Secure system operation: Bundesnetzagentur confirms electricity grid reserve capacity requirements
Year of issue 2025
Date of issue 2025.04.28
The Bundesnetzagentur has today confirmed the grid reserve capacity requirements for winter 2025/2026 and winter 2027/2028.
“The grid reserve remains important for the time being to guarantee the secure operation of the transmission system. The grid reserve capacity required in the coming winter will be about the same as in the previous one,”
said Klaus Müller, President of the Bundesnetzagentur.
Lower forecast for grid reserve and redispatching requirements in 2025/2026
The Bundesnetzagentur has confirmed a total required grid reserve capacity of 6,493 megawatts (MW) for winter 2025/2026. This is a reduction of 7% from 2024/2025 (6,947 MW). The requirements for a winter further ahead are routinely identified as well. For winter 2027/2028, the required grid reserve capacity has been put at 6,525 MW.
The calculations for 2025/2026 also show that the forecast redispatching volume will be 17 terawatt hours (TWh) in the period, around 30% less than in last year’s analyses for 2024/2025 (approximately 25 TWh). This is particularly due to the progress made in expanding the grid, as well as methodological improvements. A decline in line with the forecasts will help to lower costs for redispatching measures and thus relieve the financial burden on network users.
Provision of grid reserve capacity
The great majority (5,149 MW) of the 6,493 MW of grid reserve capacity needed for winter 2025/2026 will be provided by German power plants. As in previous years, power plants in other countries will provide the remaining 1,344 MW (2022: 1,424 MW; 2023: 1,334 MW; 2024: 1,467 MW). The transmission system operators will issue a call for foreign power plant operators to express their interest in providing grid reserve capacity by mid-May. Transmission system operators’ contracts with foreign power plant operators are concluded in agreement with the Bundesnetzagentur.
Reserves for system stability
Grid reserve capacity is contracted to prevent overloading in the transmission system that occurs because of congestion. This is done by reducing generation in front of an impending congestion in the grid and at the same time increasing generation behind the congestion.
This mechanism, known as redispatching, is carried out in the first place using power plants that are active in the market. In certain situations, however, the active plant capacity is not sufficient to relieve the congestion. In such cases, additional grid reserve power plants are activated. The German grid reserve power plants are power plants that have been marked for closure but may not be shut down because they have been categorised as important for the system. These power plants may only be used when instructed by the transmission system operators and may not be operated in the market. The grid reserve power plants in other countries are contracted especially for this purpose. The costs for contracting and using the power plants are part of the overall redispatching costs and are refinanced through the network tariffs.
Congestion is being gradually reduced as the grid is expanded.
The transmission system operators presented their system analysis and the resulting grid reserve capacity requirements to the Bundesnetzagentur for evaluation on 14 March 2025. The determination of the grid reserve capacity is the final step in the Bundesnetzagentur’s evaluation process.
The report (in German) has been published at www.bundesnetzagentur.de/netzreserve.