Slovenia and Italy to upgrade electricity interconnectors

Slovenian transmission and distribution system operator ELES and Italian transmission system operator Terna agreed to upgrade their cross-border electricity network in an investment of EUR 250 million. The project aims to increase the transmission capacity between the two countries by 600 MW, strengthening supply and trade.

After a decade of coordination, ELES and Terna signed an agreement to raise the electricity transmission capacity between Slovenia and Italy by 600 MW or more than 50%. According to ELES, it is an important step in market integration and strengthening the reliability of the interconnected electricity system.

Interconnections between Slovenia and Italy are currently among the most heavily loaded ones in the Slovenian network, the country’s TSO pointed out.

As ELES further explained, with the growth of electricity imports and exports, there is an increasing need to strengthen transmission routes between the two countries. The company expects a rise in electricity imports in the countries gradually phasing out fossil fuel–based production to further increase the demand for cross-border transmission capacity.

The project consists of three upgrades

The project includes three main improvements. On the Slovenian side, the phase-shifting transformer at the Divača substation would be upgraded, alongside adding a third unit, which enables full utilization of the capacity of the 400 kV transmission line between Divača and Redipuglia (Sredipolje). The current transmission capacity, 1,200 megavolt-amperes (MVA), would be lifted to 1,800 MVA.

On the 220 kV transmission line between Divača and Padrice in Italy, low-sag conductors, capable of withstanding higher temperatures will be installed, ELES said. The transmission capacity would be doubled to 700 MVA.

On the Italian side, the existing 220 kV Padriče-Redipuglia connection and the Redipuglia substation are to be upgraded with a new phase-shifting transformer. It is crucial for managing internal power flows, the update reads.

“With an additional 600 MW 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,” said ELES CEO Aleksander Mervar.

Slovenia’s share of the project is estimated at EUR 90 million

The total value of the project is EUR 250 million, with the Slovenian share estimated at EUR 90 million and the Italian side securing EUR 160 million. Pending all necessary permits and documentation, construction is planned to begin in 2029, and completion is expected by the end of 2031.

ELES announced it would seek European funds to finance the Slovenian side of the investment.

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