One of world’s deepest interconnections to enter commercial operation in two months

August 27, 2025, by Nadja Skopljak

The Crete-Attica electrical interconnection, the largest electricity transmission project in Greece, has completed a three-month testing phase, marking entry into the final stage before official commercial operation.

With a budget of over €1.1 billion, the cable link connects the Attica region on the Greek mainland to the Heraklion area in Crete, thanks to Nexans providing one 500 MW HVDC subsea cable system to form half of the bipole interconnection and Prysmian handling the other half of the interconnection and two subsea telecom links.

The interconnection, constructed by Ariadne Interconnection, a subsidiary of Greek transmission system operator (TSO) Independent Power Transmission Operator (IPTO or ADMIE), began operating on May 24, with the trial operation phase scheduled to last throughout the summer months.

IPTO reported on August 26 that the project had completed the three-month testing phase, confirming its capability for bidirectional energy flow under real operating conditions, and is now in continuous operation for the next two months, after which it will officially enter commercial operation.

“This milestone paves the way for the gradual decommissioning of polluting power plants on the island and the full integration of Crete into Greece’s unified electricity market model,” IPTO said.

The project ranks among the three deepest interconnections worldwide and with a capacity of 1,000 MW leads in power transfer capacity for island systems, ensuring energy security for Crete and reducing annual CO2 emissions by 500,000 tons.

It is co-financed by the Operational Programme “Transport Infrastructure, Environment and Sustainable Development” (NSRF 2014–2020) and the “Environment and Climate Change” program of NSRF 2021–2027, up to the amount of €535.5 million.