Day-ahead electricity markets across SEE moved sharply higher on 28 May, but the region no longer traded as a single synchronized block. Central European-linked hubs surged on tightening imports and collapsing wind generation, while Greece, Bulgaria and Albania remained materially weaker under stronger solar positioning and softer balancing pressure.
Hungary’s HUPX closed at €118.22/MWh, up €3.5/MWh day-on-day, while Slovenia BSP jumped to €116.29/MWh and Croatia CROPEX to €116.19/MWh. Serbia SEEPEX diverged lower at €109.42/MWh, falling €7.7/MWh, while Greece HENEX dropped to €89.64/MWh and Bulgaria IBEX to €94.67/MWh. Italy remained the premium market at €131.30/MWh, preserving strong southbound spread economics for exporters and traders.
The most important structural driver was the collapse in regional wind production. Forecast wind output fell by roughly 1,240 MW day-on-day to 1,953 MW, one of the sharpest renewable declines of the week. At the same time, solar generation also eased by around 200 MW, forcing thermal generation and imports to rebalance the system. Coal output increased by 358 MW, while gas-fired generation rose another 260 MW, confirming renewed thermal marginality across the region.
Despite weaker renewable generation, total regional imports actually fell sharply. Net imports dropped to only 526 MW, down more than 1,000 MW day-on-day, while CORE imports from Austria and Slovakia collapsed by 1,460 MW.
That tightening of import availability explains why Central European-linked hubs strengthened more aggressively than southeastern markets. Hungary’s spread versus Germany moved to -€4.10/MWh, a major narrowing from the previous day’s deep discount. The compression reflected reduced cheap German renewable overflow into Hungary and the broader SEE region.
Intraday profiles showed the region still experienced deep solar-driven midday price collapses, but evening ramps became increasingly violent. HUPX peaked near €350/MWh during evening hour H21, while Slovenia BSP briefly approached €394/MWh, illustrating how quickly liquidity and flexibility disappear once solar fades and wind underperforms.
This continues to reshape battery storage economics across SEE. Markets are increasingly monetizing evening flexibility rather than baseload generation alone. The widening spread between midday lows and evening peaks remains structurally supportive for battery-backed solar portfolios, particularly in Bulgaria, Romania, Slovenia and Croatia where storage pipelines are accelerating rapidly.
Bulgaria remains the clearest example of this transition. The newly commissioned 242 MW Tenevo solar plant entered full operation alongside the first phase of a major battery system. Once fully completed, the project’s storage component is expected to reach 311 MW / 772.5 MWh, making it one of the region’s largest hybrid renewable assets.
Romania is moving in the same direction through hydro-solar-storage integration. Hidroelectrica announced plans for 90 MW of floating solar on Lower Olt reservoirs combined with 200 MW / 800 MWh of battery storage. The model increasingly reflects a regional shift toward hybridized assets capable of capturing volatility rather than depending purely on energy sales.
Serbia’s market structure is also evolving beyond conventional utility demand. EMS received the first applications under the new “active buyer” framework from HBIS Serbia and Linglong, which plan large self-generation solar projects connected directly to the transmission system. HBIS intends to build a 63 MW solar plant at Smederevo, while Linglong targets 39.9 MW in Zrenjanin.
This matters for SEE power markets because industrial buyers are beginning to act simultaneously as consumers, producers, storage operators and potential electricity traders. The traditional separation between industrial demand and generation portfolios is starting to disappear, particularly under CBAM-related pressure to secure lower-carbon electricity supply.
For banks and investors, daily volatility patterns increasingly matter as much as annual averages. The region is transitioning toward a market where flexibility value, balancing capability, SCADA visibility, storage integration and transmission positioning can materially influence project bankability and long-term merchant exposure.
Gas markets remained relatively stable despite ongoing geopolitical concerns. Austrian CEGH front-month gas traded near €47.48/MWh, while EUA carbon allowances stayed elevated around €78.72/tCO₂. Carbon pricing therefore continues supporting gas-over-coal economics in several markets even as coal temporarily re-entered dispatch because of weaker renewable output.
Hydrology remains another stabilizing factor. Danube flows near 6,636 m³/s continue supporting regional hydro generation, although hydro output itself remained broadly flat day-on-day.
Commercial flow patterns also continued showing Greece acting as a major regional balancing sink, while Hungary preserved its position as the dominant Central European transit node into SEE markets. Serbia remained structurally import-linked to Hungary and Bosnia during higher-priced evening periods, even as SEEPEX prices softened overall relative to neighboring hubs.
The broader market signal remains increasingly clear across SEE: volatility is no longer temporary noise around renewables growth. It is becoming the central economic feature of the regional electricity market itself.