import supplies. In the summer, it also helped stabilize the energy system when electricity consumption surged due to a series of heatwaves. But a prolonged period of cool, cloudy, and windless weather in Europe poses a serious problem. ## ## Can Solar Energy Work in Winter? "Dunkelflaute," which in German means "dark lull," is a term used to describe prolonged periods when energy generation from wind and solar is low or absent due to a lack of wind or sunlight. This typically occurs from October to February in Northern Europe and is exacerbated by short daylight hours, dense cloud cover, and fog. This coincides with rising energy consumption across the continent as cold weather increases heating demand. Multi-day dunkelflaute events are rare, but when they occur, the European energy system is forced to rely more heavily on expensive backup sources, such as natural gas. According to a Bloomberg forecast, electricity prices in Germany on the day-ahead market for Thursday, October 29, exceeded €300 per megawatt-hour, which is about twice the average for October, and hourly rates during peak evening hours rose above €500. ## ## "This is Extremely Disheartening": Home Solar Generation is Declining In the private sector, homeowners with solar panels are also noticing an increase in their energy bills. One UK resident, who has 12 solar panels on her roof with a total capacity of 6.36 kW, told Euronews Earth that on Wednesday (November 4), the panels produced only 10.90 kWh of solar energy, and they had to draw an additional 27.40 kWh from the grid. On Thursday (November 5), when it was cloudy all day in their town, the house produced only 2.40 kWh of solar energy and imported 20.60 kWh. This is despite the fact that the house has a storage battery with a capacity of 11.52 kWh, which charges at night on a discounted night tariff and discharges during the day when electricity consumption rises. Cloudy weather is expected over the weekend and for most of the following week, so many residents in the UK will generate significantly less solar energy than in the summer. "We are hardly producing any electricity," says a resident who wished to remain anonymous in a conversation with Euronews Earth. "It is extremely disheartening to see that we are importing so much energy, even though we spent thousands on the solar system. However, we understand that the panels will start working better when the sky clears up." ## ## Hydropower Insures Against Solar Shortfalls It is not surprising that solar power plants produce most of their electricity in the summer. In the EU, the share of solar energy in electricity generation reached 25.4 percent in June but fell to just 13.2 percent in October. Moreover, solar panels depend on daylight rather than heat, so rooftop system owners continue to receive electricity even on frosty days. According to green energy supplier Good Energy, home solar systems in the UK can still provide about 25-35 percent of their annual output during the winter period, which, as the company notes, "creates a decent cushion for winter bills." The decline in solar generation typically coincides with an increase in hydropower generation, which in the EU began to rise from October last year. Solar energy also helps to smooth out peaks in electricity consumption during heatwaves when the demand for cooling, such as air conditioning and fans, sharply increases. According to the energy analytics center Ember, during the June heatwave this summer, daily electricity demand increased compared to pre-heat days by 28 percent in Italy, 23 percent in Hungary, 14 percent in France, and 13 percent in Spain. They note that against the backdrop of rising demand due to the heat, solar energy was the only major source of energy that performed "better than usual." Compared to other days in June and July, the average daily solar generation during heatwaves was 17 percent higher in France and Hungary, 5 percent higher in Spain, and at the same level in Italy. A separate analysis by Ember showed that a typical home in the UK with rooftop solar panels generated enough electricity for an air conditioner to run for five hours a day during the heat. At the same time, water-intensive forms of generation, such as coal plants, hydropower, and nuclear energy, struggle during heatwaves as high temperatures and lack of precipitation lead to prolonged drought periods. In August, Poland had to reduce output at coal-fired power plants, which require vast amounts of water for cooling, due to critically low water levels in the Vistula River. This move temporarily removed 1.3 GW of capacity from Poland's energy system, enough to supply electricity to more than one million average households. This is about two percent of the country's current energy capacity.