275 MW of energy storage ‘frozen’ in Crete, the Cyclades and the Ionian Islands

Energy storage projects with a combined capacity of 275 MW on three island regions of the country remain “frozen”, according to a report by Cyclades24. The capacity distribution concerns 200 MW in Crete, 50 MW in the Ionian Islands and 25 MW in the Cyclades, namely projects affecting exclusively non-interconnected islands, where energy storage is considered critical for network stability and the integration of renewable sources.

According to the report, the cause of the stagnation is found in a modification of the tender terms in September 2025, with which a guarantee requirement of 200,000 euros per MW was imposed. The report does not name the body that carried out this modification, nor does it clarify the reasoning that led to the change in terms. As a result of the development, according to Cyclades24, guarantee letters with a total value of approximately 100 million euros remain “locked up”, without the investments proceeding.

The matter affects three regions with different but convergent energy characteristics. Crete, as the largest non-interconnected island power system in the country, accounts for the largest part of the “frozen” capacity, with 200 of the 275 MW. The Ionian Islands and the Cyclades, with smaller but equally fossil-fuel-dependent energy systems, share the remaining 75 MW, with 50 MW in the Ionian and 25 MW in the Cyclades. The report does not name the companies that have submitted the guarantee letters, nor does it specify how many separate projects correspond to the 275 MW in total. Energy storage projects, such as battery systems, are considered crucial for non-interconnected island systems, as they enable the utilization of electricity generated from renewable sources at times when demand is lower than production, while reducing reliance on oil-fired power plants on these islands.

For developments on the matter, Cyclades24 does not foresee a specific timeline for resolution, while it is not stated whether an official response or revision of the tender terms from the competent body is pending. As long as the situation remains as it is, the approximately 100 million euros in guarantee letters continue to be tied up in investments that are not proceeding, while the energy storage projects on the three island systems, which could potentially contribute to stabilizing electricity costs on non-interconnected islands, as documented in recent reports on wholesale electricity prices, remain pending. Cyclades24 does not clarify whether the investors have resorted to legal action against the modification of the terms or whether a dialogue is pending in some other way between the parties involved for resolution of the matter in the near future.