How Battery Storage Is Redesigning Electricity Markets Across Europe

Battery storage is often discussed in terms of installed capacity, investment pipelines and revenue potential. But one of the most profound transformations is happening behind the scenes: the redesign of electricity market infrastructure itself.

At Balkan Battery Day 2026, Andreas Ntomaris, Director, Non-Coupled Markets Operation, Hellenic Energy Exchange (HEnEx) presented how Greece is adapting its electricity market to integrate battery storage into day-ahead and intraday trading. While focused on the Greek market, his presentation illustrated a much broader trend that is emerging across Europe.

As batteries become a central component of power systems, electricity markets must evolve alongside them.

Batteries No Longer Fit Traditional Market Models

Conventional electricity markets were designed around relatively simple roles.

Generators produced electricity.

Suppliers sold it.

Traders connected different markets.

Battery storage fundamentally changes that structure.

As Andreas Ntomaris explained, modern electricity systems increasingly include:

• standalone battery operators
• hybrid renewable and storage projects
• aggregators managing distributed assets
• flexible demand participants
• co-located renewable systems

Unlike conventional generators, batteries can simultaneously consume electricity, inject power into the grid and provide flexibility services depending on market conditions.

Supporting these multiple roles requires entirely new participation models, scheduling processes and operational rules.

Integrating batteries into electricity markets is therefore far more complex than simply allowing them to trade electricity.

Battery Trading Requires New Market Mechanisms

One of the presentation’s key insights was that battery trading operates under constraints that traditional generators do not face.

Every charging decision affects future discharge capability.

Every discharge limits future flexibility.

Battery operators therefore cannot submit independent charging and discharging bids without considering the interaction between the two.

To address this challenge, HEnEx introduced circular block orders, a trading mechanism that links charging and discharging transactions into a single coordinated strategy.

This prevents situations where a battery secures a discharge position without sufficient charging energy or charges its battery without later being able to sell that energy efficiently.

The concept illustrates a broader evolution taking place across European electricity markets.

Trading is becoming less about selling electricity and increasingly about managing flexibility under technical and operational constraints.

Market Design Must Support Multiple Asset Types

Another major focus of the presentation was the creation of dedicated participation models for different storage configurations.

HEnEx has introduced separate frameworks for:

• large standalone battery systems
• aggregated storage portfolios
• hybrid renewable and storage projects
• dispatchable and non-dispatchable portfolios
• aggregators managing mixed energy assets

Future electricity systems will rely on a diverse mix of technologies rather than a single dominant asset class.

Large batteries, rooftop solar, flexible demand and hybrid renewable projects will increasingly operate together within the same electricity markets.

Creating market structures that support this diversity without adding unnecessary complexity is becoming a key challenge for market operators.

Flexibility Is Becoming More Valuable Than Energy Alone

One of the most interesting observations from Greece’s testing phase concerned how battery operators actually use their assets.

Rather than fully charging or fully discharging their batteries, operators deliberately preserve part of their available capacity.

The reason is straightforward.

A fully discharged battery cannot respond to balancing events.

A fully charged battery has limited ability to capture future market opportunities.

Instead of maximising immediate energy trades, operators increasingly optimise around optionality.

Battery systems continuously evaluate whether it is more valuable to:

• trade energy
• preserve reserve capacity
• provide balancing services
• respond to grid events
• maintain flexibility for future market conditions

This represents a fundamental shift from the operating logic of conventional power plants.

Battery storage is evolving into a real-time flexibility management system.

Aggregators Will Play a Growing Role

The presentation also highlighted the increasing importance of aggregators.

As battery deployment expands, particularly across smaller distributed systems, aggregators can combine fragmented assets into portfolios capable of participating efficiently in electricity markets.

This role may become especially important across Southeast Europe, where distributed renewable generation is growing rapidly while grid infrastructure continues to evolve.

Aggregators can unlock flexibility from:

• small battery installations
• distributed solar-plus-storage systems
• commercial energy management systems
• flexible industrial demand

As renewable penetration increases, this aggregated flexibility will become increasingly valuable for maintaining system balance. 

Europe Is Only at the Beginning

Although momentum around battery storage continues to accelerate, Greece’s experience also demonstrates how early the market still is.

At the time of the presentation, only around 200 MW of battery capacity was participating in market testing.

National deployment targets point toward approximately 900 MW in the near future, while longer-term projections suggest several gigawatts of battery storage could be operating by 2030.

Meeting those ambitions will require continuous evolution of market rules, optimisation platforms and balancing mechanisms.

The Energy Transition Is Becoming a Market Design Challenge

The broader message from Andreas Ntomaris’ presentation extended well beyond Greece.

Battery storage is transforming not only the physical electricity system, but also the rules that govern how electricity markets function.

As renewable generation grows, competitiveness will increasingly depend on flexibility, optimisation and intelligent market participation rather than generation capacity alone.

Europe’s energy transition is therefore becoming as much a challenge of market design and operational intelligence as one of infrastructure investment.