European regulators are preparing a framework to measure power-system flexibility, as commercial markets could allow industrial consumers, aggregators and distributed energy operators to earn revenue by changing when and how they use electricity. On October 21, the European Union Agency for the Cooperation of Energy Regulators (ACER) announced it would publish a preliminary version of EU-Flex, an open-source model for assessing flexibility requirements in European power systems. Consultation is scheduled to run from November 5 to December 17, 2026, ahead of ACER’s first EU-wide flexibility-needs assessment, planned for July 2027.
EU-Flex will assess needs, not create a trading platform
EU-Flex is a methodological initiative, rather than a commercial one. It will not establish an electricity trading platform, authorise investments or guarantee payments to flexibility providers. Its purpose is to provide a more transparent basis for determining which power systems need additional flexibility, how much they require and where existing resources are insufficient.
For Southeast European markets, this could help move flexibility from an operational necessity towards a service that is measurable, contractable and potentially financeable. Electricity markets have traditionally valued industrial consumers for the power they buy and the reliability of their demand. The emerging model adds potential economic value when consumers change their consumption in response to a verified request.
A factory able to cut electricity use for a predetermined period may offer that reduction as a service. Refrigeration facilities, heating systems, water pumping stations and EV charging operators may also be able to shift some operations without materially disrupting their main business. These facilities could become suppliers of flexibility rather than passive electricity customers.
Demand reduction is not generation, but it can provide an equivalent balancing response when the system can reduce consumption instead of increasing production. The commercial case depends on whether payments exceed the costs of operational disruption, additional equipment, administration and contractual liabilities. Aggregators can combine consumers’ flexibility into portfolios large enough to meet minimum participation requirements and offer a more dependable service than individual small facilities.
That business model relies on digital controls, metering systems, consumption baselines, dispatch instructions and settlement arrangements. Aggregation is central because it allows smaller consumers to participate collectively. The value of a portfolio therefore depends both on consumers’ ability to respond and on the systems used to measure and manage that response.
Romania has activated aggregated demand in balancing services
Romania provides an example of demand response moving from regulation into commercial operation. On September 1, 2026, transmission operator Transelectrica activated a balancing reserve group made up entirely of controllable electricity demand. Organised by Romanian aggregator Flexumers, the portfolio delivered a 3 MW demand reduction during a 30-minute activation on the manually activated frequency restoration reserve market.
The reserve did not rely on a generating plant or an electricity-storage installation; its resource was consumers’ ability to reduce consumption. Romanian regulations set a 1 MW minimum participation threshold for relevant balancing services, allowing smaller consumers to participate together through aggregation. The activation showed that a group of consumption points could meet technical qualification requirements and respond to actual system-dispatch instructions.
In August, Romania’s regulator, ANRE, separately approved a consumption-flexibility mechanism under which eligible consumers, suppliers and aggregators can offer voluntary demand reductions. Transelectrica assesses the flexibility required, participants submit price and quantity offers, and performance is verified by comparing measured consumption with established baselines. Together, the activation and the mechanism show an emerging structure for demand-side participation in system operation.
They do not establish the market’s eventual size, annual turnover or sustainable profitability. Those outcomes depend on activation frequency, procurement volumes, competing resources and remuneration rules. Romania’s example demonstrates an operational response, but does not determine the scale of future commercial activity.
ACER methodology aims to clarify flexibility requirements
EU-Flex follows ACER’s approval in July 2025 of a methodology for national electricity flexibility-needs assessments. Under the EU electricity-market framework, Member States were required to prepare national assessments by July 2026 and are expected to set indicative non-fossil flexibility objectives by January 2027. The methodology distinguishes system-wide flexibility needs from flexibility needed to manage network constraints.
The distinction matters in Southeast Europe because national power systems have different technical and commercial requirements. A country may need resources to manage rapid changes in national electricity demand, while a particular distribution area may need local demand reductions to prevent infrastructure overloads. These needs can call for different services, procurement arrangements and contract structures.
A national flexibility shortage does not, by itself, demonstrate demand for a particular privately developed asset. Investors need to establish whether the relevant system operator can purchase the service, whether a provider can qualify and what revenues could reasonably be expected. EU-Flex could make assessments more transparent and allow investors and regulators to test assumptions against an open methodology.
Market readiness varies across Southeast Europe
Regional market development is uneven. Romania has an operating example of aggregated industrial demand participating in balancing services. Croatia introduced an upgraded balancing platform in September 2026, changing how reserve capacity and balancing energy are offered and creating conditions for more flexible participation.
Bulgaria continues to face barriers related to limited demand-response participation and low smart-meter penetration. The European Commission’s 2026 country assessment identified the limited development of Bulgarian demand response as an obstacle to more flexible electricity-market operation. These conditions contrast with the operational activity reported in Romania.
Serbia has incorporated aggregation and independent aggregator concepts into its energy legislation, including provisions that allow eligible customers to contract with independent aggregators. In August 2026, its regulator also consulted on procedures for switching suppliers and aggregators. Serbian industrial consumers could use controllable production schedules, auxiliary processes and other flexible loads in services that may generate additional revenue.
Legislation alone does not make a market fully operational. Participation also requires technical qualification, data exchange, settlement rules and enforceable commercial arrangements. Montenegro and other Western Balkan markets could examine comparable structures as their electricity-market rules and digital infrastructure develop.
Aggregation offers investors a different financing model
For investors and lenders, flexibility aggregation presents a different opportunity from conventional electricity generation. An aggregator may own little physical energy infrastructure, with its principal investment instead directed to software, automation equipment, metering integration, customer acquisition and operational systems. The resulting business resembles a technology-enabled energy-services company more than a conventional power-plant operator.
Revenue may come from reserve availability, actual dispatch, customer services or contractual participation in other authorised flexibility mechanisms. Lenders nevertheless face underwriting challenges because portfolio income depends on customer retention, verified response performance, regulatory access and continued market procurement. The business also needs clearly defined settlement arrangements between aggregators, participating consumers, electricity suppliers and balance-responsible parties.
If a factory cannot reduce demand during a contracted activation, its aggregator may face penalties or replacement costs. Revenue forecasts therefore need to account for the reliability of industrial processes, not just their theoretical flexibility. A diversified portfolio could reduce exposure to individual customers, but would not eliminate systematic risks affecting several customers at once.
Measurement is essential to recognising flexibility
Reliable evidence of delivered flexibility is a decisive commercial requirement. Metering systems, secure communications, operational records and independently reviewable consumption baselines determine whether a claimed reduction can qualify as a recognised market service. Smart meters and industrial energy-management systems may therefore support revenue generation in addition to their traditional functions in billing and efficiency monitoring.
The November consultation gives regulators, system operators and market participants an opportunity to examine how future EU-wide flexibility needs will be modelled. The investment implications are expected to become clearer later, when assessed requirements are translated into procurement mechanisms, eligibility rules and revenues. Romania’s first operational demand-response activation provides an immediate commercial signal, while ACER’s model offers a longer-term regulatory framework for turning measurable industrial and distributed electricity flexibility into a reliable market service before traditional electricity companies establish those customer relationships.