A roundup of large-scale European BESS project news, with Principia completing a project in Greece, Repono buying one in Romania, Kyon choosing optimisers for two in Germany and Voltalia and NGEN targeting Portugal.
Principia completes BESS in Greece
Independent power producer (IPP) Principia has completed construction on its first battery energy storage system (BESS) project in Greece.
The 49MW/127.04MWh Themelio BESS in Chalkidiki started construction in April 2025 and will enter full commercial operations in December 2025, after just six months of construction, Principia said.
The firm is a joint venture between Enel Green Power Hellas (part of the international utility and IPP Enel) and investor Macquarie Asset Management, which was rebranded to Principia Energy after Macquarie took a 50% stake in 2024.
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The project uses BESS technology from China-based Sungrow, comprised of 26 units of 5.015kWh each using 314Ah cells from manufacturer CALB. Sungrow also provided the inverters.
Themelio will help reduce curtailments on renewables because of system constraints and also smooth out peak demand pricing periods.
Principia didn’t say if the project was any of the 12 totalling c.400MW that won long-term capex support in the first auction round of an EU-backed scheme in 2023. A second auction took place awarding 300MW in early 2024 while a third scheduled for late 2024 was cancelled due to confusion over the entry requirements.
Utility Public Power Corporation (PPC) started building two BESS projects that have won support, totalling 98MW/196MWh of capacity, earlier this year.
EU-backed platform Repono buys first major project, in Romania
In Romania, Sweden-headquartered BESS platform Repono AB has acquired a 202MW/404MWh standalone BESS project in Argeș County from a local renewables developer, part of a long-term commitment to deploy up to 1.4GW in the country.
The project is ready-to-build (RTB) and has a grid connection with TSO Transelectrica at the 220kV Pitești substation
Commodities trader Gunvor and optimiser Enspired will manage the project’s commercialisation and route-to-market (RTM).
Repono was launched by EU body EIT InnoEnergy, along with other investors and stakeholders, in mid-2024, targeting a staggering 100GWh of deployments by 2030. It partnered with Chinese system integrator Hyperstrong a short while later with a 1.4GWh supply deal.
“This transaction represents an important milestone for Repono AB and demonstrates our continued commitment to developing large-scale storage infrastructure that supports Europe’s energy transition,” said Karim Nils Grueber, CEO of Repono AB.
Kyon chooses Entrix and Enspired for Germany BESS
Entrix has also secured a possible deal in Germany, with developer-operator Kyon Energy entering into a strategic framework agreement for it and peer Enspired to optimise its upcoming BESS projects in the country.
Kyon didn’t say how much capacity, or how many projects, each optimiser would take.
“Each optimiser will get their own BESS projects to market across all available streams in order to maximise their revenues,” Kyon said, with the first set to come online next year.
“The cooperation with Entrix and Enspired has grown over the years and is now culminating in the marketing of our assets,” said Benedikt Deuchert, head of business development & regulatory affairs at Kyon Energy.
Kyon was acquired by oil and gas major TotalEnergies in January 2024, which announced it was launching construction on a 321MW portfolio in Germany developed by Kyon earlier this year, though it isn’t clear if this is the same portfolio that Entrix and Enspired will be optimising.
Voltalia subsidiary and NGEN investing in Portugal BESS
IPP Voltalia subsidiary Helexia and BESS platform NGEN Group have signed an agreement to implement BESS projects in Portugal with an investment of €20 million (US$23.2 million) in 2026, according to local outlets.
The agreement covers the development of a pipeline of more than 100MW, and Helexia expects to complete around a quarter of that in 2026, which is what the €20 million will cover.
The projects will be primarily behind-the-meter (BTM) allowing companies to reduce costs and increase energy independence and resiliency, including via integration with solar PV.
BTM applications would typically be used in the commercial & industrial (C&I) market segment, which may have seen increased interest in Iberia following the prolonged blackout there in Spring 2025. In September, manufacturer Turbo Energy announced a 336MWh C&I battery storage order in Spain.
