‘We’re hardly producing any power’: Can Europe’s solar boom survive a cloudy winter?

Europe risks entering its first ‘dunkelflaute’ of the year as cloudy weather dampens the continent’s solar boom and sends energy prices soaring. ADVERTISEMENT ADVERTISEMENT Solar, which has been described as a “shining star” of the transition away from fossil fuels, is one of the quickest-to-install and cheapest forms of energy in the world. In the right conditions, it can cost as little as €0.024 to produce one unit of power via solar panels – far outperforming coal, gas and even wind. It has already saved the EU €42.9 billion in avoided gas imports since the beginning of the war on Iran, which broke out on 28 February. It also helped stabilise the grid in the summer when back-to-back heatwaves triggered a spike in cooling-related electricity consumption. But Europe’s prolonged period of cool, cloudy and windless weather pose a serious problem. Can solar power perform in winter? A dunkelflaute – German for ‘dark lull’ – is a term used to describe an extended period when wind and solar power generation are low or non-existent because there is not enough wind or sunlight. It typically occurs from October through February in Northern Europe, exacerbated by short daylight hours, heavy cloud cover and fog. This coincides with increased energy consumption across the continent, due to chilly temperatures triggering demand for heating. Multi-day dunkelflauten are rare, but such an occurrence pushes Europe’s energy grid to rely more heavily on expensive backup generation such as natural gas. According to Bloomberg forecasts, German day-ahead power prices for Thursday 29 October were above €300 a megawatt-hour, about double the average in October, with hourly rates hitting above €500 for the evening peak. ‘It’s extremely disheartening’: Home solar output dips On an individual scale, households with solar panels are also noticing a spike in their energy bills. One UK resident who has 12 solar panels installed on their roof with a combined capacity of 6.36 kW tells Euronews Earth that on Wednesday (4 November) the panels only produced 10.90 kWh of solar – leaving them to rely on the grid for an additional 27.40 kWh of energy required. On Thursday (5 November), when their city was overcast for the entire day, the home generated just 2.40 kWh of solar, and imported 20.60 kWh. This is despite having an 11.52 kWh home storage battery that is charged at night on an off-peak tariff to discharge in the day when electricity consumption increases. Cloud is expected over the weekend and well into next week, meaning many Brits will be generating significantly less solar than they have during the summer. “We’re hardly producing any power,” the resident, who wishes to remain anonymous, tells Euronews Earth. “It’s extremely disheartening to see we’re importing so much energy when we have spent thousands on a solar system. However, we know that the panels will start to perform better when the clouds clear.” Hydro steps in for solar’s dips Of course, it is no surprise that solar produces most of its electricity in the summer months. In the EU, solar’s share of electricity generation hit 25.4 per cent in June – but in October this dropped to just 13.2 per cent. Of course, solar relies on daylight opposed to heat - meaning homeowners with rooftop panels will still produce power even on cold days. According to green energy supplier Good Energy, home solar systems in the UK can still generate around 25-35 per cent of their annual output in winter, which it says "provides a nice cushion for winter bills". A dip in solar production also tends to coincide with increased generation of hydropower – which started to rise in the EU last year from October. Solar is also able to help offset some of the electricity spikes caused by heatwaves, following a sudden need for space cooling, such as air conditioning and fans. According to energy think tank Ember, during the late-June heatwave this summer, daily electricity demand rose by up to 28 per cent in Italy, 23 per cent in Hungary, 14 per cent in France and 13 per cent in Spain compared with pre-heatwave days. It says that as heatwave-driven demand increased, solar was the only major power source to perform “better than usual”. Compared with other days in June and July, average daily solar generation during the heatwaves was 17 per cent higher in France and Hungary, five per cent higher in Spain and the same in Italy. A typical UK home with rooftop solar generated enough electricity to power an A/C unit for five hours per day during the hot spell, a separate Ember analysis found. At the same time, water-intensive forms of energy such as coal, hydropower and nuclear struggle during heatwaves – as scorching temperatures and lack of rainfall increase cause prolonged periods of drought. In August, Poland was forced to reduce output on its coal-fired power plants, which require massive amounts of water for cooling, following critically low water levels in the Vistula River. The move temporarily removed 1.3 GW from Poland’s power system, enough to power more than one million average households. This is around two per cent of the country’s current energy capacity.