Return reached financial closure and began construction of its first battery storage portfolio in Spain , consisting of three independent projects in Güeñes, Baracaldo and Lezama , in Vizcaya, totaling 55 MW / 220 MWh .
According to the company, this is the largest independent BESS portfolio in Spain to secure bank financing and enter construction to date , a step that takes these assets from development to an effective execution phase.
The financial structure includes €50 million provided by Rabobank for construction and other credit guarantees , while ENGIE supports the revenue model through a 10-year tolling agreement signed with Return.
The scheme is completed with CATL as the supplier of battery technology and long-term maintenance services, while Enerland will be in charge of the execution of the three projects on the ground.
The portfolio will last approximately four hours: it will be able to deliver 55 MW of power simultaneously for about four hours , until reaching 220 MWh of available energy capacity before requiring recharging.
Commercial operation is scheduled to begin in the second half of 2027 .
“This milestone demonstrates that battery storage in Spain has become an infrastructure ripe for investment,” said Steve Sceery, director of Return Spain.
The executive highlighted that the company managed to bring together “the long-term revenue model, financing, technology and execution capabilities necessary to take these projects to the construction phase.”
The key element in unlocking the financing was the tolling agreement with ENGIE, previously announced by the companies. Under this model, Return retains ownership and operation of the assets, while ENGIE manages the battery market share in the various Spanish energy markets.
This structure provides long-term revenue visibility , one of the main challenges currently facing the development of independent BESS in Spain.
“Battery storage is becoming a fundamental element of modern electrical systems,” said Jean-Nicolas Lejeune, Managing Director of Supply and Energy Management activities at ENGIE Iberia.
“Our agreement with Return provides this portfolio with the revenue visibility it needed to reach financial close,” he added.
From Rabobank, Carol Kort, executive director of Project Finance, defined the operation as "an important milestone for the Spanish energy market", at a time when storage is beginning to gain weight within the financing of new energy infrastructure.
During the construction phase, the three projects are expected to generate around 50 full-time local jobs in the Bilbao area .
From pipeline to construction: the next challenge for Spanish storage
The portfolio comes at a time when the rapid growth of renewable generation increases the need for flexibility within the Spanish electricity system.
BESS systems allow electricity to be absorbed during periods of high solar and wind production and then returned later when demand increases or renewable generation decreases.
They can also reduce spills, provide balancing services and strengthen grid stability, an aspect that gained greater prominence after the recent disruptions recorded in the Spanish electricity system.
Return's three assets will be connected around Bilbao and will seek to provide precisely that flexibility capacity to a region that will have to integrate increasing volumes of renewable generation.
For the company, the financial closing also represents the leap from development to construction in one of its priority markets in Europe.
Return will retain ownership and operation of the projects in the long term, applying an integrated model that encompasses development, business structuring, financing, construction and subsequent asset management.
The operation also sends a signal to the Spanish market: independent storage is beginning to find structures capable of combining bank debt, long-term contracts and technology providers to move towards construction .
With 55 MW / 220 MWh already under construction and scheduled for operation in 2027, the Vizcaya portfolio thus becomes one of the first large-scale cases seeking to demonstrate the bankability of independent BESS in Spain.