European Union regulators are preparing a framework to measure power-system flexibility needs, which could support commercial markets where industrial consumers, aggregators and distributed energy operators earn revenue by adjusting electricity use. The European Union Agency for the Cooperation of Energy Regulators (ACER) announced on October 21 that it would publish a preliminary version of EU-Flex, an open-source electricity-market model for assessing flexibility requirements across European power systems. A consultation is scheduled from November 5 to December 17, 2026, ahead of ACER’s first EU-wide flexibility-needs assessment, planned for July 2027.
EU-Flex is a methodological initiative, not a trading platform: it will neither authorise investments nor guarantee payments to providers. Its purpose is to offer a more transparent basis for determining which systems need additional flexibility, how much they need and where current resources are insufficient. For Southeast Europe, this could help make flexibility a measurable, contractable and potentially financeable service, rather than solely an operational requirement.
Demand response can become a market service
Electricity markets have traditionally valued industrial consumers for the electricity they buy and the reliability of their demand. The emerging model adds value to a consumer’s capacity to adjust consumption in response to a verified request. A factory able to cut demand for a predetermined period may offer that reduction as a service, while refrigeration facilities, heating systems, water pumping stations and EV charging operators may shift some operations without materially disrupting their core activities.
Such a facility could become a potential supplier of flexibility instead of acting only as a passive electricity customer. Demand reduction is not generation, but it can sometimes provide a balancing response equivalent to increasing production. Whether participation is commercially worthwhile depends on whether payments exceed the costs of operational disruption, equipment, administration and contractual liabilities.
Aggregators are central to this model because they combine multiple consumers’ flexibility into a portfolio large enough to meet minimum participation requirements. Aggregation can also offer a more dependable service than individual small facilities. The business requires digital controls, metering, consumption baselines, dispatch instructions and settlement arrangements.
Romania has activated aggregated demand for balancing
Romania provides an example of demand response moving from regulation into 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 relied on consumers reducing consumption, rather than on a generating plant or electricity-storage installation. Romanian regulations set a 1 MW minimum participation threshold for relevant balancing services, allowing smaller consumers to participate collectively through aggregation. The activation showed that a group of consumption points could meet technical qualification requirements and respond to actual system-dispatch instructions.
Separately, Romania’s regulator ANRE approved a consumption-flexibility mechanism in August, under which eligible consumers, suppliers and aggregators can offer voluntary demand reductions. Transelectrica assesses the required flexibility, participants submit price and quantity offers, and performance is verified by comparing consumption measurements with established baselines.
Together, the developments show a market structure emerging in which demand can play a more active role in system operation, but they do not establish its eventual size, annual turnover or sustainable profitability. Those outcomes depend on activation frequency, procurement volumes, competing resources and remuneration rules.
EU-Flex provides a common basis for assessing requirements
The initiative follows ACER’s approval, in July 2025, of a methodology for national electricity flexibility-needs assessments. Under the EU electricity-market framework, Member States had to prepare national assessments by July 2026 and are expected to establish 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, where national electricity systems have different technical and commercial requirements. A country may need resources to manage rapid changes in national demand, while a particular distribution area may need local demand reductions to prevent infrastructure overloads. These needs 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 procure the service, whether a provider can qualify and what revenues may reasonably be expected. EU-Flex could make the underlying assessment more transparent and allow investors and regulators to test assumptions against an open methodology.
Market readiness varies across Southeast Europe
Regional markets are progressing at different rates. Romania has an operating example of aggregated industrial demand participating in balancing services, while Croatia introduced an upgraded balancing platform in September 2026. The Croatian platform changed how reserve capacity and balancing energy are offered and created conditions for more flexible participation.
Bulgaria continues to face barriers linked 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.
Serbia has incorporated aggregation and independent aggregator concepts into its energy legislation, including provisions allowing 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 to provide services that may generate additional revenue.
Legislation alone does not amount to a fully operational market: effective 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.
Portfolio financing depends on performance and settlement
For investors and lenders, aggregation presents a different proposition from conventional electricity generation. An aggregator may own little physical energy infrastructure, with investment instead directed towards software, automation equipment, metering integration, customer acquisition and operational systems. Revenue may come from reserve availability, actual dispatch, customer services or contractual participation in other authorised flexibility mechanisms.
The resulting business is more like a technology-enabled energy-services company than a conventional power-plant operator, but underwriting presents challenges. Portfolio revenue depends on customer retention, verified response performance, regulatory access and continuity of market procurement. Profitability also requires clearly defined settlement arrangements among the aggregator, participating consumers, electricity suppliers and balance-responsible parties.
If a factory cannot reduce demand during a contracted activation, the aggregator may face penalties or replacement costs. Revenue forecasts therefore need to reflect the reliability of underlying industrial processes, not just their theoretical flexibility. A diversified portfolio could reduce exposure to individual customers, but it cannot remove systematic risks that affect several customers at the same time.
Measurement underpins participation and payment
Reliable evidence of delivered flexibility is a key commercial requirement. Metering systems, secure communications, operational records and independently reviewable consumption baselines determine whether a claimed reduction can be recognised as a market service. Smart meters and industrial energy-management systems may therefore support direct revenue generation as well as 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 more immediate commercial signal for Southeast Europe is Romania’s first operational demand-response activation, while ACER’s model sets out the longer-term regulatory framework. The two developments link measurable industrial and distributed electricity flexibility with the prospect of providing a reliable market service before traditional electricity companies establish those customer relationships.