One Year of FCA Experience: green flexibility Introduces a Blueprint for Clear Rules for Utility-Scale Battery Storage
Together with a grid operator, battery storage developer and operator green flexibility takes stock of 12 months of grid-neutral battery storage operations: a practical FCA Blueprint, alongside clear criticism of overly restrictive market approaches.
Current discussions in the market around FCA requirements for utility-scale battery storage are, in some cases, going too far. They are often overly restrictive, economically challenging, and, in some cases, not effective from a grid perspective. Rather than integrating battery storage into the energy system in a grid-compatible way, rigid or blanket requirements and restrictions on operational flexibility risk unnecessarily slowing down both the deployment and utilisation of battery storage.
Drawing on more than 15 FCA negotiations over the past few months — across a wide range of grid areas, including with LEW Verteilnetz, in Ostmünsterland and with VWEW-energie — we have gained valuable insights and practical experience into which provisions work in practice, where blanket requirements reach their limits, and how grid security, flexibility and economic viability can be better balanced.
Further valuable insights have been gained through the operational experience of the battery storage system in Immenstadt, in cooperation with grid operator AllgäuNetz. For around a year now, one of Germany’s first utility-scale battery storage systems operated on an FCA basis in a grid-neutral manner has been in operation there.
“Overly broad or overly restrictive FCA requirements ultimately do not serve the grid. They can prevent flexibility rather than enabling it to be used effectively. In our view, what is needed are proven, practical models that ensure grid security without unnecessarily limiting the role of battery storage in the energy system.” – Volker Wiegand, Managing Director, AllgäuNetz
These experiences have led to the development of a practical Blueprint, shaped by the real-world interaction between battery storage operators and grid operators.
The Blueprint is based in particular on dynamic power limitations, a full-load-hours-based restriction model, and the system-level management of balancing power. It combines grid stability, planning certainty and commercial flexibility, and follows a standardised, parameter-based approach that distinguishes between grid-neutral and grid-supportive operation. Restrictions are consistently aligned with the actual state of the grid.
“The proposals put forward by major distribution system operators illustrate that FCAs are still too often viewed as a means of restricting battery storage — rather than as an intelligent operating model for integrating storage into the grid in a grid-compatible way. As the role of battery storage in distribution grids continues to grow, its interaction with grid operations is becoming increasingly important,” explains Volker Wiegand, Managing Director of AllgäuNetz. “Shifting forecasting responsibility to battery storage operators is just one example of where current approaches fall short. Anyone seeking grid-safe, transparent and non-discriminatory power limitations must place this responsibility where the relevant grid data and system responsibility reside: with the grid operator.”
With the FCA Blueprint, green flexibility is presenting a field-tested framework for future FCA agreements between battery storage and grid operators. In the AllgäuNetz grid area, further utility-scale battery storage systems are expected to be connected to the grid in 2027 under this first-of-its-kind FCA framework.
[The battery storage system in Immenstadt is a joint project with Allgäuer Überlandwerk and was commissioned in June 2025. It has a capacity of 15 MW / 33 MWh.]
