August 2025 brought extreme fluctuations in the electricity market. In just one month, prices slipped below zero for 64 hours, marking one of the highest monthly values since records began. The persistently sunny days caused massive overproduction, while demand at times failed to keep pace. Germany has thus already recorded 465 hours of negative prices by the end of August, exceeding the previous year’s figure of 457 hours. (zfk: 02.09.25)
Sunshine pushes the electricity market to its limits
According to the German Meteorological Service, Germany recorded an average of 253 hours of sunshine in August. This makes the month one of the ten sunniest since measurements began. In Saarland and Lower Franconia, the figures were even higher, with up to 300 hours of sunshine. These exceptionally intense weather conditions led to overproduction and put pressure on energy prices.
Compared to the previous year, however, 2025 was slightly lower. August 2024 brought even more sunshine with 262 hours of sunshine and even recorded 68 hours of negative prices. This was four hours higher than the current level. However, the long-term trend shows that the electricity market is increasingly coming under pressure the more solar and wind power are fed into the grid simultaneously.
Solar Power Significantly Below Market Price
For operators of solar systems, earnings were particularly weak at the beginning of the month. While the average exchange electricity price in August was €76.99 per megawatt hour, solar power generated an average of only €39.43 per megawatt hour. This large gap illustrates how strongly energy prices for renewable sources differ from the general market value.
The particularly low revenues in the first week of August noticeably depressed the monthly average. The situation only eased somewhat towards the end of the month. This provided some relief for operators who refinance their systems on the electricity market. Nevertheless, the trend shows that fluctuations caused by overproduction pose a significant risk for investors.
Record negative prices approaching
The trend so far this year leaves little doubt: A new record number of hours with negative prices is likely to be reached by December. The figures already exceed the entire year of 2024. The massive oversupply of solar power is pushing energy prices down, while at the same time, more flexible demand would be needed to cushion the fluctuations.
The increasing frequency of negative prices highlights the structural problems in the electricity market. Without additional storage or controllable consumers, even more severe fluctuations are threatened in the future. While sunny months drive up overproduction, there is still a lack of sufficient adjustment in demand.
Market and operators under pressure
August 2025 clearly demonstrates how closely linked the weather, energy prices, and the electricity market are. Excessive hours of sunshine not only lowered the market value but also reduced revenues from solar power. As the number of hours with negative prices increases, the pressure on market mechanisms grows.
Whether storage technologies, more flexible consumption, or greater grid integration – solutions are urgently needed. This summer’s record figures show that overproduction can lead to extreme situations even more frequently.