Greece is testing a new electricity-market model in which transmission and distribution system operators can procure flexibility from the same pool of consumers and distributed energy resources. The approach could create an additional revenue stream for factories, commercial buildings and other electricity users capable of adjusting their consumption when needed.
The model is being demonstrated through the OPENTUNITY programme, under which transmission operator IPTO and distribution operator HEDNO have tested coordinated flexibility procurement through the NODES marketplace under real operating conditions.
The September results represent a step beyond conventional demand response. Rather than flexibility being offered to a single electricity-market participant, resources connected to the distribution network could provide value simultaneously to both the national transmission system and local distribution networks.
This raises an increasingly important commercial question: who has priority over the same flexible megawatt?
A factory capable of reducing its electricity consumption by 2 MW could support IPTO in balancing the wider Greek power system. At the same time, if that factory is located behind a distribution substation facing congestion, the same 2 MW could be particularly valuable to HEDNO.
Without proper coordination, separate requests from the two operators could conflict or simply move a network constraint from one level of the system to another. OPENTUNITY is testing mechanisms designed to avoid such outcomes.
Under the Greek pilot, both operators can access flexibility connected at distribution level, while the NODES platform coordinates procurement. A dedicated mechanism involving HEDNO, IPTO and NODES assesses the impact of potential activations on both networks before flexibility is dispatched.
The pilot is emerging as an example of a common flexibility market, in which transmission balancing needs and distribution-level congestion are addressed through a coordinated framework rather than through separate and potentially competing procurement processes.
The implications extend beyond grid management. Traditionally, industrial electricity consumers have viewed power mainly as an operating cost. In a functioning flexibility market, however, their ability to increase or reduce consumption at a particular time and location can become a separately tradable service.
Location is critical. Two factories with the same technical ability to reduce demand may have very different economic value if one is connected behind a heavily loaded substation while the other operates in an unconstrained part of the network. Flexibility therefore begins to acquire a locational value, potentially creating new opportunities for aggregators that build portfolios based not only on total flexible capacity but also on where those assets are connected.
Industrial refrigeration, water heating, HVAC systems, pumps, distributed generation, EV charging and other controllable assets could be aggregated and offered as flexibility products. The Greek pilot already includes portfolios of residential loads and distributed energy resources, showing how smaller assets can be combined to provide a commercially useful flexibility service.
For HEDNO, the potential benefit is clear. If a distribution constraint occurs only during a limited number of hours each year, paying customers to temporarily adjust their consumption could in some cases be more economical than immediately investing in new transformers, cables or other network infrastructure.
Flexibility could therefore become an alternative to part of traditional grid CAPEX, particularly as electrification, distributed solar generation, EV charging and new large electricity loads create increasingly uneven pressure across distribution networks.
The main challenge is ensuring that the same flexible resource is not effectively sold twice. An aggregator cannot commit a factory’s 2-MW reduction to IPTO while simultaneously guaranteeing the same capacity to HEDNO if both operators require it at the same time.
A functioning commercial market will therefore need clear rules covering availability, dispatch priority, baseline measurement, activation, verification and settlement. These coordination arrangements could ultimately prove just as important as the technology supporting the market.
The model also points to a broader evolution in the role of distribution system operators. DSOs have traditionally focused on planning, maintaining and reinforcing their networks. A local flexibility market could turn them into buyers of short-duration electricity services, allowing them to address some network constraints by procuring temporary changes in customer behaviour rather than relying exclusively on physical infrastructure investment.
This creates space for aggregators, energy-service companies and software providers to operate alongside traditional grid equipment suppliers. It could also give large electricity consumers several commercial relationships at the same time: a supplier providing electricity, an aggregator optimising their consumption, IPTO valuing their flexibility for system balancing and HEDNO valuing the same capability for a local network constraint.
Managing those overlapping relationships will be one of the next challenges as flexibility markets develop.
Greece’s pilot remains a demonstration rather than a mature nationwide flexibility market. However, the September results indicate that the technical architecture for coordinated TSO-DSO procurement can operate under real system conditions.
The wider market opportunity is consequently becoming clearer. As distributed energy resources continue to expand, electricity markets may no longer focus only on how many flexible megawatts are available. Increasingly, they will need to determine where those megawatts are located, who needs them and which grid operator can derive the greatest value from them at a given moment.
