ADMIE has completed construction of the southern Cyclades interconnection, a project that integrates the islands of Santorini, Folegandros, Milos, and Serifos into the mainland power grid via Attica.
This is the fourth and final phase of the broader Cyclades interconnection project, through which—since 2018—the islands of Paros, Mykonos, Syros, and Naxos have been directly connected to the high-voltage grid, and the Euboea-Andros and Andros-Tinos submarine cable connections have been upgraded.
As noted in the relevant announcement, the interconnection of the southern Cyclades was achieved using 150 kV high-voltage submarine and underground cables, approximately 294 km in length. The submarine cables were laid at a maximum depth of over 500 meters below sea level, and as part of the project, ADMIE constructed four fully digitized gas-insulated switchgear (GIS) substations to connect the power cables to the islands’ local distribution networks.
On Santorini, an automatic reactive power compensation system (SVC) was also installed—infrastructure specifically designed to maintain voltage stability and optimize the operation of the interconnected grid in the southern Cyclades.
The electrical interconnection of the southern Cyclades, with a total budget of 385.7 million euros, is a project of strategic importance for the islands’ energy security, especially during periods of high demand recorded during the summer months due to increased tourist traffic.
With the completion of construction work, the project is now entering the final phase of testing and inspections. To ensure the smooth operation of existing interconnections, the new lines will be gradually integrated into the National Electricity Transmission System, starting with Santorini, taking into account the current tourist season. Full electrification of the entire interconnection will be completed within the next few months.
The electrical interconnection of the Cyclades ends the energy isolation of many islands, which are now directly or indirectly connected to the mainland grid, contributing significantly to sustainable development and the enhancement of the tourism product.
The decommissioning of polluting power plants that use fuel oil for local electricity generation also offers significant environmental benefits for the Aegean ecosystem due to reduced CO2 emissions, as well as savings for consumers throughout the country due to lower utility bills.
The project has been designated by Ministerial Decision as “of general importance to the country’s economy,” and its construction is funded by EU resources totaling 164.5 million euros through the Recovery and Resilience Facility, Greece 2.0.
The European Investment Bank is also participating in the project’s financing through a direct loan agreement of 157 million euros entered into by ADMIE, as well as through a second loan agreement worth 108.44 million euros, which was supported by funds from the Recovery and Resilience Facility, Greece 2.0.