The starting point is the draft Royal Decree that the Ministry for Ecological Transition and the Demographic Challenge (MITECO) submitted to public consultation on August 27 , with new energy, environmental and digital sovereignty conditions for data centers with at least 1 MW of access power.
Among other requirements, the text stipulates that these facilities must cover at least 80% of their energy consumption with new renewable generation and time-of-use pricing , through self-consumption or supply contracts. Power Purchase Agreements (PPAs) must extend for at least ten years, identify the linked facilities, and also detail any associated energy storage when it is part of the scheme.
This design could alter one of the most difficult variables to resolve for BESS in Spain: how to ensure income for enough years to obtain funding .
For Ignacio López Martín , partner and investor at Vida Sustainable Ventures and partner and managing director of Capflex Energía , the challenge is not only in getting a battery to RTB, but in demonstrating what cash flow can sustain the investment once it is built.
“If you have an RTB battery project, you know the charging and discharging times, it is associated with generation, and you have a PPA with a set price signed by a bankable counterparty, you can build a financial model,” he explains.
The barrier is not so much technological as economic. In a purely merchant asset, profitability depends on the differential between loading and unloading times, the markets in which it participates, and how flexibility services evolve. Furthermore, a massive influx of storage capacity will ultimately alter the very curves on which these returns are currently calculated.
A long-term contract does not eliminate that exposure, but it can provide a more stable income base on which to structure debt .
A 24/7 demand that can be multiplied by six
The magnitude of that opportunity changes when you look at the expected growth of data centers.
At the end of 2025, Spain had 439 MW of installed IT capacity in commercial data centers , compared to 355 MW a year earlier. SpainDC projects that this capacity could reach 2,537 MW by 2030 , almost six times the current level, and mobilize up to €66.9 billion in direct and indirect investment during that period.
The growth is not concentrated in a single hub. Madrid remains the most developed market, while Aragon is gaining ground in hyperscale projects, and Catalonia maintains a strong position in colocation and new loads linked to artificial intelligence. In recent months alone, initiatives such as a campus of up to 150 MW in Aragon , driven by Krolmap, have been announced, along with new developments in Madrid, Alicante, Toledo, and Catalonia.
This growth makes the hourly consumption profile a central issue. A data center maintains high demand practically 24 hours a day, while renewable energy production varies depending on the time of day and available resources. Photovoltaics concentrate their generation during the day, and wind power also doesn't offer a constant output curve.
It is precisely in that difference that López Martín places storage.
“For a data center, which has virtually continuous consumption, to be able to supply itself with that level of renewable energy, I understand that there will have to be a PPA and associated storage,” he argues.
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The BESS can shift some of the production to times when the contracted generation doesn't meet the center's load. But the appeal for the developer doesn't end with that technical function: that same consumer can provide a contractual commitment for the duration of the financing required .
The specific structure will be crucial. Price, duration, counterparty solvency, guarantees, time frame, and risk distribution will define what portion of the flow can be considered sufficiently protected against future volatility.
The strain on the grid provides another measure of the phenomenon. The government acknowledges approximately 12 GW of electrical capacity already granted to data centers for transmission and distribution , a figure distinct from the installed IT capacity (MW) and far exceeding the deployment that is expected to eventually materialize. It is precisely this gap between permits and operational capacity that underlies the attempt to condition new access on additional generation and adherence to schedules.
Capflex Energía is already studying the model
The convergence between these two industries is not limited to a regulatory hypothesis.
Capflex Energía is analyzing raising capital to acquire RTB renewable projects, incorporate batteries through hybridization, and develop PPAs with data centers , as confirmed by López Martín.
The strategy brings together three pieces that until now could be developed separately: generation ready to be built, capacity to shift electricity between hours and a large demand willing to contract supply for several years.
For an independent BESS developer, this combination can bypass one of the sector's main filters. A large utility can initially rely on its own balance sheet and tolerate greater market exposure; those needing project finance must first demonstrate what revenue will allow them to service the debt.
Spain already offers a benchmark for the growing importance of contractual stability. In July, Grenergy secured €100 million in senior non-recourse financing for Oviedo, its 154 MW, 618 MWh stand-alone BESS project in Asturias, with Santander and Sumitomo Mitsui Banking Corporation. This transaction followed the signing of a ten-year financial tolling agreement with an international energy company with an investment-grade rating.
The agreement does not necessarily replicate the scheme that data centers will use, but it does show what banks are beginning to value in this type of asset: a sufficiently long contractual horizon and a counterparty capable of reducing uncertainty about future income .
The risk that everything will end up in certificates
The opportunity will also depend on how the regulation ultimately plays out.
“The first rule may be good, but we need to go further to prevent it from all just being reduced to a buying and selling of certificates and to ensure that it actually contributes to the deployment of storage,” says López Martín.
The draft attempts to limit this risk through three elements: additionality, time-based correlation, and explicit identification of the plants linked to the contract. It also excludes coverage whose renewable origin is justified solely by guarantees of origin.
The difference is significant. If compliance results only in documentary accreditation, the effect on new infrastructure will be limited. If, however, it requires structuring PPAs of ten years or more, new generation storage, and the ability to adapt its production to consumption , digital expansion could end up creating a new type of customer for BESS.
With IT capacity that SpainDC expects to increase almost sixfold by 2030, the opportunity for batteries lies not only in meeting increased electricity demand.