Southeast European day-ahead power prices fell across most markets in week 33, as stronger solar generation and lower weekend demand weighed on baseload contracts, although persistent nuclear and hydro constraints kept evening hours tight and maintained a sizeable regional premium over western Europe.
Hungary averaged around EUR 145/MWh over 10-16 August, broadly aligned with Croatia and Slovenia, while Romania averaged about EUR 143/MWh. The tightly coupled central SEE cluster remained around EUR 24-26/MWh above the wider European average.
Prices were lower further south and east, with Bulgaria averaging around EUR 129/MWh, Serbia EUR 126/MWh and Greece EUR 102/MWh. Italy remained the principal high-price market connected to the region at about EUR 172/MWh, maintaining an incentive for exports from SEE towards the Italian system.
Week-on-week declines were nevertheless substantial. Hungarian prices fell around 7%, Romania and Croatia about 8%, while Bulgaria declined around 11%. Serbia dropped almost 19% and Greece about 25%.
The weekly averages, however, concealed considerably tighter conditions during evening hours.
Strong photovoltaic output increasingly pushed prices lower around midday before the loss of solar generation triggered sharp evening ramps. In Hungary on Thursday, prices moved from around EUR 84/MWh during the solar period to almost EUR 339/MWh in hour 21.
A similar pattern emerged on Friday, when Hungarian prices fell as low as EUR 30/MWh around midday before climbing above EUR 260/MWh in the evening.
Sunday widened the intraday divergence further. Hungarian prices dropped to about EUR 27/MWh during the middle of the day before rising above EUR 206/MWh later in the session. Bulgaria moved from around EUR 16/MWh to above EUR 205/MWh, while Serbia ranged from roughly EUR 10/MWh to more than EUR 180/MWh.
Greece recorded the strongest solar-driven price compression, with several consecutive daytime hours close to zero, followed by evening prices above EUR 200/MWh.
The pattern left conventional peakload indicators increasingly disconnected from the hours of greatest system stress. Hungarian peakload prices were below off-peak averages on several days because the standard peak block captured solar-rich daytime hours, while the off-peak period included increasingly expensive evening hours.
Nuclear, hydro constraints support evening premium
Supply-side constraints remained a key driver of the regional premium.
Hungary continued to face reduced availability at the Paks nuclear power plant, which normally provides close to 2 GW of capacity and accounts for roughly half of domestic electricity production.
Several Paks units had been affected by exceptionally low Danube water levels, while the gradual return of Unit 2 improved availability during the week. Hungary nevertheless remained heavily dependent on imports during tighter periods, taking close to 2 GW on average early in the week.
Romania faced similar problems at the Cernavoda nuclear plant. Unit 1 had already been disconnected because of exceptionally low Danube levels, while operator Nuclearelectrica started a controlled shutdown of Unit 2 on 13 August.
The loss of the two Cernavoda units removed around 1.4 GW of low-variable-cost nuclear capacity from the Romanian system, increasing reliance on coal, hydro, renewables and imports.
Hydrological conditions were also weak in Serbia. Output from Djerdap 1 was running at around 20% of normal levels, while Djerdap 2 was producing at roughly 30%, amid Danube inflows near historical lows. Serbian utility EPS consequently covered part of its requirements through market purchases.
The combination of weak hydro output and constrained nuclear generation increased the value of flexible capacity across the region, particularly after sunset.
Central SEE remains tightly coupled
Hungary, Romania, Croatia and Slovenia showed strong price convergence throughout the week. On six of the seven days, the difference between the highest and lowest prices within the four-market cluster remained below roughly EUR 3/MWh.
The tight coupling reduced opportunities for sustained country-to-country spreads within the central SEE block, while larger differentials remained against Greece, Bulgaria, Serbia and Italy.
Cross-border flows played an important balancing role. Hungary imported around 2 GW early in the week, although stronger renewable production subsequently improved the wider regional balance.
By Wednesday, higher wind and solar generation had shifted the combined SEE balance towards a small net export position, although Hungary itself remained a sizeable importer.
Italy continued to absorb electricity from the region because of its structurally higher price level. Flows towards the Italian market exceeded 1 GW during parts of the week, limiting the extent to which additional SEE renewable generation translated into lower regional prices.
Gas and carbon costs meanwhile maintained a relatively high thermal generation floor. Central European spot gas traded around EUR 57-62/MWh during the week, while EU carbon allowances remained near EUR 82-83/t.
Those inputs imply short-run generation costs for modern gas-fired plants broadly consistent with central SEE baseload prices around EUR 140-160/MWh, although they do not explain the evening spikes above EUR 250-300/MWh.
The latter increasingly reflected scarcity of flexible generation, transmission constraints and the rapid evening reduction in solar output.
Forward premium remains
The Hungarian forward curve continued to price regional tightness beyond the spot market. Week 34 traded around EUR 157/MWh late in the week, while September was near EUR 161/MWh, leaving Hungary roughly EUR 25-27/MWh above comparable German contracts.
Initial prices for Monday 17 August also pointed to a sharp recovery after the weekend decline.
Hungarian day-ahead power rebounded to around EUR 184/MWh, with Slovenia near EUR 181/MWh, Croatia EUR 181/MWh and Romania EUR 173/MWh. Bulgaria rose to approximately EUR 170/MWh, while Greece reached EUR 153/MWh.
The move suggests that week 33’s lower baseload averages were driven primarily by renewable output and weekend demand rather than a fundamental easing of the regional supply balance.
For short-term SEE trading, the widening difference between solar and evening hours is becoming more significant than the direction of baseload prices alone. Nuclear availability in Hungary and Romania, Danube hydrology, wind forecasts and cross-border capacity remain the principal variables for the evening curve, while growing photovoltaic output continues to increase downside pressure during daytime hours.
That divergence is also strengthening the economics of batteries and other flexible assets. Near-zero or very low midday prices alongside evening settlements above EUR 200/MWh are creating increasingly material intraday spreads even during weeks when the headline baseload contract appears comparatively stable.
