ELES and Terna Partner to Invest $291.08 Million to Upgrade Cross-Border Electricity Connection between Slovenia and Italy

ELES and Terna, the Slovenian and Italian transmission system operators, have signed an agreement to invest approximately $291.08 million to increase transmission capacity and promote market integration by 600 MW.

With the planned upgrades, the two companies will increase cross-border transmission capacity by an additional 600 MW, representing more than a 50% increase in physical transmission capacity between Slovenia and Italy.

The planned interventions include:

• 400 kV Divaca – Redipuglia: The existing Phase Shifting Transformer at the Divaca substation will be upgraded with a new third unit, enabling full transmission capacity of the 400 kV line between Divaca and Redipuglia. Current transmission capacity is 1200 MVA, which will increase to 1800 MVA upon project completion.
•  220 kV Divaca – 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.
•  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 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. ELES will apply for EU funding to finance the investments on the Slovenian side.

The international electricity connections between Slovenia and Italy are among the most heavily loaded cross-border links in the Slovenian power system. The 400 kV Divaca–Sredipolje and 220 kV Divaca–Padriciano lines 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 crucial. With countries 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 help with stable operations and greater flexibility in the regional electricity market. The project will allow for more efficient management of cross-border flows and long-term energy security for both countries and the region.

“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,” said Enrico Maria Carlini, Head of Power System Planning and Permitting at Terna. “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.”