During the first half of May 2026, gas-fired generation increased across the broader HU+SEE system while overall electricity demand fell. Gas output rose by approximately 362 MW, while total regional demand declined by roughly 1,018 MW. At the same time, nuclear generation dropped by 1,686 MW, coal output fell by 260 MW, and hydro generation weakened by another 357 MW. This shift coincided with intensifying renewable volatility and declining thermal reliability across the region.
May 2026 price spikes on OPCOM, HUPX and SEEPEX
The market response was reflected in higher day-ahead prices across multiple exchanges. Romania’s OPCOM rose to €115.88/MWh, Hungary’s HUPX reached €108.62/MWh, and Bulgaria’s IBEX climbed to €104.98/MWh. Croatia’s CROPEX averaged €105.77/MWh, while Serbia’s SEEPEX moved above €101/MWh. These levels were recorded despite weaker consumption and improving temperatures.
The price pattern indicated that marginal generation scarcity played a larger role in setting electricity costs than demand conditions alone. Gas was identified as the technology most capable of supplying the balancing function required during the period. In parallel, carbon prices eased to around €74.96/t, while fuel costs remained supportive of thermal marginal pricing. CEGH gas prices averaged approximately €46.64/MWh, with Greek gas prices near €45.22/MWh.
Nuclear outages and coal underperformance tighten supply margins
The supply mix changes were linked to outages and weaker performance in baseload assets. Nuclear generation experienced significant outages and maintenance interruptions, including Bulgaria’s Kozloduy Unit 5 entering maintenance and Romania’s Cernavoda Unit 2 remaining affected by extended technical issues. Coal plants also faced operational instability and worsening economics across parts of the Western Balkans.
RiTE Ugljevik spent months offline before returning to operation in early May, according to reported developments during the period. RiTE Gacko reported sharply deteriorating profitability, while Montenegro’s Pljevlja coal operations showed worsening financial performance . Across Bosnia and Herzegovina, Montenegro and Serbia, aging coal infrastructure was described as facing maintenance challenges, financing stress and environmental pressure.
Renewables expansion raises balancing needs for flexible generation
Renewable deployment continued accelerating across Bulgaria, Greece, Romania, Serbia and North Macedonia during the same timeframe. The region also saw increasing curtailment pressure in Greece alongside midday oversupply conditions. Solar growth in Bulgaria was paired with storage development plans, while Romania expanded renewable capacity amid grid bottlenecks.
The operating profile described for the system included daytime oversupply coexisting with evening scarcity, driven by solar and wind variability. Gas was presented as a bridge between these conditions because it can ramp quickly compared with coal and is not tied to hydrology compared with hydro generation . The role of flexible gas was also framed against limitations associated with current battery storage duration.
Coal phase-down plans run alongside gas corridor and LNG access projects
While regional gas infrastructure discussions have included diversification away from Russian supplies for several years, corridor planning is now also linked to electricity market stability requirements. The Vertical Gas Corridor and expanded interconnections across Greece, Bulgaria, Serbia and North Macedonia were cited in this context. Corridor relevance was also connected to potential changes in Russian pipeline flows into Europe.
TurkStream deliveries to Europe fell again in April, declining both month-on-month and year-on-year . Even as physical flows decreased, gas prices stayed elevated due to geopolitical volatility affecting global LNG markets tied to Middle Eastern disruptions and tighter supply competition. This combination was described as creating uncertainty for long-term procurement just as additional flexibility needs emerge for power system balancing.
Trading dynamics shift toward gas spreads, LNG flows and balancing fuel availability
The changing supply-demand balance also altered what factors influence regional electricity pricing behavior. Historically, traders focused on hydro conditions, coal availability and seasonal demand swings; going forward, gas spreads, LNG flows, storage levels and balancing fuel availability were described as increasingly influential. The correlation between gas hubs and Southeast European power exchanges was therefore said to be strengthening again.
In parallel with renewable expansion, utilities and governments pursued battery storage deployment alongside gas interconnection development and LNG access diversification . Coal phase-down strategies were also referenced together with grid modernization measures and balancing infrastructure investment. Rather than replacing gas immediately, renewable growth was described as temporarily increasing the strategic importance of flexible gas systems.
Sovereign flexibility strategies include interconnection, storage and demand response
The evolving market conditions were also reflected in how energy strategies were framed at country level within the region. Greece was described as positioned as a hub due to its LNG infrastructure, interconnection investments and expanding renewable base that place it at the center of emerging SEE energy corridors. Bulgaria’s role was linked to storage deployment and transmission positioning.
Serbia’s strategic importance was attributed to its central geographical position connecting Central Europe and the Balkans alongside future corridor expansions . Beyond electricity generation alone, industrial competitiveness—along with data center development—was cited as depending on reliable flexible energy supply rather than purely low-cost generation. Hydrogen projects, aluminum processing economics and regional export structures were also mentioned in connection with that requirement.
