Tilos became the first Greek island to approach energy self-sufficiency when a smart renewable energy microgrid and battery was installed in 2017.
An initial attempt had been made in 2012, after Greece’s Centre for Renewable Energy Systems (CRES) invited island proposals to go green. A change in the program meant Tilos did not follow through, but “we didn’t stop trying to pursue our renewable energy idea,” said Mayor Maria Kamma.
Tilos tried again in 2013, responding to an EU call for proposals for hybrid energy systems for islands, under the bloc’s Horizon 2020 research program.
“We are talking about an energy revolution,” said Kamma. “Greece didn’t have … a legal framework allowing the operation of hybrid energy systems … the electric utility was also not allowed to buy electricity from a hybrid power station.”
With funds secured, Greece’s government developed the necessary policy and licenses were secured with the help of the University of Western Attica in Athens.
Off the main Greek grid, Tilos, with its 500 permanent residents, is part of a small network with neighboring Kos and Kalymnos. The original plan was for a hybrid system to top up Kos’ diesel generators. Tilos negotiated for two years to raise the ambition to a microgrid that supported standalone and grid operation.
“Tilos now has access to electricity even when the subsea cable or the diesel generators in Kos are out of order,” said Kamma. “Other islands, often bigger than Tilos, face regular blackouts.”
Tilos Deputy Mayor Spiros Aliferis said the island’s 800 kW/2.8 MWh battery storage system stabilizes the grid, can export power to Kos and Kalymnos, and provides ancillary services to Kos’ grid.
Business models
Kamma and Aliferis wanted Tilos council to own the system, but the community did not have the funds to buy it. Greek renewables developer Eunice Energy Group stepped in, funding the project’s 160 kW of solar capacity and 800 kW of wind power equipment, and now owns the system. The EU funded the rest, which involved 13 organizations from seven nations.
Eunice said its Tilos site had generated 8.7 GWh through November 2024, covering around half the island’s 17.2 GWh demand during that period. The system meets around 70% of winter demand and sometimes exceeds daily requirements.
“We are very happy that Eunice, a Greek firm, stepped in to fill the financing gap for the PV and wind systems,” said Kamma. “However, in the future, we believe that similar projects should also offer financial incentives directly to local residents.”
Eunice sells the electricity to the local grid with different rates for power from the batteries, solar, and wind facilities. The former is the most expensive. The developer said it would be happy to sell directly to residents, but is bound to deal with the grid, as per the rules of the state-controlled utility, Public Power Corp.
The council on nearby Halki island installed a privately sponsored 1 MW solar array in 2021, which benefits from net metering payments from the Rhodes grid. Set up as an energy community, the Halki system generates electricity for its community members.
Gr-Eco Islands
The government’s Gr-Eco Islands Initiative targets 80% emissions reduction for non-mainland-grid islands by 2030.
The initiative became law in 2022, enabling private donors to help sponsor the program, as eco-conscious businesses did on Halki. On the island of Astypalaia, Volkswagen’s smart mobility program encourages residents to adopt electric vehicles (EVs). United Arab Emirates state-owned developer Masdar is set to sponsor a PV array and energy community on Poros.
A spokesperson for Greece’s Ministry of the Environment and Energy (Ypen) said most of the Gr-Eco funds would come from the €150 million ($159 million) EU Structural and Investment Funds pot for 2021 to 2027 and Greece’s island decarbonization fund, which is backed by emission trading income. Progress has been slow, amid confusion over the island program.
Mayor Kamma said the island has proceeded on its own, attracting European funds outside of Gr-Eco. There was no initiative when Tilos started its decarbonization journey, she said. “Thus, we attracted EU funds that allowed us to build the hybrid energy system, replace about all of the council’s fleet with EVs, install EV chargers, buy two electric buses and set up the island’s public transport, and develop a zero-waste system, becoming the world’s first zero-waste island.”
EV owners on Tilos can charge their vehicles for free. This is a policy adopted by the local council aiming to promote EV ownership, although Tilos’ residents have been hesitant to switch due to the high cost of the technology. Nevertheless, added Kamma, “Tilos will continue to offer free EV charging for the time being.”
The island’s success has been striking. By contrast, Agios Efstratios, a Greek island that had followed the CRES open call in 2012, was only able to install its energy system in 2024 and is currently still in a testing phase.
Kamma said Tilos was the inspiration for the Gr-Eco Islands Initiative. Now, she said, the Greek government needs to assign budgets and technical assistance to the islands, and let them decide the projects they want to implement.
Which islands will participate in the government initiative is an open question. The Ypen spokesperson said that the law envisages all Greek islands will go green. However, he added that to make better use of available funds, the government has used a range of criteria to select 39 islands with populations of 100 to 3,500 inhabitants. These include population size, energy demand profile, whether an isle is expected to link to the mainland grid soon, the local economy, and other factors. Not everyone thinks the government’s criteria are clear and straightforward. Eunice told pv magazine that “the selection of islands listed in the initiative does not follow a transparent and consistent process.”
The developer also said the Gr-Eco initiative “applies different business models and technological solutions per island, lacking an overall strategy.” Eunice would like to see a more cohesive approach that also promotes hybrid and standalone energy systems, including energy storage. The company is not against energy communities, either, and has asked for wider regulatory support toward the establishment of such entities. Eunice’s main argument is that private investors should not be excluded from Gr-Eco island business models. Often, it is the private investors who bring technology innovation and sources of finance, the company argues.
Ypen’s and Eunice’s ideas do not differ substantially. The Ypen spokesperson said that, where possible, the Gr-Eco initiative should blend state and private finance. He said tendering hybrid systems for remote isles that do not link to Greece’s mainland is a solution and that private investors should also be able to bid for such tenders.
Equally, he added, Ypen promotes the model of island energy communities based on self-consumption, so that citizens and local councils can participate actively in the energy transition.
Such statements show that the Gr-Eco initiative is still taking shape. Any uncertainty regarding its application is exacerbated by the fact that there is no single government department responsible for the program, which is administered by a number of offices and ministries that often have very different ideas and interests.
It appears that, seven years after the Tilos microgrid project was commissioned, and three years after the introduction of the Gr-Eco Islands Initiative, the island is still leading the way. The government, the European Union, island councils, and private investors should rethink why that is still the case.
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