Day-ahead electricity prices across Southeast Europe rose sharply on 28 May, but trading patterns showed the region no longer moved as a single synchronized block. Central European-linked hubs strengthened as imports tightened alongside a collapse in wind generation. Greece, Bulgaria and Albania stayed materially weaker as solar positioning improved and balancing pressure eased.
In Hungary, HUPX closed at €118.22/MWh, up €3.5/MWh day-on-day. Slovenia’s BSP increased to €116.29/MWh and Croatia’s CROPEX rose to €116.19/MWh. Serbia’s SEEPEX fell to €109.42/MWh, down €7.7/MWh, while Greece’s HENEX dropped to €89.64/MWh and Bulgaria’s IBEX declined to €94.67/MWh.
Italy remained the premium market at €131.30/MWh, supporting southbound spread economics for exporters and traders. The regional price divergence aligned with changes in generation and import availability during the day-ahead session.
Wind collapse and easing solar reshape system rebalancing
The main structural driver was a sharp fall in regional wind output. Forecast wind generation decreased by roughly 1,240 MW day-on-day to 1,953 MW, described as one of the steepest renewable declines of the week. Solar generation also eased by around 200 MW over the same period.
With renewables lower, thermal generation and imports adjusted to rebalance the system. Coal output increased by 358 MW, while gas-fired generation rose another 260 MW. The changes indicated renewed thermal marginality across the region on 28 May.
Despite weaker renewable output, total regional imports fell significantly. Net imports dropped to 526 MW, down more than 1,000 MW day-on-day. CORE imports from Austria and Slovakia declined by 1,460 MW.
Import tightening narrows spreads in Central Europe
The reduction in available imports supported stronger moves in Central European-linked hubs than in southeastern markets. Hungary’s spread versus Germany narrowed to -€4.10/MWh from a deeper discount the previous day. The compression reflected reduced cheap German renewable overflow into Hungary and across the broader SEE region.
Intraday trading showed continued midday price weakness tied to solar output, alongside sharper evening increases as solar faded and wind underperformed. HUPX peaked near €350/MWh during evening hour H21. Slovenia’s BSP briefly approached €394/MWh.
Batteries gain value from wider intraday spreads
The shift in intraday price shape is affecting battery storage economics across SEE. Markets increasingly monetized evening flexibility rather than relying only on baseload generation economics.
The widening gap between midday lows and evening peaks supported battery-backed solar portfolios, particularly in Bulgaria, Romania, Slovenia and Croatia where storage pipelines were accelerating rapidly. In Bulgaria, a newly commissioned Tenevo solar plant entered full operation alongside the first phase of a major battery system.
The 242 MW Tenevo project’s storage component is expected to reach 311 MW / 772.5 MWh once fully completed. In Romania, Hidroelectrica announced plans for 90 MW of floating solar on Lower Olt reservoirs paired with 200 MW / 800 MWh of battery storage.
Serbia expands “active buyer” framework for transmission-connected solar
Serbia’s market structure is also changing beyond conventional utility demand through new participation rules for industrial projects connected directly to the transmission system. EMS received the first applications under the new “active buyer” framework from HBIS Serbia and Linglong.
HBIS Serbia plans a 63 MW solar plant at Smederevo, while Linglong targets 39.9 MW in Zrenjanin under the same framework . The approach links industrial buyers with roles as consumers, producers, storage operators and potential electricity traders.
Gas stability, carbon support and hydrology remain key reference points
Austrian CEGH front-month gas traded near €47.48/MWh on 28 May, while EUA carbon allowances stayed elevated around €78.72/tCO₂ . Carbon pricing continued supporting gas-over-coal economics even as coal temporarily re-entered dispatch due to weaker renewable output.
Danube flows near 6,636 m³/s continued supporting regional hydro generation, although hydro output remained broadly flat day-on-day . Commercial flow patterns also showed Greece acting as a major regional balancing sink while Hungary maintained its position as the dominant Central European transit node into SEE markets.
During higher-priced evening periods, Serbia remained structurally import-linked to Hungary and Bosnia even as SEEPEX prices softened overall relative to neighboring hubs . Across SEE, volatility patterns increasingly reflected the interaction between renewables output and market flexibility rather than short-lived noise around renewable growth.
