Day-ahead electricity prices across much of Central and Southeast Europe fell to zero or negative levels during Sunday’s solar peak. Prices then rebounded above €225/MWh in the evening. The pattern was linked to a period of strong solar output and lower weekend demand.
Midday negative pricing across several SEE markets
Hungary, Romania, Slovenia and Croatia posted negative prices around midday. Bulgaria and Greece traded around zero for several hours as renewable generation increased. The same session showed that the price move occurred across multiple markets rather than remaining confined to one country.
In Hungary, power averaged about €113.8/MWh. Prices fell to around -€1.5/MWh at 13:00 before rising to roughly €227.7/MWh at 20:00. Romania followed a similar curve, dropping to around -€1/MWh before reaching about €227.7/MWh in the evening.
Slovenia fell to -€1.18/MWh, while Croatia traded around -€0.93/MWh. Bulgaria and Greece later climbed to roughly €225-227/MWh. Serbia remained the main outlier during the same trading window.
Regional oversupply reduces flexibility during the solar peak
The simultaneous move indicated that solar-driven oversupply was becoming a regional event rather than isolated within individual national systems. Interconnectors can redistribute excess generation, but their ability to absorb it falls when neighbouring markets are oversupplied at the same time. After sunset, the reverse effect occurred as solar output declined.
As output dropped across the region simultaneously, demand for hydro, gas, nuclear generation, batteries and imports increased. Competing markets moved toward a shared pool of flexible supply. This shift affected intraday spreads between low-price daytime hours and higher-value evening periods.
SEEPEX falls while evening peaks remain below other markets
The intraday price spreads supported stronger economics for battery storage and reservoir hydro while increasing price cannibalisation for standalone solar. Electricity that traded at zero around midday was worth more than €225/MWh several hours later in some markets.
The SEEPEX market averaged about €60.2/MWh, down roughly 47% day on day. Its evening peak was near €134/MWh, substantially below Central and eastern Southeast Europe markets.
The divergence pointed to continuing congestion and differences in national supply balances despite broader regional coupling. The Sept. 6 session reinforced a structural change already visible across Southeast Europe: additional solar capacity increasingly produced cheap daytime electricity without removing expensive evening scarcity.
The signal for market participants therefore shifted from daily baseload levels toward the value of flexibility as solar output rose and fell within the same day. The region continued to produce enough renewable electricity, but still lacked sufficient storage, flexible demand and dispatchable capacity to move that generation into the hours when it is most valuable.
