Battery Storage Plant Inaugurated in Larissa as Greece's Largest Standalone BESS

Prime Minister Kyriakos Mitsotakis attended the inauguration of Greece's largest standalone battery energy storage system in Larissa, Thessaly on 14 October 2026, a 330 MW facility with 790 MWh of storage capacity built by METLEN and Karatzis Group of Companies.

The plant, which the companies describe as the largest standalone energy storage facility in Eastern Europe and one of the largest in the European Union, was delivered through a joint investment vehicle in which Karatzis Group holds 51% and METLEN 49%.

A High-Level Ceremony in Thessaly

The inauguration brought together the Greek Prime Minister, Minister of Environment and Energy Stavros Papastavrou, representatives of the Greek Parliament, regulatory and productive bodies, and local authorities.

In his address, Mitsotakis described the facility as an important step towards building the Greece of the future, highlighting its contribution to the country's energy security and competitiveness and congratulating the two partner companies on completing the project. The companies frame the plant as an energy infrastructure project of strategic importance.

According to Company, storage, grid works and interconnections are essential preconditions for attracting investment and strengthening the production base of both Greece and Europe.

The facility is intended to enhance the flexibility and resilience of the energy system and to support more efficient use of renewable energy generation.

What the Partners Say

Evangelos Mytilineos, Executive Chairman of METLEN, said he was particularly proud that the largest standalone energy storage facility in Eastern Europe, and one of the largest in the EU, was being inaugurated in Thessaly.

The project, he stated, reflects the new reality of the energy system, in which storage alongside grids and interconnections is essential to use clean energy efficiently and to provide businesses and consumers with a more reliable and predictable energy supply. He thanked the partners at Karatzis Group, Antonis Karatzis personally, and everyone at METLEN who contributed to delivery.

Antonis Karatzis, Chairman and CEO of Karatzis Group, called the inauguration an important milestone for his group and for the country's energy future. He said the group's participation in a storage project of this scale reflects a strategic choice to invest in infrastructure with a long-term horizon and meaningful value for the Greek economy.

In his view, the partnership with METLEN shows how two leading Greek companies can combine strengths, expertise and willingness to invest to deliver projects to international standards, increase the use of renewable energy, strengthen grid stability and enhance Greece's energy security. He added that the project marks the beginning of a new era in which Karatzis Group intends to play an active and meaningful role.

METLEN's Role in Delivery

METLEN undertook the construction, operation and maintenance of the facility, drawing on its international experience in complex energy storage projects.

The companies note that the successful delivery and commissioning of a project of this scale demonstrates their technical expertise and ability to turn complex investment plans into operational infrastructure that will support the country's growth prospects for decades to come. The Thessaly plant is presented as a flagship project for the new energy era and an important step towards building the productive capacity that will underpin the next chapter of Greece's economic growth.

The companies also point to the project as evidence of the importance of mature projects, modern infrastructure, and companies with the scale and expertise to turn investment plans into operational assets.