Southeast European electricity markets delivered another clear signal that the region is moving into a new trading environment where solar volatility, flexibility and infrastructure capacity are becoming the main drivers of value. Weekend demand combined with strong photovoltaic output pushed day-ahead prices sharply lower for Sunday delivery, while the following-day rebound showed that the weakness was primarily a temporary effect of lower consumption and renewable oversupply rather than a structural change in market fundamentals.
On Sunday, SEEPEX cleared at €72.62/MWh for baseload and €37.61/MWh for peak hours, with traded volume reaching 14,547.4 MWh. Regional prices remained relatively aligned, with Romania, Bulgaria and Greece averaging close to €80/MWh, Hungary around €81/MWh, Croatia at €82.27/MWh, and Slovenia approximately €84/MWh.
However, daily averages masked a much more extreme intraday pattern. Across Bulgaria, Greece, Hungary, Romania, Croatia and Slovenia, electricity prices dropped close to €0/MWh between 10:00 and 15:00 as solar generation peaked, before climbing toward €145/MWh during evening hours when photovoltaic output disappeared and demand remained elevated. The resulting spread of almost €145/MWh highlights the growing value of battery storage, flexible hydro, thermal capacity and cross-border transmission availability.
The market structure is increasingly shifting away from traditional baseload economics. The most valuable assets are becoming those capable of moving electricity through time: absorbing excess renewable production during low-price periods and supplying power during high-demand hours.
Serbia traded at a discount compared with neighbouring EU-coupled markets, with SEEPEX prices around €7–11/MWh lower. The lower price level reflected strong domestic supply conditions and regional solar-driven surplus during the low-demand Sunday session. Complete harmonised physical-flow data from all regional transmission operators were not yet available at the reporting deadline, preventing detailed bilateral flow analysis.
The weakness was short-lived. For Monday delivery, SEEPEX published a baseload price of €97.53/MWh, an increase of almost 34% from Sunday, while peak prices rose to €78.83/MWh and traded volume increased to 15,746.3 MWh. The recovery confirms that the weekend price decline was mainly caused by calendar effects and renewable output patterns rather than weaker Serbian fundamentals.
For renewable developers, the price curve provides another warning that annual average electricity prices are becoming an increasingly unreliable measure of project profitability. Merchant solar projects must now account for zero-price periods, curtailment risk, imbalance exposure and declining midday capture prices. Battery projects may benefit from large spreads, but commercial success depends on cycling limits, degradation management, balancing-market participation and the ability to generate revenue from multiple market segments.
Gas prices ease, but regional power markets remain exposed
European gas prices ended the week at €48.80/MWh on 10 July, down 2.91% on the day but still approximately 37% higher year on year. Earlier in the week, prices had increased by more than 12% due to renewed geopolitical concerns surrounding US-Iran tensions and potential risks to LNG flows through the Strait of Hormuz.
Brent crude closed at $76.01 per barrel, declining slightly on Friday but remaining around 5.5% higher over the week. Although LNG vessels continued passing through Hormuz, reduced shipping activity maintained a geopolitical risk premium. This leaves gas-fired generation in markets such as Greece and Romania vulnerable to fuel-price volatility even during periods of weak electricity demand.
Greece is becoming increasingly important as a regional gas hub. Total Greek gas consumption reached 43.09 TWh during the first half of 2026, up 15.06% year on year, while exports nearly tripled to 8.72 TWh from 2.86 TWh. Domestic demand remained relatively stable at 34.37 TWh.
The Revithoussa LNG terminal supplied 18.61 TWh, representing around 43% of incoming gas volumes, while flows through the Alexandroupoli FSRU increased more than threefold to 3.46 TWh. These figures demonstrate that Greek LNG infrastructure is increasingly supporting neighbouring markets, particularly Bulgaria and countries further north.
However, gas-fired power economics remain sensitive to LNG availability, transportation costs, transmission tariffs and geopolitical developments.
Vertical Gas Corridor moves toward commercial operation
Bulgaria’s role in regional energy security is expected to strengthen as infrastructure projects under the Vertical Gas Corridor move closer to completion. Bulgartransgaz expects key sections of the network to be ready by 1 October 2026, after which additional capacity will be offered through annual auctions.
Around 80% of the 48 km Kulata–Kresna pipeline section has already been welded and installed. The planned Rupcha–Vetrino expansion is designed to increase northbound transmission capacity and support the wider route connecting Greece, Bulgaria, Romania, Hungary, Slovakia, Moldova and Ukraine.
The corridor is now moving from strategic planning into a commercial utilisation phase. Its success will depend on long-term capacity bookings, competitive tariffs and actual market demand. For power generators and industrial consumers, it provides greater supply flexibility, while for infrastructure investors, contracted capacity will determine revenue security.
GEN-I expands regional battery storage strategy
Slovenian energy company and trader GEN-I is positioning itself as one of Southeast Europe’s leading storage operators, targeting approximately 800 MW of managed battery capacity by the end of 2026.
In Romania, GEN-I Sonce signed a turnkey agreement with Waldevar Energy for a 110 kV, 63 MVA substation and grid connection infrastructure supporting a planned 55 MW / 225 MWh battery storage project. Waldevar will provide engineering, procurement, construction, testing and commissioning services.
GEN-I has also expanded its Bulgarian portfolio through the acquisition of the Belovo, Momchilgrad and Parvomay 1 battery projects, with a combined capacity of 30 MW / 76 MWh. Together with the 12 MW / 24 MWh Kidričevo battery facility in Slovenia, the company now owns approximately 42 MW / 100 MWh of storage capacity and plans additional acquisitions.
The strategic advantage of GEN-I’s model lies in combining asset ownership, market access, aggregation and electricity trading. This allows batteries to participate in day-ahead, intraday, balancing and optimisation markets rather than relying only on simple price arbitrage.
Romania accelerates hybrid renewable development
Romania is entering a new phase of renewable investment, with several hybrid projects combining solar generation and battery storage moving into commissioning.
MORE, the renewable energy subsidiary of Motor Oil Hellas, placed the Stâlpu 2 hybrid project in Buzău County into trial operation. The facility combines 63 MW of solar capacity with a 10 MW / 21 MWh battery system and is expected to produce approximately 76 GWh annually.
The company has also started trial operations at the nearby Stâlpu 1 project, combining 48 MW of solar capacity with an 8 MW / 16 MWh battery.
These developments demonstrate the shift from standalone photovoltaic projects toward hybrid renewable assets designed to improve grid integration, reduce price exposure and provide greater control over electricity delivery.
The commissioning phase will be critical, requiring verification of battery performance, grid-code compliance, dispatch response, usable capacity and integration between solar generation, battery management systems, SCADA platforms and metering infrastructure.
Greek grid expansion supports renewable growth
Greek transmission operator IPTO completed the final phase of the Cyclades interconnection project, connecting Santorini, Folegandros, Milos and Serifos directly with the mainland electricity system through Attica.
The wider programme represents an investment of approximately €825 million, including the final phase valued at €385.7 million, which involved 294 km of 150 kV submarine and underground cables and four digital substations.
The project reduces dependence on expensive island diesel generation while creating additional capacity for renewable development. IPTO’s recent €1 billion capital increase further strengthens its ability to finance future grid expansion.
The project highlights a broader regional reality: renewable generation growth requires equally ambitious investment in transmission infrastructure.
Slovenia expands balancing markets and distributed solar
Slovenian transmission operator ELES joined the European PICASSO automated frequency-restoration reserve platform on 1 July and is preparing to connect to the MARI manual balancing platform on 15 July.
The move will expand access to balancing markets and allow technologies such as batteries, hydropower and flexible demand to participate in a larger European flexibility system.
At the same time, 25 Slovenian municipalities and public institutions completed 87 solar installations with combined capacity exceeding 6.3 MW, supported by a 232 kWh battery system. The projects are expected to generate approximately 6.6 GWh annually.
Although the storage component remains relatively small, the programme creates valuable experience in municipal renewable procurement, monitoring and operation.
Croatia creates framework for geothermal and carbon storage development
Croatia is creating a new legal framework covering hydrocarbons, geothermal energy and geological carbon storage. The government adopted legislation introducing new tender models, allowing existing wells and production fields to be repurposed for geothermal projects and CO₂ storage.
The framework could improve the economic potential of existing oil and gas infrastructure by transforming wells, geological data and facilities into new energy assets.
Commercial success will depend on reservoir performance, drilling costs, permitting processes and the availability of long-term contracts for geothermal heat, electricity generation or carbon storage.
Regional market outlook: Flexibility becomes the core investment theme
The latest market developments across Southeast Europe reinforce one central message: the future value of electricity infrastructure will increasingly come from flexibility.
Solar growth is creating larger intraday price swings, while storage, grid upgrades, balancing markets and hybrid renewable projects are becoming essential components of a reliable power system.
The region is moving toward a market where electricity is no longer valued only by how much is produced, but by when it is available, how quickly it can respond and whether it can be integrated into a more complex renewable-based system.