The final month of 2025 finds the electricity markets of South-East Europe entering winter with a stability few would have predicted even two years ago. The whip-saw volatility of the post-Ukraine crisis era has eased, gas is trading at multi-year lows, cross-border interconnections are stronger, and the Single Day-Ahead Coupling (SDAC) has compressed price spreads across borders that once behaved like separate energy continents. Yet beneath the veneer of calm, December’s early price movements reveal a more complex mosaic — one shaped by geography, hydrology, generation structure and the growing gravitational pull of the Central European power market.
Hungary’s HUPX, Romania’s OPCOM, Serbia’s SEEPEX and Bulgaria’s IBEX form the region’s pricing backbone, and as December begins they are moving within a remarkably tight band. November closed with baseload averages around 119–125 euros per megawatt-hour across the three largest exchanges, while Bulgaria carried its typical mild premium. The engine behind this convergence lies upstream in the fuel market: TTF gas futures slipped to an eighteen-month low at the turn of the month, clearing just under 30 euros per megawatt-hour for January delivery. Such pricing effectively caps the marginal cost of gas-fired generation, and with it the entire regional winter merit order.
Yet the start of December still produced moments of turbulence. Serbia’s SEEPEX experienced sharp daily swings, with prices surging above 150 and even 168 euros on the first two delivery days before collapsing below 100 euros on the sixth. Albania felt the echo of these oscillations immediately, despite enjoying unusually high reservoir levels in November after generous rainfall. Montenegro mirrored SEEPEX almost hour by hour, its small system absorbing regional price movements with little insulation from domestic generation. Even Bulgaria — historically prone to outsized volatility due to lignite availability, nuclear scheduling and export pressure — aligned smoothly with its neighbours at 125–135 euros, despite winter demand starting to build.
The region’s cohesion stands in contrast to the fragmentation of earlier years. Croatia’s HROTE-market prices now closely resemble Slovenia’s and Hungary’s, reflecting tighter integration with the Alps–Pannonian corridor rather than older Balkan patterns. Montenegro and Albania no longer set their own pricing rhythm: Montenegro moves with Serbia, while Albania’s hydro-driven exports and imports pulse along the same signal, amplifying it during tight days and softening it during hydro-rich ones. Even Greece, once considered a semi-isolated market, now trades within a regional framework shaped by interconnections to Bulgaria, North Macedonia and Italy. Greek prices in early December are not materially decoupled from Bulgarian or Hungarian levels, hovering around 125–145 euros with a volatility profile driven more by wind variability and gas dispatch than by the structural isolation that once defined the Greek electricity system.
Greece’s transformation is particularly telling. The country’s decarbonisation strategy has pushed lignite out of the merit order, increasing gas dependence but also making the market more sensitive to pan-European gas trends than to domestic coal availability. When TTF fell to 30 euros, Greek CCGTs quickly became competitive across the region, pushing Greek baseload into convergence with Bulgaria and northern markets. Wind contributed to day-to-day swings: strong Aegean winds in the first week of December depressed prices sharply, creating the occasional intraday differential with Bulgaria and North Macedonia. But the broader pattern shows unmistakable alignment. Greece no longer sits at the edge of the European system; it has become an integral part of the South-East European price basin.
Bulgaria continues to hold a strategic role within this landscape. IBEX prices traditionally run higher than HUPX or OPCOM due to structural lignite costs, seasonal nuclear output patterns and export transmission constraints. Yet December 2025 shows a market moving more smoothly than in previous winters. Exports into Greece and Romania remain healthy, but the absence of severe cold in early December has kept baseload around 125 euros — just high enough to reflect structural costs, but not high enough to distort regional flows. If winter remains normal, Bulgaria may become a stabiliser rather than a price amplifier for the region, especially as Greece’s gas-heavy system increasingly balances against Bulgarian exports during evening peaks.
This stabilisation across the major hubs forms the backdrop for the peripheral exchanges in Croatia, Montenegro and Albania. Croatia’s integration into the Central European price cluster is now near-complete. December prices follow the Hungarian–Slovenian signal with minimal deviation, reflecting a system that imports market discipline from its neighbours rather than relying on domestic generation. Montenegro, meanwhile, remains tied to Serbia’s thermal and hydro availability. When SEEPEX jumped above 160 euros on the second day of December, Montenegrin purchases cleared at the same levels almost instantly — a direct expression of the country’s structural dependence on regional supply. Yet as soon as weather softened and SEEPEX prices fell, Montenegro returned to the same low-volatility corridor that characterises its December trading so far.
Albania continues to be the outlier in structure but no longer in price formation. The country’s hydro dominance still produces volatility both within the day and across the month. But regional import prices now anchor Albania’s winter exposure more than ever. When neighbouring markets price in the 120–130 euro range, Albania’s effective wholesale cost cannot escape that gravitational field, regardless of hydrological conditions. Only during severe droughts — not yet visible this winter — can Albania deviate upwards significantly, and even then it does so by mirroring the peaks of its neighbours rather than setting a distinct trajectory.
Taken together, the December 2025 picture shows a region that has matured into a single loosely coupled electricity market. Differences remain, but they are increasingly marginal and driven by temporary conditions rather than structural disalignment. Thermal outages in Serbia, hydro shortages in Albania, wind swings in Greece or lignite constraints in Bulgaria still create short-lived price spikes. But the overall dispersion is now far narrower than the region has historically known, a testament to the power of SDAC coupling and the broader integration of South-East Europe into Europe’s energy architecture.
Forecasting the first quarter of 2026 within this framework is an exercise in bounding rather than predicting. The baseline scenario — mild weather, stable gas in the 25–35 euro range, no major generation shocks — points to monthly baseload averages in the 115–135 euro corridor for HUPX, OPCOM, SEEPEX, HROTE and Greece, with IBEX slightly above at 125–145 euros. Montenegro will remain tied to SEEPEX within a margin of a few euros, while Albania’s effective cost will align with the lower end of the regional band unless hydrology deteriorates. Croatia will shadow Hungary almost perfectly.
The second scenario, a cold-winter tightening, would push January and February into the 150–170 euro range for the major exchanges and would lead to particularly sharp spikes in Albania and Montenegro if hydro output weakens. Greece would feel the pressure earlier than others due to its reliance on gas, while Bulgaria might become the primary exporter during peak hours, setting higher marginal prices across its interconnections. The stress would not be catastrophic in the manner of 2022, but it would remind the region that convergence does not abolish vulnerability.
The third scenario, a mild-winter continuation of current trends, would bring the region one of its most stable first quarters in a decade. Prices could drift below 110 euros for extended stretches, especially if renewables output is favourable and cross-border congestion remains limited. In such a scenario, South-East Europe would operate as a single, synchronised market defined more by weather than by structural fragility.
The core message emerging from December 2025 is one of cautious optimism. The Balkan power system has moved closer to the European core, not only institutionally but behaviourally. Price formation is now driven by fundamentals rather than fear, by regional flows rather than national silos, and by integrated market mechanisms rather than improvised crisis coordination. As the region heads into Q1 2026, the winter price curve is no longer a barometer of instability but a measure of normalisation. The mosaic remains complex, but the pieces now fit together.
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