UK storage developer Alcemi has bought a 2.3GWh portfolio of battery projects in Romania, and Slovakia has just switched on its largest BESS to date – two events that together mark Central and Eastern Europe’s transition from a storage pilot region into a mainstream deployment market. For anyone planning generation, grid, or storage assets in Europe, the significance is concrete: capital that previously concentrated in the UK, Germany, and Iberia is now rotating east, chasing wider balancing spreads, capacity market revenue, and a renewables buildout that is outrunning the grid’s ability to absorb it.
Why Romania and Slovakia are suddenly storage hotspots
Romania’s renewable buildout has accelerated sharply over the past two years, with solar capacity additions running on the order of several gigawatts annually – a pace driven by contract-for-difference auctions, EU recovery funding, and corporate PPAs. Much of that generation is sited in the southern and western parts of the country, where the transmission network was never designed for large, variable infeed. The predictable consequence is emerging: curtailment risk, negative price intervals, and growing congestion on the grid. Storage is the obvious relief valve, and the country’s grid operator has publicly signaled that flexibility is a priority investment area.
Romania also has a functioning capacity market that pays for availability, which gives storage projects a revenue floor that pure merchant markets in some Western European countries lack. That combination – high variable generation, weak grid, and a capacity mechanism – is precisely the recipe that produced the UK’s and Germany’s storage booms a few years earlier. Alcemi, a developer behind some of the UK’s largest battery projects, is essentially importing that playbook into a market where the same dynamics are now maturing.
Slovakia presents a different profile, and that is worth understanding. Its renewables penetration is lower than Romania’s, but it has a heavy industrial load and sits as a transit corridor between Poland, Hungary, Austria, and the Czech Republic. Cross-border flows create balancing needs that are structural rather than driven by overgeneration. The country’s largest BESS coming online gives the TSO a new tool for frequency regulation and congestion management, but it is also a proof point: it demonstrates that large-scale storage is commercially viable in a market with comparatively modest renewables penetration. That matters because Slovakia’s grid needs flexibility for reasons that have little to do with solar oversupply.
The EU-level backdrop reinforces both stories. The bloc’s electricity market design reform, agreed in 2024, explicitly requires member states to assess flexibility needs and supports capacity mechanisms that allow storage to compete. The REPowerEU plan and national recovery and resilience facilities have earmarked substantial funds for grid and storage investment across CEE. Romania’s recovery plan in particular includes dedicated storage support. The regulatory scaffolding that Western Europe built over a decade is now being erected in the east in compressed time.
What Alcemi’s eastward move says about European storage economics
Alcemi’s entry into Romania is best understood as a capital rotation story, not a one-off project acquisition. The UK storage market, where Alcemi built its reputation, has matured to the point of revenue compression: ancillary services prices have fallen as more capacity has come online, and the merchant-plus-capacity revenue stack that early projects enjoyed is thinner than it was three or four years ago. The same dynamic is visible in Germany, where the storage pipeline is enormous and competition for balancing revenue is intense. Developers with proven execution capability are looking for markets where spreads per MWh are wider and the competitive field is thinner. CEE fits that description.
The scale of the Romanian acquisition is worth putting in context. If the 2.3GWh portfolio is built at typical utility-scale durations of two hours, it represents roughly 1.1 to 1.2GW of power capacity – a very large addition relative to Romania’s existing installed storage base, which remains small, on the order of a few hundred megawatts to date. To put that in broader perspective, Europe as a whole is now deploying on the order of 10 to 15GW of storage annually, with the UK, Germany, and Italy dominating. A single 2.3GWh CEE portfolio does not change the continental picture, but it does signal that the region’s share of that deployment is about to grow significantly from a low base.
The economics that make this work are specific to CEE market structure. Balancing markets in Romania and Slovakia are shallower and less efficient than in Western Europe, which means price volatility – and therefore the spread between charging and discharging prices – can be several times higher on a per-MWh basis than what a UK or German project captures today. Early movers in thin markets capture outsized spreads before new entry compresses them. That is the classic first-mover arbitrage, and it is exactly why a developer with Alcemi’s track record would enter now rather than wait for the market to mature.
There is also a validation effect at work. When a credible Western developer with a large UK portfolio commits capital to a CEE market, it de-risks the region in the eyes of lenders, EPC contractors, and equity investors. That tends to accelerate follow-on entry by other Western players, which in turn compresses the spreads that made the market attractive in the first place. The window for outsized returns in Romanian storage is likely open for a limited number of years – perhaps two to four – before the market normalizes. That timeline is consistent with how the UK market evolved after its initial storage wave.
One more dynamic deserves attention: Romania’s position as a periodic net electricity exporter and importer, and Slovakia’s role as a transit hub, create cross-border arbitrage opportunities that storage can capture. A battery in Romania can charge when regional prices are low – often during solar peaks in neighboring countries – and discharge when prices spike, whether the spike originates domestically or from a cross-border flow. This regional price coupling means the revenue stack for CEE storage is not purely domestic; it is a function of the entire Central European market’s dynamics. That adds complexity to revenue modeling but also diversity, which investors generally price favorably.
Who the CEE storage buildout changes things for
- Utility and grid planners: Romania’s and Slovakia’s TSOs and DNOs should update their flexibility and network development assumptions now – a 2.3GWh influx plus follow-on projects changes congestion patterns, reserve requirements, and the value case for transmission upgrades. Storage is no longer a pilot; it is a planning input.
- Storage developers: Alcemi’s entry is a template for the CEE playbook: secure grid connections early, stack capacity market and balancing revenue, and partner with local EPC and O&M providers who understand the regulatory environment. Western developers considering the region should move on connection queue positions before they tighten.
- Policy analysts and regulators: The pace of deployment now hinges on whether Romanian capacity market rules let storage compete fairly with generation, and on how quickly EU recovery funds are disbursed. Regulatory friction here will be the binding constraint, not capital availability.
- Investors: CEE storage offers materially higher spreads than saturated Western markets, but with higher regulatory and counterparty risk. The risk premium is narrowing as credible developers enter – the window for underwriting projects at wide margins is finite, likely a few years at most.
Milestones to track in the CEE storage market
- Alcemi’s commissioning timeline: Whether the 2.3GWh Romanian portfolio hits its stated development targets in the 2026-2027 window will be the clearest signal of whether CEE execution risk matches Western European norms.
- Romania’s next capacity market auctions: Whether storage assets clear these auctions, and at what price, will determine whether the capacity mechanism becomes a durable revenue pillar or a one-off support scheme.
- Slovak follow-on projects: Whether the newly operational BESS triggers a pipeline of similar-scale developments in Slovakia, or remains an isolated flagship, will indicate whether that market reaches critical mass or stays niche.
- Balancing price trends in Romania: Watch the spread between peak and off-peak balancing prices over the next 12-18 months – compression there will signal that new entry is already eroding the first-mover advantage.
- EU fund disbursement rates: The pace at which Romanian and Slovak recovery plan storage allocations actually reach projects will separate markets that scale from those that stall.
Bottom line
The CEE storage market has crossed from pilot to pipeline phase, and Alcemi’s 2.3GWh Romanian acquisition is the clearest evidence yet that Western capital and execution capability are now treating the region as a core market rather than an option. The next two years will determine whether the region’s balancing spreads hold up as new capacity arrives – and whether the capacity market and EU funding turn these projects into a durable asset class or a front-loaded boom.
Read the full report at Energy Storage News.
Note: facts and figures attributed above to Energy Storage News reflect that outlet's original reporting. Broader context, cross-sector connections, and forward-looking scenarios reflect independent analysis by our editorial team.
About this article: Drafted by Energy Ai with AI-assisted research and writing based on public reporting, then reviewed under our editorial process before publication.
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