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Folegandros island joins Greece's mainland power grid via subsea cable

Folegandros island joins Greece's mainland power grid via subsea cable

Built World

60-kilometer cable ends the island's energy isolation as part of the Southern Cyclades interconnection

Today: Folegandros connected to mainland power grid

Overview

Updated 1 hour ago

Folegandros, a small island in the Aegean Sea, now draws its electricity from Greece's mainland power grid. A 60-kilometer subsea high-voltage cable connects it to Santorini and Naxos, ending decades of reliance on local diesel generators.

The connection is part of the €385.7 million Southern Cyclades interconnection project, the fourth and final phase of a program to integrate the entire Cyclades island group into the national high-voltage grid. The project includes 294 kilometers of submarine and underground cables and four digital gas-insulated substations.

Why it matters

Folegandros residents get reliable, cheaper electricity, and the island's polluting diesel generators can be switched off for good.

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Key Indicators

€385.7M
Southern Cyclades project budget
Total budget for the fourth and final phase of the Cyclades interconnection program.
60 km
Folegandros subsea cable length
Length of the high-voltage cable connecting Folegandros to Santorini and Naxos.
294 km
Total cable length
Combined submarine and underground cables in the Southern Cyclades project.
150 kV
Cable voltage
High-voltage alternating current cable with integrated optical fibers.
200,000 tons
Estimated annual CO2 reduction
Projected emissions reduction across the Cyclades from retiring diesel power plants.
600 MW
Renewable energy development space
Grid capacity expected to open for renewable energy projects on interconnected islands.

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People Involved

Organizations Involved

Timeline

June 2026 October 2026

2 events Latest: Today
  1. Folegandros connected to mainland power grid

    Today Infrastructure

    The 60-kilometer subsea cable linking Folegandros to Santorini and Naxos was energized, connecting the island to Greece's mainland high-voltage grid.

  2. Southern Cyclades interconnection construction completed

    Infrastructure

    IPTO completed construction of the Southern Cyclades interconnection, connecting Santorini, Folegandros, Milos, and Serifos to the mainland grid via Attica.

Scenarios

1

Southern Cyclades fully energized by mid-2027

Likely Resolves by Q2 2027

Discussed by: IPTO announcements

IPTO has said the energization of Santorini, Milos, and Serifos will follow "in the coming period." If the remaining islands are connected without major delays, the full Southern Cyclades project will be operational, completing the integration of the Cyclades into the mainland grid.

2

Diesel plants retired across the Cyclades

Likely Resolves by End of 2027

Discussed by: Greek Ministry of Environment and Energy

The interconnection is designed to allow the phase-out of polluting diesel power plants on the interconnected islands. If the grid connection proves reliable, the old plants will be decommissioned, cutting CO2 emissions by an estimated 200,000 tons annually across the Cyclades.

3

Renewable energy development accelerates on the Cyclades

Possible Resolves by End of 2028

Discussed by: IPTO, Greek energy analysts

The interconnection frees up grid capacity for renewable energy projects. IPTO estimates the electrical space for renewable energy development will exceed 600 MW across the Cyclades. If developers move quickly, the islands could see a wave of solar and wind projects in the coming years.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

2018-2024

Earlier Cyclades interconnection phases (2018-2024)

The Cyclades interconnection program has been rolling out in phases. Earlier phases connected the northern and central Cyclades islands, including Mykonos, Paros, and Naxos, to the mainland grid through a series of subsea cables and new substations.

Then

Each phase followed the same pattern: subsea cables, new substations, and gradual retirement of local diesel generation.

Now

The program established a proven template for island grid integration that Phase 4 is now completing.

Why this matters now

The Southern Cyclades project is the final phase of this program, applying the same approach to the remaining islands.

Ongoing

Crete-Attica interconnection (ongoing)

Greece is also building a major subsea interconnection to connect Crete, the country's largest island, to the mainland grid. The project involves long-distance, deep-water cable laying and is one of the most technically challenging grid projects in the Mediterranean.

Then

The project is expected to end Crete's reliance on local oil-fired power plants.

Now

It demonstrates Greece's broader strategy of integrating all major islands into the national grid.

Why this matters now

The Southern Cyclades project shares the same technical approach and strategic goal as the Crete interconnection.

Sources

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