Return Energy Secures $55.63 Million Financing for 55 MW Battery Storage Portfolio in Bizkaia, Spain, With DNV as Technical Advisor

A USD 55.63 million financing package has been completed for a three-project standalone battery energy storage portfolio in the Spanish province of Bizkaia, with DNV acting as technical advisor on the deal.

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

Where the Projects Stand

The three systems are situated in the municipalities of Güeñes, Barakaldo, and Lezama.

Combined, they will deliver 55 MW of power capacity and 220 MWh of storage capacity. Return Energy, an independent energy storage provider and infrastructure developer, is behind the development.

The portfolio sits within a wider Basque Country pipeline for Return Energy that totals more than 1400 MWh of energy storage capacity and 352.6 MW of power capacity.

How the Due Diligence Was Structured

During the financing process, DNV carried out technical due diligence, delivering an independent assessment covering project design, technology selection, contracts, and key technical risks.

The company also issued recommendations aimed at mitigating those risks and supporting the financing. Brice Le Gallo, Vice-President and Regional Director for Southern Europe, MEA, and LATAM, Energy Systems at DNV, framed the work around 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 financial close represents an important step in taking storage development from planning into actual deployment.

Why Storage Matters for Spain's Grid

According to the announcement, Spain's electricity system is expected to need substantial growth in storage capacity as variable renewable generation expands. Battery energy storage systems can balance gaps between production and demand, support grid stability, and add flexibility to the power system.

Le Gallo referenced DNV's Energy Transition Outlook for Spain, which indicates that a more electrified, renewables-based system will require significantly more storage for flexibility and grid stability. "Energy storage is becoming an increasingly important part of Spain's power system as renewable generation grows," he said.

The Developer's View on a New Asset Class

Steve Sceery, Country Head for Return Energy in Spain, described the financing as a landmark transaction for the country and credited DNV as a key partner in completing it.

He said the advisor brought its full technical expertise to what constitutes a new asset class in Spain, which he called 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, noted that the company pairs experience from established battery storage markets, including the US, the UK, the Nordics, and Chile, with local energy expertise in Spain.

In his view, the Bizkaia work reflects the growing importance of independent technical assessment as standalone storage shifts from an emerging segment toward broader deployment in the Spanish market.

National Targets Frame the Market

Spain's National Energy and Climate Plan projects a substantial expansion of storage by 2030, with a target of 22.5 GW, of which 12.5 GW relates to battery energy storage systems.

Deployment is still at an early stage, and the announcement states that projects now reaching financing and construction will shape how quickly storage can scale alongside renewable generation.

With its financial close backed by an independent technical review of design, technology selection, and contractual and technical risks, the Bizkaia portfolio stands as an early example of how standalone storage projects in Spain are moving through the financing process.