METLEN assembles battery storage portfolio spanning Britain, Italy and Greece

A Greek industrial group that most Europeans would struggle to name is quietly assembling one of the continent's broader battery storage portfolios. METLEN, which operates through its M RESET energy division, now has projects running or under construction across three countries, deploying distinctly different commercial models in each market.

The combined capacity tells part of the story. In Britain alone, METLEN has delivered or is building roughly 30 battery and hybrid solar-storage units totalling nearly 2 GWh. In Italy, a 25 MW plant is already feeding power under a tolling contract. In Greece, a 330 MW standalone battery, one of the largest of its kind in Europe, has begun feeding into the national grid. The geography matters because each country presents a different regulatory and financial environment, and METLEN's approach shifts accordingly.

The UK: a volume play with grid-connection work attached

METLEN's most recent British contract is a balance-of-plant agreement with Pulse Clean Energy for the Penn BESS project in the West Midlands. At 129 MW with 362 MWh of installed battery capacity, it is the largest storage project METLEN has taken on in the country measured by the amount of energy the batteries can hold. The scope extends beyond the battery units themselves to include grid-connection works, a part of the development process that has become a bottleneck across British storage projects. Energisation is expected before the end of 2027.

Pulse Clean Energy, the developer, is a relatively young company but already operates one of Britain's larger battery fleets, at 400 MWh, with another 400 MWh under construction. It has set a target of reaching 2 GWh by 2030. The Penn project would represent a significant step towards that goal, and METLEN's involvement in grid-connection infrastructure suggests Pulse wants a contractor that can handle the full delivery chain rather than simply supplying equipment.

Britain's storage market has attracted more developers than most European countries, partly because wholesale price volatility and ancillary service contracts create revenue opportunities. The queue for grid connections, however, has become a serious constraint. National Grid's Electricity System Operator has reported connection wait times stretching well beyond a decade for some projects, though recent reforms aim to thin the queue by removing speculative applications. METLEN's decision to take on grid-connection work directly signals that it sees this as a competitive advantage rather than a problem to offload.

Italy: tolling agreements and project finance

The Italian story is different. METLEN has completed a 25 MW/75 MWh battery plant in Apulia, in the province of Brindisi, and secured €18 million in long-term financing for the asset. What makes the deal notable is the commercial structure. The plant operates under a seven-year physical tolling agreement with Dolomiti Energia Group, a utility based in the Trentino region. Under tolling arrangements, the battery owner charges and discharges the system on behalf of a counterparty that pays a fee for the service, rather than trading the electricity itself. This shifts market risk from the asset owner to the tolling party.

Such structures are common in US and British storage markets but remain relatively unusual in Italy. The financing package, described as among the first of its kind in the Italian storage sector, suggests that lenders are becoming comfortable with tolling-based revenue models in a market that has historically relied on capacity payments and grid-service contracts. For METLEN, the arrangement provides predictable income while limiting exposure to Italian wholesale price swings. For Dolomiti Energia, it gives access to flexible capacity without committing capital to build its own plant.

Italy's storage market is smaller than Britain's but growing. The national grid operator, Terna, has been running capacity auctions and long-term procurement processes for storage and demand-response resources. The regulatory framework is still taking shape, which makes the tolling model attractive: it provides revenue certainty without depending on policy mechanisms that could change.

Greece: recovery funds and record-scale batteries

The Greek projects illustrate yet another path. METLEN's partnership with Karatzis Group of Companies has produced a standalone battery in Thessaly with a capacity of 330 MW and installed battery capacity of 790 MWh. That scale puts it among the largest standalone battery projects planned in Europe, and its output has already been integrated into Greece's electricity transmission system. The milestone matters because grid integration is often the slowest phase of a storage project, requiring technical studies and regulatory sign-offs that can delay energisation by months.

A second Greek project, the 48 MW/96 MWh Aenaos battery in Polygyros, Halkidiki, in Central Macedonia, has been completed under Greece's National Recovery and Resilience Plan, known as Greece 2.0. This programme channels EU NextGenerationEU funding into national investment priorities, including clean energy infrastructure. The involvement of EU recovery money distinguishes the Aenaos project from METLEN's other storage investments, which rely on private capital and commercial contracts. Recovery funds can cover a portion of capital costs, reducing the project's exposure to merchant risk, but they come with conditions on procurement, reporting and timelines that private deals do not impose.

What the commercial models reveal about each market

Taken together, the three countries show how storage developers must adapt to local conditions. In Britain, a competitive merchant market with volatile prices rewards operators who can respond quickly, but the sheer volume of projects means developers want contractors who can manage the entire build, including the grid connection. In Italy, where policy frameworks are still evolving, tolling agreements provide a halfway house between full merchant exposure and regulated contracts. In Greece, EU recovery funding offers capital support that would otherwise be hard to obtain in a smaller market with limited domestic project-finance expertise.

METLEN's strategy across these markets has been to avoid a single template. The company has partnered with local developers, taken on different scopes of work, and accepted different risk profiles depending on what each market can support. That flexibility is partly a necessity. No European country has yet settled on a permanent regulatory framework for storage, and the revenue stack, the combination of wholesale trading, frequency response, capacity payments and tolling fees, varies significantly across borders.

Scale and competition in European storage

METLEN is not alone in building cross-border storage portfolios. Larger energy groups, including Engie, Shell and Statkraft, have been acquiring and developing battery assets across the continent. The difference is that METLEN, which grew out of Greek metallurgy and energy generation, has positioned itself as a delivery partner as much as an asset owner. The balance-of-plant contract in Britain and the tolling arrangement in Italy both cast the company in a service-provider role, building and operating projects that other parties own or offtake from.

The total European pipeline for battery storage has grown sharply. According to the International Energy Agency, installed storage capacity in the European Union reached roughly 20 GWh at the end of 2025, with much of the growth concentrated in Britain, Germany and Italy. IEA projections suggest that figure could exceed 100 GWh by 2030 if permitting and grid-connection bottlenecks ease. METLEN's portfolio of roughly 2 GWh in Britain, plus the Italian and Greek projects, gives it a meaningful but not dominant share of that pipeline.

Questions of profitability and oversupply

The rapid build-out of storage capacity raises its own risks. In Britain, the number of projects seeking connection has far outstripped what the grid can absorb in the near term. If too many batteries enter the market simultaneously, the ancillary-service revenues that underpin many business cases could fall, squeezing margins for all operators. The same dynamic has already played out in frequency-response markets, where prices dropped as capacity flooded in faster than demand grew.

In Greece, the Thessaly project's scale, 330 MW against a national peak demand that fluctuates around 10 GW, means its output will be significant relative to the system. How it is dispatched, and whether it can earn sufficient revenue from arbitrage and grid services, will be watched closely by other developers considering similarly large projects in smaller European markets.

The Italian tolling model sidesteps some of these concerns by locking in a fixed fee, but it also limits upside. If wholesale spreads widen, the tolling party captures the gain, not the asset owner. METLEN and its financiers have judged that predictable income outweighs the option to trade, at least for the next seven years.