A drastic drop in electricity generation from nuclear and hydropower plants, coupled with surging demand due to extreme heatwaves, has pushed power exchange prices in Southeast Europe above EUR 700 per megawatt-hour over the past week. Several countries are now facing an energy crisis.
Prices were the highest on exchanges in Slovenia and Croatia, while the lowest were seen in Greece and Bulgaria. The highest price in the region, of EUR 717 per MWh, was recorded on the Slovenian exchange BSP Southpool on August 3 between 20:00 and 20:15, according to an analysis by Balkan Green Energy News.
The analysis examined day-ahead market (DAM) prices across seven Southeast European exchanges for the period from July 31 to August 6, based on 15-minute intervals. Compared to previous weeks, prices rose by an average of 50-100%.
The power exchanges included in the study were BSP Southpool (Slovenia), CROPEX (Croatia), HEnEx (Greece), HUPX (Hungary), IBEX (Bulgaria), OPCOM (Romania), and SEEPEX (Serbia). The ten highest prices were ranked for each of the seven exchanges.
August 3 and 4 – last Monday and Tuesday – saw the highest frequency of price spikes. Overall, prices increased by 50–100% compared to preceding weeks.
The highest prices were concentrated in four 15-minute market time units (MTUs): 19:30–19:45, 19:45–20:00, 20:00–20:15, and 20:15–20:30. These intervals coincide with a drop in solar power generation as the sun sets and electricity demand remains high or continues to climb.
The generation-consumption balance nas been disrupted
Although further in-depth analyses will yield more detailed insights, the lowest prices were consistently recorded in Greece and Bulgaria – the two countries with the highest solar and battery capacities. Greece boasts 9 GW of solar power and 1 GW of battery energy storage systems (BESS), while Bulgaria has 6 GW of solar and 3.7 GW of batteries- the world’s No. 1 in BESS share.
However, prices surged due to a severe supply-demand imbalance: power output dropped sharply just as consumption surged.
Low water levels on the Danube forced Hungary’s Paks nuclear power plant to curtail production by 90%, Romania’s Cernavodă to cut output by 50%, and Slovenia’s Krško to reduce capacity by 20%. With river levels not expected to rise anytime soon and high temperatures persisting, further generation cuts remain a distinct possibility.
Hydropower plants are also struggling. In Serbia, the Đerdap 1 hydropower plant is operating at just 20% of its normal output, while Đerdap 2 is producing 30%. On top of that, Montenegro’s Pljevlja thermal power plant was offline for several days.
On the demand side, electricity consumption across the region rose by between 5% and 20%.
Slovenia
The Krško nuclear power plant generates 35–38% of Slovenia’s electricity and covers roughly 35% of its total consumption. A few days ago, high water temperatures in the Sava River forced the plant to scale back output, as environmental regulations prohibit thermal discharge from elevating river temperatures above set safety thresholds.
Croatia
The output reduction at Krško also impacted Croatia, which receives half of the plant’s electricity generation – an amount that covers 15–20% of the country’s power needs.
Romania
Romania has resorted to unconventional measures to keep the Cernavodă nuclear plant operational, including sinking barges to raise the Danube’s water levels. The plant accounts for about a fifth of the country’s total electricity generation and covers an equivalent share of total demand.
Serbia
Electricity in Serbia was the most expensive between 19:00 and 19:30, with the highest number of price peaks on the SEEPEX exchange seen on August 3.
Hungary
Unable to draw sufficient cooling water from the Danube, the Paks nuclear power plant throttled its 2,000 MW capacity down to approximately 230 MW. Under normal conditions, the facility supplies 45–50% of Hungary’s total electricity generation, covering about a third of national demand.
Bulgaria
Despite being located on the Danube, the Kozloduy nuclear power plant experienced no operational disruptions thanks to its technical design, which allows it to secure enough cooling water even during low river levels.
Greece
Along with Bulgaria, Greece experienced its highest price spikes on August 5, whereas all other analyzed exchanges peaked on August 3 or 4.
