The SEE electricity complex opened the week with a sharp rebound in spot prices across nearly all major regional exchanges, reversing the softer weekend structure and reintroducing tighter thermal-driven pricing conditions across Central and Southeast Europe. HUPX day-ahead prices surged to €138.68/MWh, while Romania’s OPCOM reached €139.51/MWh and Bulgaria’s IBEX climbed to €136.34/MWh, with most markets posting daily gains above €35–42/MWh. Greece remained structurally decoupled on the downside at €97.12/MWh, supported by stronger solar availability and lower regional tightness.
The latest regional move was driven by a combination of falling wind generation, lower hydro contribution, nuclear maintenance pressure and sharply rising evening peak pricing structures. Regional consumption increased to 28.1 GW, while total SEE generation fell to 21.7 GW, forcing the region into a net import position of roughly 2.16 GW. Hydro generation declined by 615 MW day-on-day, while wind production collapsed by 725 MW, one of the most important drivers behind the sudden tightening in balancing conditions.
The generation mix shows how structurally fragile the SEE market remains during renewable volatility periods. Hydro represented only 22% of the system mix, while wind contributed just 3%, forcing coal and gas-fired generation back into the marginal pricing stack. Coal generation rose by 156 MW, while gas-fired output remained elevated at 3.49 GW. Solar generation improved by 331 MW, but daytime solar strength was insufficient to offset the sharp evening scarcity premium visible across all regional curves.
Hourly curves confirmed the return of classic thermal stress pricing. HUPX evening hours again traded near or above €200/MWh, with the daily maximum reaching €200.9/MWh. Romania’s OPCOM peaked even higher at €212.2/MWh, while Bulgaria recorded maximum hourly prices near €177.6/MWh. Across the region, minimum prices remained barely above zero during midday solar hours, illustrating the increasingly violent intraday spread structure emerging from renewable penetration without sufficient storage depth.
The import structure also revealed renewed north-to-south dependence. Core imports from Austria and Slovakia into the Hungarian and SEE region remained extremely high at roughly 1.9 GW, while Italy continued to absorb regional export capacity. Greece remained a net importer at approximately 1.29 GW, while Hungary itself maintained heavy import reliance.
Several structural supply-side developments simultaneously reinforced bullish market sentiment.
Bulgaria’s Kozloduy nuclear plant began preparations for the scheduled maintenance outage of Unit 5, with shutdown activities commencing on 9 May and continuing toward mid-June. The outage removes one of the region’s most important baseload generation assets during a period already characterized by volatile renewable availability. The maintenance program includes reactor refueling using Westinghouse fuel assemblies, continuing Bulgaria’s strategic diversification away from Russian nuclear fuel supply.
Romania simultaneously extended the outage period for Cernavoda Unit 2 after a transformer-related technical fault forced automatic disconnection from the grid earlier this month. The replacement of transformer systems and additional controlled shutdown procedures further tightened regional nuclear availability. Compounding the situation, Unit 1 is also entering planned maintenance, increasing concerns around Romanian export capacity during the upcoming weeks.
Slovenia’s Krško nuclear plant also reported reduced effective export capability due to low Sava river levels and thermal discharge limitations. Although the reactor itself continues operating at full power, environmental cooling constraints reduced exported electricity to around 690 MW versus normal levels above 700 MW. The development highlights a broader structural risk emerging across Europe’s thermal and nuclear fleet as climate-linked hydrological constraints increasingly affect cooling systems and operational efficiency.
At the same time, weather forecasts suggest additional pressure may persist into midweek. Temperatures across SEE and Hungary are expected to decline after 11 May, especially in Slovenia, Croatia, Bulgaria and Romania, potentially sustaining stronger thermal demand while wind normalization remains uncertain.
Forward markets also reflected a firmer short-term structure. Hungarian Week-20 power forwards rose to €126/MWh, while Week-21 contracts reached €124.5/MWh. Carbon allowances strengthened further, with EUA Dec-26 contracts trading near €80/t, maintaining elevated pressure on coal and lignite generation economics throughout SEE.
Gas markets remained relatively stable despite broader geopolitical uncertainty. Austrian CEGH gas traded near €45.5/MWh, while Turkey continued negotiations with Algeria regarding expanded LNG imports potentially increasing from 4.4 bcm/year toward 6–6.5 bcm/year under a future long-term agreement. The talks also include potential LNG transit toward southeastern Europe via Bulgaria, a strategically important development for regional gas diversification and long-term balancing flexibility.
Renewable investment momentum across the region nevertheless remains extremely strong despite growing system balancing stress.
North Macedonia confirmed that solar capacity reached 962.6 MW, overtaking hydropower as the country’s second-largest installed generation technology. Solar generation rose by 27.7% year-on-year, while renewables now account for 46.4% of the national electricity mix. Importantly, the regulator also confirmed growing battery deployment activity, including new storage licenses linked to solar projects.
Montenegro officially launched trial operation at the 82 million euro Gvozd wind farm near Nikšić, expected to generate approximately 150 GWh annually and supply around 25,000 households. The project, financed by the EBRD and constructed by Nordex, represents one of the country’s most important renewable infrastructure investments and reinforces the broader acceleration of state-backed renewable deployment across the Western Balkans.
However, the current daily market structure increasingly demonstrates that renewable expansion alone is no longer sufficient to stabilize SEE electricity markets. The widening spread between midday and evening pricing, persistent import dependency, tightening nuclear availability and volatile hydro performance are accelerating the strategic importance of utility-scale battery storage, flexible gas generation, cross-border interconnection upgrades and balancing market modernization.
Without significant new flexibility infrastructure, the SEE market risks entering a structurally more volatile phase where high renewable penetration coexists with increasingly aggressive intraday pricing spikes, especially during periods of weak wind output and constrained hydro availability.