"REGIOlink" concept for regional grid support – first implementation already underway

Kempten, May 2025

With its “REGIOlink” model, green flexibility has developed a practice-oriented and cooperative concept for regionally grid-supportive operation of large-scale battery storage systems. While terms like “grid-supportive” or “grid-neutral” are currently widely discussed, a uniform and regulatory clear definition is often missing. This is exactly where the white paper (in German) by the Research Center for Energy Economics (Forschungsstelle für Energiewirtschaft, FfE) comes in: it provides a sound framework for classifying the operating modes of battery storage – with a focus on their impact on the grid, rather than on a specific control instrument. green flexibility is now taking the next step: an existing battery storage project is serving as the first reference installation in which key components are already being tested.

“While the industry continues to debate terminology, we aim to provide solutions and concepts,”explains Christoph Ostermann, CEO and co-founder of green flexibility. “We are already operating one of our storage projects using elements of the REGIOlink model. Initial results regarding operational behavior and integration into grid operation will soon be visible and shareable.”

Core of the concept: flexibility calculation

The goal is to ensure the economic viability of storage projects while simultaneously meeting regional grid requirements. Instead of blanket restrictions, concrete, data-driven control corridors are developed that also allow for a quantitative flexibility assessment. This makes it possible to identify exactly those hours in which feeding in or withdrawing energy helps relieve the grid – without unnecessarily limiting the system.

The REGIOlink implementation components include:

• Technical determination of grid-relevant operating modes based on regional grid data

• Coordinated processes via interfaces, rules, and schedules

• Contractual agreements with grid operators

• A live dashboard that enables full transparency over storage operations

  
  

The model can be implemented by grid operators without additional effort. green flexibility takes over coordination, technical design, and ensures that all relevant information is bundled and presented in an understandable format.

Economic viability remains part of the solution

“Of course, grid-supportive operating modes involve certain limitations – and that can potentially mean lost revenue for us as operators. But we are ready to take that step. What’s important is creating balance. We need fair, remunerated models and the regulatory framework to scale these solutions,”says Christina Hepp, Director Strategy at green flexibility. A key issue remains the lack of regulatory foundation. “The technical feasibility exists, but the legal framework is still missing. That’s why we are working together with grid operators to develop practical options for contractual and market-based solutions.”

Battery storage debate falls short

“In all the discussions about operating modes and grid impacts, we must not forget: battery storage systems are and will remain one of the most important building blocks for grid stability and the energy transition. To label them generally as grid-stressing misses the bigger picture.” – Christoph Ostermann, CEO green flexibility.

Download Whitepaper

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Attachment – Technical and regulatory classification

Rule-based definitions for future-proof grid integration

As part of the REGIOlink concept, green flexibility relies on clearly defined terms regarding the grid impact of battery storage systems.

These definitions relate to the actual impact of an operating mode on the power grid and are meant to provide guidance wherever local grid constraints require adaptation within the grid connection process. What matters is the contribution to the grid situation and the associated costs. 

The terms are technology-neutral, not tied to specific market roles or control instruments, and provide a transparent basis for fair, grid-related solutions.

The classification should only apply where grid constraints actually exist.

Screenshot from the white paper “Grid-Compatible Expansion of Large-Scale Battery Storage” by FfE e.V.

Grid-stressing

An operation that places additional demands on the grid in a specific situation, potentially leading to grid expansion needs or increased grid costs.

Grid-neutral

An operation that adjusts in such a way that – despite existing grid constraints – no additional costs for grid expansion arise, thereby helping to avoid further grid-related costs. 

Grid-supportive 

An operation that actively reduces grid load beyond neutrality and thereby contributes to lowering grid costs.

Important:

• A grid connection in accordance with §17 EnWG does not automatically imply that a storage system is grid-stressing. Grid impact is location-dependent and results from the actual operating behavior – not from the paragraph of the EnWG.

• Storage systems that are operated in a particularly market- and system-supportive way often behave grid-compatibly – general assessments are therefore not helpful.

• §11a EnWG is a call for tenders, not a definition of grid-supportiveness. 

REGIOlink makes this classification operationally usable – and lays the foundation for fair, transparent, and economically viable solutions in dialogue with grid operators, without legitimizing blanket restrictions.