A landmark energy infrastructure project strengthening security of supply and Greece’s productive capacity
On Wednesday, 14 October 2026, Karatzis Group of Companies and METLEN inaugurated Greece’s largest standalone Battery Energy Storage System (BESS) in Larissa, Thessaly. With a power capacity of 330 MW and a storage capacity of 790 MWh, the facility is also one of the largest installations of its kind in Europe.
The project was delivered as part of the strategic partnership between Karatzis Group and METLEN through a joint investment vehicle in which the two companies hold stakes of 51% and 49%, respectively.
The inauguration ceremony was attended by Prime Minister Kyriakos Mitsotakis, Minister of Environment and Energy Stavros Papastavrou, and representatives of Parliament, regulatory and industry bodies, and local government.
The new BESS facility in Thessaly is a strategically important energy infrastructure project. Energy storage, electricity networks and interconnections are essential for attracting investment and strengthening the productive capacity of Greece and Europe. The project demonstrates the importance of well-developed investments, modern infrastructure and companies with the scale and know-how not only to commit capital, but also to deliver complex projects.
It is a benchmark for the new energy era and an important step towards building the industrial and economic capacity that will support Greece’s future growth. METLEN undertook the construction, operation and maintenance of the facility, drawing on its international expertise in demanding energy-storage developments.
Speaking at the inauguration, Prime Minister Kyriakos Mitsotakis described the facility as an important step towards Greece’s future. He highlighted how the investment contributes to the country’s energy security and competitiveness and congratulated METLEN and Karatzis Group on the project.
Antonis Karatzis, Chairman and Chief Executive Officer of Karatzis Group of Companies, stated:
“Today marks an important milestone for Karatzis Group and for the energy future of our country. Our participation in an energy-storage project of this scale confirms our strategic decision to invest in infrastructure with a long-term outlook and meaningful value for the Greek economy.”
“Together with METLEN, we are demonstrating that two leading Greek companies can combine their strengths, expertise and commitment to investment to deliver projects built to international standards. These projects support the greater use of renewable energy, the stability of the electricity system and Greece’s energy security. For us, this project marks the beginning of a new era in which we intend to play an active and meaningful role.”
Evangelos Mytilineos, Executive Chairman of METLEN, commented:
“I am especially proud that today, here in Thessaly, we are inaugurating the largest standalone energy-storage facility in Eastern Europe and one of the largest in the European Union.”
“This project reflects the new reality of the energy system: storage, together with networks and interconnections, is essential if we are to make efficient use of the clean energy we produce and secure a more reliable and predictable electricity supply for businesses and society.”
“I would like to warmly thank our partners at Karatzis Group, Antonis Karatzis personally, and everyone at METLEN who contributed to the delivery of this landmark project.”
Successfully completing and commissioning a standalone energy-storage project of this scale highlights the partners’ technical expertise and delivery capabilities. It shows how complex investment plans can be transformed into operating infrastructure that will underpin Greece’s development for decades to come.
The investment is being implemented with loan support from the European Union Recovery and Resilience Facility – NextGenerationEU.
About Karatzis Group of Companies
Founded in Heraklion, Crete, in 1973 by the late Miltiadis Karatzis, Karatzis Group of Companies has grown under the leadership of Antonis Karatzis, Chairman and CEO, into an internationally active Greek business group operating in industry, energy, hospitality and general aviation.
The Group has a commercial presence in 72 countries, employs thousands of people and operates five production facilities in Greece and Germany. It holds a strong position in the global markets for industrial netting and specialised packaging products.
Karatzis Group has been active in the energy sector since 2007, investing in solar and wind power projects and subsequently expanding into electricity storage. Its publicly announced investment portfolio includes approximately 1 GW of renewable energy projects under development and 430 MW of energy storage projects.
The strategic partnership with METLEN to develop Greece’s largest standalone battery energy storage facility, with Karatzis Group holding a majority stake of 51% in the joint investment company, is a major step in the expansion of the Group’s energy activities.
In hospitality, the Group develops its Nana Hotels portfolio in Crete, including the five-star Nana Golden Beach, Nana Princess Resort & Spa and Nana Royal. The Group is also active in general aviation through Panellenic Airlines.
The Group’s industrial and investment activities are supported by five industrial plants in Greece and Germany, specialising in packaging nets, shading nets and multilayer silage films. Its energy portfolio combines renewable generation with electricity storage infrastructure. Its 51% participation in the €170 million Thessaly BESS investment, with a capacity of 330 MW / 790 MWh, extends its activities beyond renewable power generation into storage and greater flexibility for the electricity system.
About METLEN
METLEN Energy & Metals Plc is an international industrial and energy company with a leading position in the metals and energy sectors, focused on sustainable development and the circular economy. METLEN is a benchmark in competitive green metallurgy in Europe and worldwide, and operates the European Union’s only fully integrated bauxite, alumina and primary aluminium production facility, with its own port infrastructure.
In its Energy Sector, METLEN offers integrated energy solutions across thermal and renewable power generation, electricity distribution and trading, as well as investments in grid infrastructure, battery storage and other green technologies. The company operates in markets across five continents, in more than 40 countries, employs over 8,500 people and follows a collaborative operating model across its business sectors.
METLEN Financial Information
METLEN is primarily listed on the London Stock Exchange and secondarily listed on the Athens Stock Exchange, and is a constituent of the FTSE 100. In 2025, the company reported consolidated revenue of €7.11 billion, EBITDA of €753 million and net profit of €314 million. Adjusted net debt amounted to €2.10 billion, with a net-debt-to-EBITDA ratio of 3.1x, maintaining a strong financial position.
METLEN receives ESG assessments from leading international organisations. It is the only Greek company included in the Dow Jones Best-in-Class Emerging Markets Index and has been recognised by MSCI, Sustainalytics, ISS QualityScore, ISS Corporate Score, S&P Global ESG, LSEG, CDP, FTSE Russell, ESG Book, EcoVadis, Bloomberg and IdealRatings.