Day-ahead electricity prices across much of Central and Southeast Europe fell to zero or negative levels during Sunday’s solar peak before rebounding above €225/MWh in the evening, highlighting a growing shortage of system flexibility.
Hungary, Romania, Slovenia and Croatia all recorded negative prices around midday, while Bulgaria and Greece traded near zero for several hours as strong renewable generation coincided with weaker weekend demand.
Hungarian power averaged around €113.8/MWh, falling to approximately -€1.5/MWh at 13:00 before climbing to about €227.7/MWh at 20:00.
Romania followed a similar pattern, with prices dropping to around -€1/MWh before reaching approximately €227.7/MWh in the evening. Slovenia fell to -€1.18/MWh, while Croatia reached around -€0.93/MWh. Bulgaria and Greece later climbed to roughly €225-227/MWh.
The simultaneous price movements indicate that solar-driven oversupply is increasingly becoming a regional phenomenon rather than an isolated national event.
Interconnectors can help redistribute surplus generation, but their ability to absorb excess power is limited when neighbouring markets experience oversupply at the same time.
The market dynamic reverses after sunset.
As solar generation declines across the region simultaneously, demand for hydro, gas and nuclear generation, batteries and imports increases, pushing interconnected markets toward the same limited pool of flexible supply.
These sharp intraday price spreads are improving the economics of battery storage and reservoir hydropower, while increasing the price-cannibalisation pressure facing standalone solar projects.
Electricity priced at around zero euros per MWh at midday was worth more than €225/MWh only several hours later in some markets, underlining the growing value of shifting generation across time.
Serbia remained the main regional outlier.
SEEPEX averaged around €60.2/MWh, down roughly 47% day on day, while the evening peak reached approximately €134/MWh—substantially below price levels recorded across Central and eastern Southeast European markets.
The divergence highlights persistent congestion and differences in national supply-demand balances despite broader regional market coupling.
The September 6 trading session reinforces a structural shift already emerging across Southeast Europe: continued solar expansion is increasingly producing very cheap electricity during daylight hours without eliminating periods of expensive evening scarcity.
For investors, the key market signal is therefore shifting away from the traditional daily baseload price toward the value of flexibility.
The region is increasingly capable of producing sufficient renewable electricity, but it still lacks enough storage, flexible demand and dispatchable capacity to shift that energy into the hours when it has the greatest value.
