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Glossary · Energy industry & energy transition

Flexibility register

flexibility register flexibility electricity grid distribution grid Aggregator Demand response

A flexibility register is a structured directory of generation units, consumption units and storage systems that can change their feed-in or electricity consumption over time. Besides name and location, it mainly records the characteristics that matter for use in the power system. These include the adjustable electrical power, the grid connection level, technical controllability, response time, the metering concept, availability and the communication interface. It also records the operator, the marketer and possible restrictions. In the draft European network code on demand response, such a system is called a Flexibility Information System (FIS). In technical literature, the two terms are often used synonymously.

The term belongs to the topic of flexibility, that is, the ability to adjust generation, consumption or storage over time. A register makes this ability findable, verifiable and attributable. Without such a directory, it often remains unclear which flexible resource exists at which connection, who may control it, how much of it is available and whether it is already committed to another task.

A flexibility register does not create flexibility itself and does not replace control technology. It is a data and allocation infrastructure. Its value only arises when the data are up to date and standardised and are linked to operational processes. A heat pump, a battery, an electrolyser, a cold store or a charging station may be technically flexible. However, it only becomes usable for grid operation, market participation or aggregation by third parties once its characteristics are known and permissible access has been regulated.

What information a flexibility register contains

The central parameter is usually the adjustable electrical power in kilowatts or megawatts. For storage, energy content in kilowatt-hours, state of charge, charging and discharging power and efficiencies are added. For controllable consumers, duration, frequency and the limits set by comfort or the production process matter. A heat pump can only shift its electricity consumption as long as the building stays warm enough. An industrial pump may perhaps only be interrupted if production does not suffer. A battery responds very quickly but is limited by its state of charge: a full battery cannot absorb any additional electricity.

The electrical location is equally important. For the wholesale market, a flexible megawatt-hour within a bidding zone is largely equivalent. In the distribution grid, by contrast, location matters. A unit behind an overloaded local network transformer has a different effect from a unit in an unloaded grid section. Registers therefore link flexible units to the grid connection point, the metering point, the voltage level and the responsible grid operator. The Norwegian pilot system, for example, assigns metering points to a grid location, a balance responsible party and a bidding zone. For groups of units, it records the power per substation.

A register must also separate roles cleanly. Owner, operator, supplier, aggregator, metering point operator, balance responsible party and grid operator may be different actors. Whoever can technically control a unit does not necessarily market it themselves. And whoever markets it is not automatically allowed to intervene in its operation. The register must therefore map responsibilities, permissions and changes, for instance a change of service provider for a controllable unit. Otherwise conflicts arise during activation.

The European framework: Flexibility Information System in the network code

At EU level, the concept is regulated in the planned Network Code on Demand Response. The first draft was prepared by the European Network of Transmission System Operators for Electricity (ENTSO-E) and the EU DSO Entity for distribution system operators. The Agency for the Cooperation of Energy Regulators (ACER) revised it and submitted it to the European Commission on 7 March 2025. The package also amends three existing regulations: the Electricity Balancing Guideline, the System Operation Guideline and the Demand Connection Code. According to ACER, it is intended, among other things, to simplify prequalification and strengthen cooperation between grid operators.

According to the proposed definition, a Flexibility Information System covers at least the following steps: the qualification of service providers, product prequalification, product verification and the grid prequalification of units and groups of units. It also records the transfer of controllable units between service providers. All of this applies to balancing energy and local services, and the data required for them are exchanged via the system. The draft provides for two organisational forms. Either each procuring grid operator runs its own system with a common access point, or a nationally designated entity runs a central system. The draft also distinguishes a module for controllable units from a module for service providers.

As to its legal status: an article in the CIGRE journal Electra from June 2026 reports that the Commission has not yet adopted the regulation. The network code is therefore so far a proposal and not applicable law. If it is adopted in the committee procedure and published in the Official Journal, it will apply directly in the EU Member States. Many details are then to be laid down through national conditions and EU-wide methodologies. Definitions and deadlines may still change until then.

An early example is the EuroFlex project in Norway. There, the data hub operator Elhub is developing a Flexibility Information System as a prototype. It deliberately relies on a central system in which both modules are combined. The rationale is that each controllable unit should only be registered once and that small grid operators should not have to run their own system. The project documentation expressly describes the system as a prototype and not as productive operation.

Situation in Germany

In Germany, § 14c of the Energy Industry Act (EnWG) obliges operators of electricity distribution grids to use a transparent, non-discriminatory and market-based procedure when they procure flexibility services for their grid. The specifications and standardised market products must be approved by the Federal Network Agency (Bundesnetzagentur). The Bundesnetzagentur can lay down exceptions, for example where market-based procurement would not be economically efficient. Grid-oriented control under § 14a EnWG for controllable consumption devices remains unaffected. In the paragraphs examined here, § 14c does not mention a separate, legally prescribed flexibility register. Such a register would, however, be an obvious technical basis for the procedures mentioned.

Distinction from market platform, grid control system and unit register

A flexibility register is not a trading platform. A platform brings supply and demand together, forms prices or organises tenders. The register clarifies beforehand which resources exist, whether they have been verified and under which conditions they can be addressed. Nor is it a grid control system, which monitors switching states, load flows and voltages during ongoing operation. The register sits at the level of master data, qualifications and permissions and supplies data to such systems.

It differs from the Marktstammdatenregister (German core energy market data register) in its focus on usable adjustability. That a photovoltaic system is entered in the Marktstammdatenregister says little about whether it can be curtailed, how fast it responds, who operates its interface or whether an activation would conflict with other obligations.

Why the register is becoming more important

In the past, flexibility came mainly from dispatchable power plants. With many wind and solar plants, heat pumps, electric vehicles, battery storage systems and electrified industry, a large part of the possible adjustment today lies in the distribution grid and behind individual house connections. These resources are small, scattered and often reachable only digitally. A grid operator can hardly plan with them if it sees them only as anonymous load. And an aggregator can only pool them if technical limits and rights are clarified.

The register helps with three tasks. It makes flexibility visible before it is needed. It supports coordination between transmission and distribution system operators, for instance when a unit simultaneously supplies balancing energy and is a candidate for local congestion management. And it can document whether a committed capacity was available and was actually delivered. The Norwegian pilot system provides a dedicated delivery verification process for this.

Typical misunderstandings

  • Registration does not create additional flexibility. A unit that is not controllable, has no suitable metering or cannot be activated for operational reasons does not become a reliable resource by being entered.

  • A register does not automatically resolve usage conflicts. If an aggregator wants to use a battery on the market and the distribution system operator needs it at the same time to avoid congestion, priority must be settled through rules, contracts and regulation. The register makes the conflict visible but does not decide it.

  • Data protection does not concern only households. The location, power, process limits and availability of an industrial plant can allow conclusions about production and business operations. A register therefore needs tiered access rights. The Norwegian pilot system has its own models for registration and permissions.

  • Flexibility is not static. It depends on weather, state of charge, production schedule, user behaviour, tariff, maintenance and contracts. Outdated master data can create false certainty. Updating, temporary suspension and deregistration therefore belong to the core processes of a register.

Double marketing and classification

If the same battery is scheduled simultaneously for local grid flexibility, balancing energy and self-consumption optimisation, its actual availability can easily be overestimated. A register can document such commitments or at least create the interfaces so that activations do not contradict each other. The unit remains physically the same, but its obligations must be compatible with one another.

A flexibility register thus describes neither a quantity of energy nor an instantaneous load. It describes how adjustable power becomes usable in an organised way at a specific location and under specific conditions. For flexibility to be genuinely used, units must be controllable, incentives must fit, data must be reliable and responsibilities must be clarified. The register does not accomplish these tasks alone. But it creates the shared information base without which flexible resources remain unused or are scheduled multiple times and in contradictory ways.

Sources

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Edited by eCMS on 12.11.2026 05:05

© 2026 Erik Schmidt. All rights reserved. Quotations with a link to the source are welcome.