Building Europe's battery storage network
The future of battery storage lies in interconnected networks. Return Energy is building a Pan-European platform to prove that thesis at scale. By Nick Herbert.
With fresh backing from Dutch pension giant APG and an ambitious target to deploy 5GW across four European markets by 2030, Amsterdam-based Return Energy is positioning itself as a Pan-European storage platform built on a dual-engine strategy of acquisition and organic growth.
Managing director Sjoerd Bazen joined the company in October 2024 after decades in gas, chemicals, and oil storage, bringing an infrastructure operations mindset to a market still in its relative infancy. The attraction was simple: the growing importance of storing electrons as European energy markets become more volatile due to the rise of solar and wind generation. Battery storage technology had caught up with wind and solar and Return was ramping up growth in the BESS environment.
Return builds and operates large-scale energy storage systems and offers them as a service across the Netherlands, Belgium, Germany and Spain. Its infrastructure enables customers to access its network of large-scale energy storage solutions without owning the assets themselves, helping reduce emissions, enhance grid reliability, and stabilise energy prices.
"Having batteries at the right locations and then operating and commercialising them as a network – as one network, not as one battery – is really a big differentiator," Bazen says. "It's also a big solution to society because we all realise that grid upgrades are not going to be happening on time, if at all, that electricity demand will continue to be further fragmented, that electricity supply will be further fragmented.
"As more renewables come online, then having access to BESS networks at the right location is essential."
Solar to storage
Return was founded by serial renewable energy entrepreneurs who previously built and sold solar business, Sunrock. Following that sale they turned their attention to electron storage. Their successful track record meant securing €50m–€70m in seed capital from Dutch family offices to launch Return's battery storage platform five years ago came relatively easily.
The strategic approach from the outset was methodical: identify markets with high grid volatility, enter through both acquisition and organic development, and build a network rather than chase isolated projects. The initial target markets were Germany, Belgium, the Netherlands and Spain.
"We applied a dual engine approach," Bazen explains. "Because we had extensive prior experience in development, the plan was to buy an existing developer – ideally in each country – and in parallel, start our own development engine."
The strategy played out first with the acquisition of Dutch market leader SemperPower, which is now fully integrated with all operations running under the Return brand. In 2024, the pattern was repeated in Germany with a €50m investment and commitment in Hamburg-based J&P Batterie Projekte. With a pipeline of over 4GW of storage projects, J&P was well positioned to accelerate Return's European energy storage plans. The partnership expanded Return's presence in the country where it had inherited an office in Munich through the SemperPower platform.
A joint venture in Spain, with Benbros, followed. The agreement included an initial package of 210MW in 10 projects that are well advanced in development. The partnership bolstered Return's expansion in the Spanish market, where it already operated in the sector of large-scale solar grid-connected projects and solar industrial self-consumption through its subsidiary, Ekhi.
In the Netherlands, Return formed a JV with Lion Storage, the developer behind the Mufasa project in Flushing – at 364MW, 1457MWh BESS capacity with four-hour duration, one of Europe's largest battery installations.
Return now has 70MW of operational capacity in the Netherlands, with another 450MW under construction split between Mufasa and the 100MW Antares project in Rotterdam. The company has grown from 30 people to around 90 in the past 18 months.
APG partnership
In 2025, Return was ready to take the next step in institutionalising its shareholder base and began a capital raise that resulted in a minority equity investment from APG, the investment arm of ABP, one of the world's largest pension asset managers. APG committed €300m with scope to deploy more capital. The deal, which closed in late 2025, was led by Santander on the financial advisory side.
"We basically secured our funding for the coming years to execute our business plan," said Bazen. "APG's committed capital not only gives us stability and tailwind to drive growth across the countries we have identified but we see them as a partner that takes a long-term view on its investments and is aligned with us on things like mission and purpose."
The APG capital follows around €600m already committed to the business before the pension fund's entry, and positions Return to accelerate development across its core markets. The company's pipeline includes 250 potential sites representing 30GW of theoretical capacity, with seven to eight gigawatts in what Return terms active development – projects with visibility on grid connections and commercial offtake.
Bazen is clear that Return's model is long-term hold. "We are developing and expanding an independent Pan-European storage network and operate it for our customers," he says. The company has no near-term exit strategy, reflecting Return’s long-term approach and its strategic partnership with APG, which enables continued European growth. Though Bazen acknowledges that as the market globalises, Return may eventually need additional partners or consider a listing to remain competitive.
Germany leading growth
Return expects two-thirds of its targeted 5GW by 2030 to come from Germany. The German opportunity is driven by market fundamentals: high renewables penetration, volatile pricing, and a federal structure that, while complex, offers multiple entry points for developers who can navigate regional permitting regimes – complexity that Return addresses through its local expertise.
In September 2025, Return announced its partnership with Berlin-based BESSMART to acquire four strategic battery energy storage locations in Eastern Germany, totalling 310MW and 670MWh. Together, these systems will provide enough storage capacity to manage the equivalent of powering nearly all of Berlin's streetlights for a full night. Commercial operation is scheduled for 2027.
In terms of other markets, Bazen said: "We're open to look at any type of market, but we will only do it from a commercial approach. It will be driven by our customers committing to storage capacities."
Customer-first commercialisation
Return's go-to-market strategy distinguishes it from developer-traders operating batteries on the merchant market. Instead, Return has spent five years building a sales funnel covering over 80 accounts, targeting customers who need storage services but don't want to own the assets.
"We're independent. We don't compete with our customers," Bazen says. "We allow them to continue with their core business, and we do our core business, which is operating batteries according to customer needs and in the right locations."
Return has identified three core customer segments: utilities managing volatile renewable supply and gas-fired generation; strategic end users like railways, data centres and industrial zones seeking energy security; and traders looking to optimise positions around price spreads.
Utilities have proven the stickiest customers. They face constant imbalances across their supply chain as they manage wind and solar generation, adjust gas-fired power plants to volatile demand, and handle grid congestion. Return's storage allows them to smooth these imbalances under seven to 10-year contracts without building their own battery infrastructure. Committing to long contract tenors underpins project financing.
In the long term, Return targets a revenue mix of 80%–90% contracted and 10%–20% short-term exposure. It can currently focus on long-term contracts, however, given strong offtake demand, leaving the potential value from the merchant market to its customers.
"We don't want to compete with them," explained Bazen. "Our main focus for now is to develop our network across Europe: closing the business cases, getting a fair and solid return, and moving on to develop our network."
PF evolution
Return's financing strategy reflects both the level of maturity in battery technology and lenders' understanding of storage economics. The Mufasa project, backed by Macquarie Capital as lead investor, listed infrastructure investor TINC, existing Return investors and six banks, with Santander as financial adviser, marked a milestone for the company.
"It's a lot of blood, sweat and tears for such a small company to take these major big projects," Bazen admits. "In our case we had Mufasa and Antares going to financial close at the same time."
The €500m Mufasa scheme was project-financed in February 2025 with €350m of non-recourse debt from Santander, ING, Rabobank, ABN AMRO, Triodos and ASR.
The €85m 100MW/200MWh Antares BESS in Waddinxveen was financed in April 2025 with a debt package led by ING and including investments from Meewind and Nationaal Groenfonds. The project will be connected to TenneT's national grid in 2026 and will receive revenues from multiple capacity offtakes with the grid operator, traders and renewable power providers including Vattenfall.
In November 2025, the 13MW/29MWh battery energy storage system in Brietlingen, Lower Saxony, scheduled for completion by the end of 2026, reached financial close with support from Deutsche Anlagen-Leasing and its financing partner Deutsche Leasing Finance.
Two further closings are being worked on in Spain alongside those in the Netherlands and Germany and Bazen hopes there will be tens of closings in 2026. As the portfolio scales, Return is exploring portfolio financing structures that would reduce equity deployment per project and accelerate network buildout.
"We try to deploy as little equity as possible per project because it will further accelerate our network development," Bazen says. "At a certain point there will be a tipping point – if you're at a certain scale and size, you'd be looking at portfolio financing at the right moment."
The company's procurement strategy has focused on building framework agreements with battery suppliers – 90% of global batteries come from four Chinese manufacturers –and Return has hired Chinese nationals to strengthen supplier relationships and access the latest technology.
Its batteries generate 300,000 data points across its operating fleet. That operational data is helping prove to lenders that degradation curves match projections and that technology risk is manageable.
Network thesis
Return's core proposition – that interconnected storage networks are more valuable than standalone assets – is being tested as European grid constraints intensify. The company believes that by operating batteries as a virtual network, it can optimise electron flows for both customers and grid operators, helping manage congestion without waiting for transmission upgrades that may never arrive.
"We are able to bring our customers into a virtual basket above the assets," Bazen explains. "Without jeopardising the individual contracts of customers, we're able to push the electrons where it's best – obviously for the customer, but also for the grid operators – to make sure the grid can be fully optimised."
It's a complex pitch, but one Bazen believes resonates with policymakers increasingly concerned about grid stability as coal and gas phase out and renewables ramp up. "If you have a network of batteries in a region, it is much more valuable for the grid operator and for the customer than having one battery or no battery," he says.
Return is well on track to meet future demand with a pan-European storage network. Whether Return can execute on its 5GW ambition – and whether its network thesis demonstrates economic viability – remains to be seen.
But with over €2bn in long-term customer contracts, improving project finance conditions, and APG's capital behind it, Return has positioned itself to test the hypothesis at scale.
As battery costs continue to fall and grid constraints tighten, the company's dual-engine model – buying local expertise while building Pan-European infrastructure – may offer a blueprint for consolidation in a market still fragmented by national boundaries and regulatory complexity.
