The transmission system operators tender the required quantities of balancing capacity on the balancing energy market. As trustees of the balancing groups, the TSOs are required to call up balancing capacity as cost-effectively as possible in accordance with the working prices of the bids submitted. This requirement applies to both the automatic balancing of fluctuations ("automatic Frequency Restoration Reserve", or "aFRR" for short) and the manual balancing ("manual Frequency Restoration Reserve", or "mFRR" for short).
For both balancing capacity types and both control directions, the bids submitted are ranked nationwide in a merit order list (MOL) in the order of the energy prices and only the most favorable surcharges are called up in accordance with demand.