ONE YEAR OF FCA PRACTICE: A BLUEPRINT FOR CLEAR RULES FOR LARGE-SCALE BATTERY STORAGE
Together with the grid operator, battery storage developer and operator green flexibility looks back on 12 months of grid-neutral battery storage operation: an FCA blueprint developed from real-world practice — with a clear critique of overly restrictive market approaches.
AN FCA BLUEPRINT FOR THE INDUSTRY
Current discussions in the market around FCA requirements for large-scale battery storage systems sometimes go too far. They are often too restrictive, economically problematic and, in some cases, not effective from a grid-technical perspective. Instead of integrating storage systems into the energy system in a grid-compatible way, rigid or blanket requirements — as well as restrictions on operational flexibility — risk unnecessarily slowing down their expansion and use.
Over the past months, green flexibility has negotiated more than 15 FCAs across a wide range of grid areas, including with LEW Verteilnetz, in the Ostmünsterland region and with VWEW-energie. These negotiations have provided valuable insights into which provisions are practicable, where blanket requirements reach their limits, and how grid security, flexibility and economic viability can be better balanced.
In addition, further valuable insights have been gained together with the grid operator AllgäuNetz through the operational use of the battery storage system in Immenstadt. For around one year, one of Germany’s first grid-neutral large-scale battery storage systems based on an FCA has been in operation there.
“Overly generic or overly restrictive FCA requirements ultimately do not help the grid. They can prevent flexibility instead of making it usable in a targeted way. From our perspective, what is needed are practice-proven models that ensure grid security without unnecessarily limiting the systemic role of battery storage.”
Leandra Boes
Director Commercial Asset Management
Based on these experiences, a blueprint has been developed from real-world practice — built on the actual interaction between battery storage operator and grid operator.
The blueprint is based in particular on dynamic power limitations, a full-load-hour-based restriction model and the systemic control of balancing power. It combines grid stability, planning security and economic flexibility, and follows a standardized, parameter-based approach that differentiates between grid neutrality and grid supportiveness while consistently aligning restrictions with the actual grid situation.
“The proposals put forward by major distribution system operators show, by way of example, that FCAs are still too often understood in the market as an instrument of restriction — rather than as an intelligent operating model for the grid-compatible integration of battery storage. Against the backdrop of the growing role of storage systems in distribution grids, their interaction with grid operation is becoming increasingly important. Shifting forecasting responsibility to storage operators is just one example of where current approaches fall short. Those who want grid-secure, transparent and non-discriminatory power limitations must place this responsibility where the relevant grid data and system responsibility lie: with the grid operator.”
Volker Wiegand
Managing Director, AllgäuNetz
With the FCA blueprint, green flexibility presents a practice-proven template for future FCA agreements between battery storage operators and grid operators. In the AllgäuNetz grid area, further large-scale battery storage systems are set to be connected to the grid in 2027 as part of 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. 15 MW / 33 MWh — press release]
Our blueprint is intended as a practical offering for grid operators, municipal utilities and selected cooperation partners. The aim is to enter into dialogue, share experience and further develop possible approaches for future agreements. Interested partners from these areas are welcome to contact us via the form.