Day-ahead electricity prices across much of Central and Southeast Europe fell to zero or negative levels during Sunday’s solar peak, before rebounding to above €225/MWh in the evening. The pattern was visible across multiple markets, with midday pricing shifting sharply within the same day.
Negative midday pricing across several Southeast European markets
Hungary, Romania, Slovenia and Croatia recorded negative prices around midday, while Bulgaria and Greece traded around zero for several hours. The move coincided with strong renewable output meeting lower weekend demand.
In Hungary, power averaged about €113.8/MWh, dropped to around -€1.5/MWh at 13:00, and then rose to roughly €227.7/MWh at 20:00. Romania followed a similar curve, falling to around -€1/MWh before reaching about €227.7/MWh in the evening.
Slovenia fell to -€1.18/MWh and Croatia to around -€0.93/MWh. Bulgaria and Greece later climbed to roughly €225-227/MWh, aligning with the evening rebound seen elsewhere in the region.
Regional coupling limits flexibility when oversupply is simultaneous
The simultaneous shift indicated that solar-driven oversupply was becoming a regional rather than isolated national event. Interconnectors can redistribute excess generation, but their ability to absorb it declines when neighbouring markets are oversupplied at the same time.
After sunset, the reverse pattern occurred as solar output declined across the region simultaneously. That decline increased demand for hydro, gas and nuclear generation, as well as batteries and imports, pushing competing markets toward a shared pool of flexible supply.
The resulting intraday spreads supported stronger economics for battery storage and reservoir hydro while also increasing price cannibalisation for standalone solar. Electricity that was worth zero around midday reached more than €225/MWh several hours later in some markets.
Serbia’s different pricing profile on September 6 session
Serbia remained the main outlier as other Central and Southeast European markets moved through negative midday levels into high evening prices. The SEEPEX contract averaged about €60.2/MWh, down roughly 47% day on day.
The SEEPEX session also showed an evening peak near €134/MWh, substantially below Central and eastern SEE markets. The divergence pointed to continuing congestion and differences in national supply balances despite broader regional coupling.
The Sept. 6 session reinforced a structural shift already visible across Southeast Europe, where additional solar capacity increasingly produces cheap daytime electricity without removing expensive evening scarcity. The region is producing enough renewable electricity to drive daytime price drops, but still lacks sufficient storage, flexible demand and dispatchable capacity to move that output into the hours when it is most valuable.