Today, ELES and Terna, the Slovenian and Italian transmission system operators, signed an agreement outlining a joint investment of approximately €250 million to increase transmission capacity and promote market integration by 600 megawatts. The project is expected to be completed by 2031.
After a decade of coordination, Slovenia’s combined transmission and distribution system operator, ELES, and Italy’s transmission system operator (TSO), Terna, have signed an agreement to upgrade the cross-border electricity connection between Slovenia and Italy. The project marks a significant step toward deeper market integration and strengthening the adequacy of the interconnected power system.
With the planned upgrades, the two companies will increase cross-border transmission capacity by an additional 600 megawatts, representing more than a 50% increase in physical transmission capacity between Slovenia and Italy.
€250 Million for Three Key Upgrades
The planned interventions include:
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400 kV Divača – Redipuglia: The existing Phase Shifting Transformer at the Divača substation will be upgraded with a new third unit, enabling full transmission capacity of the 400 kV line between Divača and Redipuglia. Current transmission capacity is 1200 MVA, which will increase to 1800 MVA upon project completion.
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220 kV Divača – Padriciano: The existing Phase Shifting Transformer at the Padriciano substation and the conductor on this 220 kV line will be upgraded using low-sag conductor technology. Current transmission capacity is 350 MVA, which will double to 700 MVA after the upgrade.
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On the Italian side, the existing 220 kV Padriciano–Redipuglia connection and the Redipuglia substation will be upgraded with a new Phase Shifting Transformer installed inland in Italy. This will be crucial for managing internal power flows.
Construction is expected to begin in 2029, following the acquisition of all necessary permits and documentation, with project completion planned by the end of 2031. The total investment is estimated at approximately €250 million. ELES will apply for EU funding to finance the investments on the Slovenian side.
Why Is the Project Necessary?
The international electricity connections between Slovenia and Italy are currently among the most heavily loaded cross-border links in the Slovenian power system. The 400 kV Divača–Sredipolje and 220 kV Divača–Padriciano lines already carry high power flows, highlighting the need for upgrades and capacity expansion. As import and export flows continue to grow, the need to strengthen transmission routes between Italy and Slovenia becomes even more pressing. With countries gradually phasing out fossil fuel-based generation, electricity imports are expected to rise, increasing the demand for robust cross-border transmission infrastructure.
Through this project, ELES and Terna are contributing to improved cross-border transmission capacity and greater grid resilience. The increased capacity will enable more stable operations and greater flexibility in the regional electricity market. The project is a step toward comprehensive grid modernization, which, with continued investment, will allow for more efficient management of cross-border flows and long-term energy security for both countries and the region.
Statements from ELES and Terna
Mag. Aleksander Mervar, CEO of ELES, emphasized at the signing:
“This project goes beyond a mere technical upgrade—it represents a tangible realization of European energy solidarity on one hand, and ELES’s long-standing efforts to strengthen international energy connections on the other. With an additional 600 megawatts of cross-border capacity, Slovenia is solidifying its role as a key electricity hub between Central and Southern Europe and as a reliable regional partner. This is a strategic investment in the future, ensuring reliability, resilience, and connectivity of our grid in the decades when electricity will become the main energy currency.”
Enrico Maria Carlini, Head of Power System Planning and Permitting at Terna, added:
“I am pleased that these measures reinforce our long-standing high-level cooperation. The agreement not only strengthens the historic partnership between the two transmission system operators but also marks an important step toward developing and implementing innovative solutions that enhance the efficiency of transmission network investments. The agreement encourages system operators to introduce not only capital-intensive projects but also solutions with lower capital requirements that can increase net benefits and investment returns for all electricity system users.”