Greece has opened a stand-alone battery energy storage system (BESS) in Larissa, Thessaly, following a joint investment by METLEN and the Karatzis Group of Companies.
The facility has a power capacity of 330MW and an energy storage capability of 790MW-hours (MWh).
The inauguration event was attended by senior government officials including Prime Minister Kyriakos Mitsotakis and Minister of Environment and Energy Stavros Papastavrou.
Members of the Greek Parliament, regulatory representatives and local authorities were also present.
METLEN and the Karatzis Group developed the project through a joint investment vehicle. The Karatzis Group holds a 51% interest while METLEN retains a 49% stake.
METLEN took responsibility for the construction, operational management and maintenance, leveraging its experience in energy storage infrastructure.
The project is expected to enhance the flexibility and resilience of Greece's electricity grid, supporting the integration of renewable energy sources.
According to the companies, the facility is seen as an important piece of infrastructure for both the national and wider European energy market.
Mitsotakis addressed the ceremony, stating that the new facility is “an important step towards building the Greece of the future”.
He emphasised its role in strengthening national energy security and competitiveness, and extended congratulations to METLEN and the Karatzis Group for completing the project.
METLEN executive chairman Evangelos Mytilineos said: “I am particularly proud that today, here in Thessaly, we are inaugurating Greece’s largest stand-alone energy storage facility in eastern Europe and one of the largest across the European Union.
“This project reflects the new reality of the energy system, as storage, alongside grids and interconnections, is essential if we are to use the clean energy we generate with efficiency and provide businesses and consumers with a more reliable and predictable energy supply.”
The investment received loan support from the EU’s Recovery and Resilience Facility – NextGenerationEU.
The partnership between METLEN and the Karatzis Group was highlighted as a key factor in the timely and effective delivery of the project.
In March 2026, the PPC Group and METLEN formed a joint venture to develop BESS projects totalling up to 1.5GW and 3GW-hours across Romania, Bulgaria and Italy.
