DNV, the independent energy expert and assurance provider, has acted as a technical advisor on the financing of a USD 55.63 million portfolio of three standalone battery energy storage systems being developed by Return Energy in the Spanish province of Bizkaia.

The portfolio is, to date, the largest standalone battery storage portfolio in Spain to reach financial close.

Three Projects, 55 MW and 220 MWh

The three projects are located in Güeñes, Barakaldo, and Lezama. Together, they will provide a combined power capacity of 55 MW and a storage capacity of 220 MWh. Return Energy, an independent energy storage provider and infrastructure developer, is developing the systems.

The projects form part of Return Energy's wider pipeline in the Basque Country, which exceeds 1400 MWh of energy storage capacity and 352.6 MW of power capacity.

DNV's Role in the Technical Due Diligence

DNV served as technical advisor during a technical due diligence process for the financing. In that role, the company provided an independent assessment of the project design, technology selection, contracts, and key technical risks. It also supplied recommendations to mitigate those risks and support the financing process.

Brice Le Gallo, Vice-President and Regional Director for Southern Europe, MEA, and LATAM, Energy Systems at DNV, described the company's contribution in terms of investor confidence.

"Our role is to provide an independent view of the technology, design, and technical risks so that the parties involved can make investment decisions with greater confidence," he said.

He added that projects reaching financial close are an important part of moving energy storage development from planning into deployment.

Storage Needs in a Renewables-Based System

The announcement places the Bizkaia portfolio in the context of Spain's changing electricity system, which is expected to require substantial growth in energy storage capacity as the share of variable renewable generation increases.

Battery energy storage systems can help balance differences between electricity production and demand, support grid stability, and provide additional flexibility to the power system.

Le Gallo pointed to DNV's Energy Transition Outlook for Spain, which shows that a more electrified, renewables-based energy system will require substantially more storage to provide flexibility and support grid stability.

"Energy storage is becoming an increasingly important part of Spain's power system as renewable generation grows," he said.

A New Asset Class for Spain

Steve Sceery, Country Head for Return Energy in Spain, said DNV had been a key partner in completing the financing for what he called a landmark transaction in Spain.

He noted that the company brought its full technical expertise to what is a new asset class in the country, which he said was instrumental in ensuring a swift and successful transaction. "We valued both their knowledge and agility in this process," Sceery said.

Carlos Albero, Market Manager for Iberia at DNV, said the company combines experience from established battery storage markets, including the US, the UK, the Nordics, and Chile, with its local energy expertise in Spain.

He said the work on the Bizkaia portfolio reflects the growing role of independent technical assessment as standalone storage moves from an emerging segment towards wider deployment in the Spanish market.

National Targets and the Path to Scale

Spain's National Energy and Climate Plan foresees a substantial expansion of storage capacity by 2030, targeting 22.5 GW, of which 12.5 GW is related to BESS. Deployment remains at an early stage.

According to the announcement, projects now reaching financing and construction will help determine how quickly storage can scale alongside renewable generation.

The Bizkaia portfolio's financial close, supported by an independent technical review covering design, technology selection, and contractual and technical risks, offers an early example of how standalone storage projects in Spain are being brought through the financing process.

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