As the energy landscape in South-East Europe evolves, battery energy storage systems (BESS) are increasingly recognized as essential components of the grid. Positioned strategically between generation and transmission, BESS is transforming price dynamics and project economics across the region. With a projected deployment of 3–5 GW by 2030, including over 1 GW targeted in Greece through upcoming tenders, this shift marks a move from experimental projects to critical infrastructure.
The economic rationale for integrating storage into the energy mix is closely tied to the regional price structures. Notably, markets such as Greece (HEnEx), Romania (OPCOM), Bulgaria (IBEX), and Hungary (HUPX) have seen significant widening of intraday price spreads. In Greece, for instance, spreads driven by LNG pricing and solar energy saturation can reach €60–100/MWh, with peak days exceeding €120/MWh. Although spreads in Bulgaria and Romania are generally narrower—ranging from €30–70/MWh—they remain substantial during periods of high renewable generation or limited interconnections.
The financial viability of battery systems is defined by these price differentials. Current configurations for utility-scale assets typically range from 50–100 MW capacity with 2–4 hours duration, translating to storage volumes between 100–400 MWh. The capital expenditure (CAPEX) for these systems varies widely, with costs estimated at €400–600/kWh, leading to total project costs between €50 million for a 100 MWh system and up to €280 million for larger installations.
A primary revenue source for these storage systems is energy arbitrage, which involves purchasing electricity during low-price periods and selling it during peak demand. For example, a 200 MWh system operating in Greece can cycle approximately 250–300 times annually, capturing price spreads of around €50–80/MWh, resulting in gross revenues between €15–30 million per year. Systems in Bulgaria and Romania also contribute significantly, generating annual revenues between €10–20 million.
In addition to arbitrage, ancillary services are becoming an increasingly important revenue stream. Regulatory advancements are facilitating access to services like frequency containment reserve (FCR) and automatic frequency restoration reserve (aFRR). In Romania and Greece, these ancillary services can yield revenues of about €20–40/MW/year, adding an additional €1–4 million annually for mid-sized systems, thus enhancing overall revenue stability.
The combination of these revenue streams allows battery projects across South-East Europe to target equity internal rates of return (IRRs) ranging from 12–16%, with potential increases up to 20% in volatile markets like Greece. Debt financing options are also becoming more accessible, with leverage ratios between 50–65%, reflecting evolving revenue models that differ from traditional generation assets.
The integration of BESS with renewable generation further enhances financial returns. Hybrid projects that combine solar or wind facilities with co-located batteries are gaining traction in Serbia, Bulgaria, and Greece. For instance, pairing a 100 MW solar plant with a 200 MWh battery can elevate realized prices by approximately €8–20/MWh, which translates into additional annual revenues ranging from €10–25 million.
The Serbian market is witnessing early-stage hybrid projects designed around this model, particularly where curtailment risks exceed 10-15%. Developers are collaborating with trading firms like GEN-I, MET Group, and EFT, focusing on asset optimization strategies that balance merchant operations with partial power purchase agreement (PPA) coverage.
The Greek market stands out as the most developed storage sector within the region. Government initiatives have catalyzed deployment near high-volatility areas such as Thessaly and Central Greece. The interaction between storage capabilities and the country’s existing solar fleet—estimated at around 7-8 GW—is already influencing intraday pricing patterns.
This trend is mirrored in Romania where renewable growth coincides with grid constraints particularly evident in regions like Dobrogea. Storage solutions are being developed alongside wind and solar projects supported by both private investment and institutions like the European Bank for Reconstruction and Development (EBRD). Bulgaria’s pipeline may be smaller but shows promise due to its proximity to Greek pricing dynamics.
The role of energy traders is expanding significantly within this framework. Companies such as Axpo, MET Group, and PPC Trading—in addition to providing market access—are leveraging advanced algorithms to optimize battery revenue streams based on real-time data analysis. This optimization is crucial given that storage value relies on accurate timing relative to market fluctuations.
BESS is also reshaping transmission dynamics by alleviating pressure on interconnections during peak renewable output while supplying power during demand peaks. This capability could influence congestion pricing strategies moving forward.
However, increased storage capacity may lead to heightened competition for arbitrage opportunities that could compress price spreads.
The regulatory environment remains pivotal; clear frameworks governing market participation and ancillary service access are vital for sustaining growth in this sector. While Greece and Romania have made strides in establishing supportive regulations, other countries like Serbia and North Macedonia continue developing frameworks that recognize storage’s value more comprehensively.
The rise of BESS signifies a transformative shift within South-East Europe’s energy infrastructure landscape. As this new asset class gains prominence—distinguished from traditional generation by its focus on flexibility rather than production—the strategic placement of storage assets will be crucial for maximizing returns based on regional volatility patterns.
This ongoing evolution underscores the necessity for sophisticated operational strategies amid a dynamic grid environment where BESS will play an increasingly central role in shaping how electricity is generated, transmitted, and monetized across South-East Europe.
