Southeast European day-ahead prices fell sharply for Sunday delivery as lower weekend demand combined with strong photovoltaic output. SEEPEX cleared at €72.62/MWh baseload and €37.61/MWh peak, with traded volume of 14,547.4 MWh. Romania, Bulgaria and Greece averaged close to €80/MWh, Hungary around €81/MWh, Croatia €82.27/MWh, and Slovenia approximately €84/MWh.
The baseload figures conceal a much more extreme hourly structure. Prices across Bulgaria, Greece, Hungary, Romania, Croatia and Slovenia fell to approximately €0/MWh between 10:00 and 15:00, before increasing to around €145/MWh during the late-evening hours. The resulting daily spread approached €145/MWh, confirming that value is increasingly concentrated in storage, dispatchable hydro, flexible thermal generation and evening cross-border capacity rather than undifferentiated baseload output.
Serbia traded at a discount of roughly €7–11/MWh to the coupled EU markets. This suggests that regional solar surplus and domestic supply conditions outweighed Serbia’s usual import dependence during the low-load Sunday session. Complete harmonised physical-flow data for 12 July were not yet available across all regional TSOs at the publication cut, so no unsupported bilateral flow estimates are included.
The weakness is already reversing for Monday. SEEPEX has published a 13 July baseload price of €97.53/MWh, up almost 34% from Sunday, with peak load at €78.83/MWh and traded volume rising to 15,746.3 MWh. The rebound indicates that the weekend price collapse is primarily a calendar-and-solar effect rather than a sustained loosening of Serbian fundamentals.
For merchant solar, Sunday’s curve is another warning that annual average prices are becoming a poor proxy for achievable revenue. Capture-price models now need explicit assumptions for zero-price hours, curtailment, imbalance exposure and storage charging. For BESS projects, the gross spread remains attractive, but bankability depends on cycling limits, degradation, balancing-market access and the ability to capture more than a simple day-ahead arbitrage margin.
Gas premium eases but remains a material power-price risk
European gas ended the week at €48.80/MWh on 10 July, down 2.91% on the day but still 37.23% higher year on year. Prices had risen by more than 12% during the preceding three sessions as renewed US-Iran hostilities increased concern over LNG traffic through the Strait of Hormuz.
Brent crude settled at $76.01/bbl, down 0.38% on Friday but around 5.5% higher over the week. LNG carriers continued to pass through Hormuz, although overall shipping traffic remained reduced. The combination leaves gas-fired generation in Greece, Romania and other SEE markets exposed to a geopolitical premium even when weekend power demand is weak.
Greece’s position as the southern entry point for regional gas is strengthening. Total Greek gas demand reached 43.09 TWh during the first half of 2026, an increase of 15.06% year on year, while exports tripled to 8.72 TWh from 2.86 TWh. Domestic consumption was broadly unchanged at 34.37 TWh. The Revithoussa LNG terminal supplied 18.61 TWh, or 43% of incoming volumes, while flows through the Alexandroupoli FSRU more than tripled to 3.46 TWh.
The figures show that Greek LNG infrastructure is increasingly supporting Bulgaria and markets further north rather than serving only domestic demand. This improves regional supply diversification, but gas-fired power economics remain sensitive to terminal utilisation, transmission tariffs, LNG shipping costs and short-term geopolitical disruptions.
Vertical Gas Corridor moves closer to capacity-delivery stage
Bulgartransgaz expects the Bulgarian infrastructure forming part of the Vertical Gas Corridor to be completed by 1 October 2026, after which increased transmission capacity is intended to be offered through annual auctions.
Around 80% of the pipes on the 48 km Kulata–Kresna section have been welded and laid. Work on the Rupcha–Vetrino loop is intended to raise capacity towards Romania, supporting the broader northbound route linking Greece, Bulgaria, Romania, Hungary, Slovakia, Moldova and Ukraine.
The corridor is moving from strategic-policy status into an infrastructure utilisation test. Its economic value will depend on binding capacity bookings and competitive tariffs. For gas-fired power generators and industrial users, the asset improves supply optionality; for transmission operators and lenders, contracted throughput remains the critical revenue variable.
GEN-I builds a regional storage and flexibility platform
Slovenian utility and trader GEN-I expects to manage 800 MW of large-scale battery capacity by the end of 2026, marking one of the region’s most ambitious storage-aggregation strategies.
In Romania, GEN-I Sonce signed a turnkey agreement with Waldevar Energy for a 110 kV, 63 MVA Gheorgheni substation and associated 110 kV grid connection. The package forms the first phase of a 55 MW / 225 MWh BESS. Waldevar’s scope includes engineering, procurement, construction, testing and commissioning, while GEN-I has indicated that two additional Romanian battery investments are being developed.
GEN-I has also acquired the operational Belovo, Momchilgrad and Parvomay 1 battery projects in Bulgaria, with combined capacity of 30 MW / 76 MWh. Together with the 12 MW / 24 MWh Kidričevo facility in Slovenia, its owned portfolio has reached 42 MW / 100 MWh. The company aims to add another 100 MW through acquisitions before year-end.
The strategy is commercially important because GEN-I combines asset ownership, market access, aggregation and trading. This gives batteries access to day-ahead, intraday, balancing and portfolio-optimisation revenues rather than relying on one arbitrage stream. For lenders, the key due-diligence areas will be performance guarantees, availability, degradation, connection commissioning and the contractual allocation of merchant revenue risk.
Romanian hybrid plants enter the commissioning phase
MORE, the renewable-energy subsidiary of Motor Oil Hellas, has 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 and is expected to generate approximately 76 GWh annually. MORE owns 80%, with Alive Renewable Holding, part of Premier Energy Group, holding the remaining 20%.
The nearby Stâlpu 1 project has also entered trial production, combining 48 MW of solar with an 8 MW / 16 MWh BESS. The two projects demonstrate the shift in Romania from standalone photovoltaic development towards hybrid assets designed to manage grid injection and price exposure.
Trial operation is now the critical value-conversion stage. Investors will need evidence that the batteries can comply with grid-code requirements, respond to dispatch instructions, deliver guaranteed usable capacity and operate without accelerating degradation. Owner’s Engineer oversight is particularly relevant during integrated testing of the solar plant, battery management system, power-conversion system, SCADA, protection and metering interfaces.
Cyclades interconnection strengthens Greek grid investment case
Greek transmission operator IPTO has completed the final phase of the Cyclades interconnection programme linking Santorini, Folegandros, Milos and Serifos directly to the mainland system through Attica.
The wider programme has a combined budget of €825 million. Its fourth phase was valued at €385.7 million and included 294 km of 150 kV submarine and underground cables and four digital gas-insulated substations. IPTO has also completed a €1 billion share-capital increase, reinforcing its financing capacity for additional interconnectors.
The links reduce reliance on expensive island oil and diesel generation while creating additional space for renewable development. They also illustrate the scale of regulated grid investment required before high-renewables markets can translate nominal generation pipelines into bankable connected capacity.
Slovenia expands balancing integration and distributed generation
Slovenian TSO ELES joined the European PICASSO platform for automated frequency-restoration reserves on 1 Julyand is preparing to connect to the MARI manual-reserve platform on 15 July. Cross-border balancing integration should broaden the pool of available reserves and allow Slovenian providers—including batteries, hydro and flexible demand—to compete in a larger market.
Separately, 25 Slovenian municipalities and public institutions completed 87 solar installations with total capacity exceeding 6.3 MW, supported by a 232 kWh battery system. The installations are expected to generate around 6.6 GWh annually, with full commissioning scheduled by the end of July.
The relatively small battery component indicates that the programme is primarily a self-consumption and public-energy-cost project rather than a major flexibility investment. Its larger significance is the creation of replicable procurement, metering and operating models for municipal portfolios.
Croatia opens new framework for geothermal and carbon storage
The Croatian government adopted a bill on 10 July establishing a unified framework for hydrocarbons, geothermal resources and geological carbon-dioxide storage.
The proposed legislation introduces new tender models, allows existing wells and production fields to be repurposed for geothermal energy or CO₂ storage, and permits parallel or successive use of the same geological area for different energy resources.
The framework could improve the economics of depleted oil and gas infrastructure by converting existing wells, geological data and surface facilities into geothermal-heating, electricity-generation or CCS assets. Commercial progress will still depend on reservoir performance, drilling risk, permitting and the availability of long-term heat or carbon-storage contracts.
