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Fresh from the market: system stability through renewables and storage systems

Stability enters a new era thanks to momentary reserve from renewable sources and storage: Momentary reserve is essential for maintaining a stable electricity grid. In the future, it won’t have to come solely from conventional power stations or transmission system operators. Instead, it can be sourced via market mechanisms – and the technical standards to enable this have now been defined.

Momentary reserve refers to the automatic and instantaneous release or absorption of energy by systems when there are power imbalances in the grid. This stabilises grid frequency and prevents disruptions such as widespread blackouts, thereby securing system stability. Until now, momentary reserve has primarily been provided by large conventional power stations and transmission grid operators. Going forward, battery storage systems and inverters used in renewable energy installations can be developed into grid-forming inverters – a key technology for ensuring secure grid operations in a future powered by renewable electricity.

What’s more, momentary reserves will soon be able to be procured via market-based mechanisms, making them more cost-efficient. This also supports the development of new technologies such as grid-forming inverters and unlocks further potential for providing momentary reserve.

^{Framework now in place: Federal Network Agency and Forum Network Technology/Network Operation publish guidelines}

At the end of April, the Federal Network Agency (BNetzA) laid down the rules for the market-based procurement of momentary reserve. At the same time, the Forum Network Technology/Network Operation (FNN) within the Association for Electrical, Electronic & Information Technologies (VDE) adopted the corresponding technical requirements. This establishes the framework for grid-forming inverters and a market-driven approach to momentary reserve. The FNN brings together manufacturers, grid and plant operators, as well as academic experts.

Transmission system operators are required to begin procuring momentary reserve services from January 2026. These steps represent major milestones in the System Stability Roadmap issued by the Federal Ministry for Economic Affairs and Energy (BMWE), which is guiding the secure operation of the grid and the introduction of grid-forming inverters.

A pioneering example of this is the Blackhillock project in the UK – a 300 MW/600 MWh storage facility, the first phase of which has been in operation since March. Among other things, it provides momentary reserve and strengthens grid stability. Key components come from Germany.