The energy transition in Southeast Europe is increasingly influenced by the debate surrounding battery energy storage systems (BESS). As countries like Serbia, Greece, Romania, and Bulgaria expand their renewable energy capacities, the question arises: should these storage projects operate as fully merchant assets subject to market fluctuations or rely on regulated support mechanisms? This question is critical as it will define the region’s energy landscape by 2026.
Battery storage is no longer a peripheral component but has emerged as a central element of power systems across the Balkans. The region is witnessing the development of gigawatt-scale storage projects, driven by rising renewable penetration and volatile electricity markets. The chosen financing structure will dictate which projects are realized and which investors dominate the market, ultimately influencing how quickly Southeast Europe can establish a robust flexibility economy.
The case for merchant BESS models is becoming more compelling as market volatility increases. In Greece and Bulgaria, for instance, solar energy deployment has led to significant price drops during peak sunlight hours. Meanwhile, wind power generation in Serbia and Romania creates rapid balancing needs. Cross-border congestion adds another layer of complexity during periods of synchronized renewable output, widening the gap between low-price and high-price hours—conditions under which batteries can thrive.
Merchant batteries capitalize on these dynamics by absorbing inexpensive electricity during oversupply and discharging it during peak demand or shortages. Their revenue streams are derived from arbitrage opportunities, ancillary services, balancing participation, and congestion management rather than fixed tariffs or capacity payments. Theoretically, a sufficiently volatile market could sustain these systems without extensive regulatory backing.
This perspective is gaining traction among commodity traders and infrastructure funds who believe that increasing volatility will enhance the value of flexibility resources. They advocate for batteries to be treated as active trading entities rather than regulated utility assets. Serbia stands out as a pivotal testing ground for this approach, with agreements linked to approximately 4.54 GWh of planned storage indicating preparations for heightened market volatility.
However, while aggressive investors find potential in merchant models—particularly near congestion zones—many lenders remain wary. Traditional project finance tends to favor predictable revenue streams associated with established technologies like wind and solar that have historically benefited from feed-in tariffs or long-term power purchase agreements (PPAs). In contrast, merchant storage relies on uncertain future spreads and fluctuating market conditions, which raises concerns about financing viability.
This tension highlights the role of regulated-storage models in the ongoing debate. Under such frameworks, storage facilities receive stable revenue support through capacity payments or ancillary-service contracts designed to ensure system stability and resilience—benefits that may not be adequately compensated through purely merchant operations alone. Advocates argue that without clearer long-term revenue assurances, Southeast Europe risks underinvesting in storage solutions at a time when renewable volatility is expected to rise sharply.
Currently, the region’s balancing architecture remains in its infancy. Issues like uneven intraday liquidity and varying ancillary-service frameworks across countries complicate efforts to monetize battery capabilities effectively. As these challenges persist, pure merchant exposure may appear too risky for large-scale financing initiatives.
The philosophical implications of this debate are significant: should batteries function primarily as infrastructure supporting grid stability or as market-driven assets capitalizing on price volatility? Western Europe offers varied examples; regions like the UK have seen aggressive deployment of merchant batteries driven by intraday pricing dynamics while others rely more heavily on regulatory support structures.
Southeast Europe now faces similar crossroads but within a context marked by greater fragility in its markets. The response may vary by country; Greece’s solar-heavy profile supports merchant economics due to existing price spreads while Serbia might initially require hybrid frameworks until its balancing markets mature. Romania’s diverse energy mix could facilitate a combination of merchant optimization along with ancillary-service contracts.
The strategic consequences are profound: an overreliance on regulated support could slow down deployment and lead to utility-centric models while a rapid shift toward fully merchant setups might keep financing costs elevated and deployment inconsistent. A hybrid approach combining elements from both models could mitigate these risks while still allowing investors to benefit from potential volatility growth.
Transmission infrastructure plays an equally critical role in determining where storage assets will be most effective. Strategic locations near congestion nodes or interconnectors can yield significantly higher revenues compared to less optimally situated facilities due to improved access to regional balancing spreads.
In addition to transmission considerations, hydropower resources from countries like Albania and Montenegro create further opportunities for synergy with battery systems. Together they can form layered flexibility systems where hydropower manages longer-duration needs while batteries capture short-term fluctuations—a collaborative approach that may lessen reliance on regulatory support in some markets.
The Energy Community’s recent data reveals how structural pressures are reshaping regional electricity economics; commercial exchanges between EU nations and the Western Balkans have notably decreased amid substantial price disparities—an indicator that carbon exposure alongside congestion issues increasingly influences market behavior.
This evolving landscape underscores the necessity for clarity around how storage revenues will be monetized over time; uncertainty could deter investment when flexibility infrastructure is critically needed most. Nevertheless, it is clear that battery systems are transitioning from niche components into essential market infrastructure that will dictate whether renewable-heavy electricity grids remain stable and commercially viable moving forward.
The outcome of the ongoing financing debate between merchant versus regulated storage models will significantly influence not only battery deployment but also shape Southeast Europe’s entire electricity market trajectory over the coming decade.
