IN Brief:
- Four current METLEN project milestones across Britain, Italy, and Greece total 532MW/1,323MWh.
- Penn combines 129MW/362MWh with grid works, while the 25MW/75MWh Brindisi battery has long-term finance and a seven-year tolling agreement.
- Greek projects include a 330MW/790MWh Thessaly system moving through transmission integration and the completed 48MW/96MWh Aenaos BESS.
METLEN is advancing battery projects totalling 532MW/1,323MWh across Britain, Italy, and Greece, combining grid-delivery work, project finance, tolling, transmission integration, and completed assets within one European portfolio.
In Britain, the company has signed a balance-of-plant contract with Pulse Clean Energy for the 129MW/362MWh Penn BESS in the West Midlands. METLEN’s scope includes grid connection works, with energisation expected by the end of 2027.
The project is its largest UK battery scheme by energy capacity. METLEN says it has delivered or is working on around 30 UK battery units, including hybrid and co-located solar-storage installations, representing almost 2GWh.
Pulse Clean Energy operates a battery fleet of about 400MWh, has another 400MWh under construction, and has stated an ambition to reach 2GWh by 2030. Penn therefore forms part of a broader owner-operator programme rather than a single isolated EPC award.
Different markets are producing different contracts
The Italian milestone follows another route. METLEN has secured €18 million of long-term financing for a 25MW/75MWh battery in the province of Brindisi, which became operational during 2026 and is backed by a seven-year physical tolling agreement with Dolomiti Energia Group.
A tolling agreement gives the asset a more defined commercial relationship than pure merchant operation, but it also increases the importance of technical availability. The battery still has to meet agreed power and energy obligations while staying within cell, inverter, thermal, and warranty limits.
State of charge becomes part of the contract-management problem. A three-hour system cannot discharge indefinitely, so operating strategy has to balance market opportunities with the need to retain sufficient energy for later commitments and maintenance windows.
Italy is also developing storage through national procurement. Terna’s second MACSE auction is due in November and targets 16GWh for 2029 delivery, creating another route to long-term contracted revenues. METLEN’s Brindisi project shows that privately negotiated tolling can sit alongside that state-backed mechanism.
The Greek projects are different again. METLEN and Karatzis Group have developed a 330MW/790MWh standalone battery in Thessaly, where transmission integration is now a central delivery milestone before full operation and provision of grid services.
A second Greek scheme, the 48MW/96MWh Aenaos BESS at Polygyros in Halkidiki, has been completed under Greece’s Recovery and Resilience Plan. The two projects therefore combine different durations, project sizes, and funding routes within the same national market.
The common constraint is grid integration
Although the commercial structures vary, all four projects depend on the electrical infrastructure between the battery containers and the power system. Transformers, switchgear, cabling, protection, metering, communications, and supervisory controls determine whether the stored energy can be charged, exported, and dispatched reliably.
At Penn, grid connection is explicitly part of METLEN’s balance-of-plant scope. In Thessaly, transmission integration is itself the latest milestone. Those details are more consequential than the battery-container count because a completed storage block has limited value until its network interface has been tested and accepted.
European storage markets are therefore becoming less uniform rather than more. Battery hardware can be repeated across projects, but connection standards, market rules, contracted services, permitting, and revenue structures differ substantially between Britain, Italy, and Greece.
That places a growing burden on controls and protection engineering. The same battery technology may have to satisfy different requirements around frequency response, reactive power, fault behaviour, metering, dispatch, and remote control in each national system.
Scale compounds the delivery problem. The four named milestones alone represent more than 1.3GWh, while METLEN reports larger pipelines in both Britain and Italy. Procurement consequently has to coordinate battery systems with high-voltage equipment, civil works, connection dates, factory tests, commissioning resources, and software integration across multiple sites.
Programme management becomes as important as component selection. A delayed transformer, incomplete substation, or unavailable commissioning team can postpone revenue even where the battery modules themselves are already on site.
The current portfolio also shows how storage finance is maturing. Some assets are financed after construction, others rely on tolling contracts, and larger projects are still clearing transmission and commissioning milestones. The technology is increasingly familiar; the difficult part is assembling grid access, engineering delivery, and a revenue structure that remains credible over the life of the project.
METLEN’s 532MW/1,323MWh of current milestones therefore offers a useful cross-section of European battery deployment. The next test is operational rather than promotional: whether projects delivered through several different commercial models can achieve the availability, dispatch performance, and grid compliance assumed when their finance and contracts were agreed.
