Spain’s recent proposal for data centres to match hourly demand with renewables could be the catalyst the country’s energy storage market has been waiting for, argues Ignacio López Martín from developer Capflex Energía.
Spain has spent three years arguing about whether merchant energy storage works. At the end of August, the argument became irrelevant, and it happened inside a document that most of the energy storage industry has not read, because it is filed under data centres.
The draft royal decree, whose public consultation has now closed, does something that no European regulator has done this bluntly. It ties grid access for data centres of 1MW and above to hourly renewable matching. Not an annual average, not certificates bought in December to square a spreadsheet: 80% of the electricity consumed in each individual hour has to be backed by renewable generation produced in that same hour.
On top of that it demands additionality, with the supplying plants commissioned no more than eighteen months before the facility starts operating. Miss it and you do not lose a subsidy. You pay surcharges on your network tolls and system charges that go as high as 500%, and if you keep falling well short for five consecutive years, you can lose your grid access permits, which for a data centre is the same as losing the business.
Try Premium for just $1
- Full premium access for the first month at only $1
- Converts to an annual rate after 30 days unless cancelled
- Cancel anytime during the trial period
Premium Benefits
- Expert industry analysis and interviews
- Digital access to PV Tech Power journal
- Exclusive event discounts
Or get the full Premium subscription right away
Or continue reading this article for free
Read that as an energy storage person rather than as a digital infrastructure person and the consequence is immediate. Hourly matching cannot be met with solar alone, and the reason is not commercial, it is astronomical. A data centre draws its flattest, most stubborn load at three in the morning in December, which is precisely when a Spanish solar plant produces nothing at all. Wind helps and does not solve it, because the worst hour of the year for this obligation is a still winter night, and those exist. The only way to be compliant in every hour of a calendar year is to move energy across hours, and moving energy across hours is what a battery does.
So the decree, which mentions storage only in passing, in the clauses on metering and on what a valid PPA has to list, has done what three years of investment cases could not. It has turned hybridisation from a way of improving an internal rate of return into a condition for holding a licence.
That distinction matters more than it sounds. An optimisation is discretionary. It survives inside an investment committee only as long as the numbers hold, and it is the first thing cut when the capex line gets tight. A compliance requirement is not discretionary. It gets financed at a different cost, it gets contracted on longer terms, and crucially it gets a counterparty who cannot walk away, because walking away means their facility does not connect.
I argued in these pages in June that the Spanish BESS pipeline was real and that the private equity models being applied to it were wrong, because they were priced as merchant arbitrage plays with volatile revenue and no anchor. The gap in that argument, fairly pointed out to me at the time, was the anchor. Who exactly signs a long contract for flexibility in Spain, and why would they?
The decree answers that question. The counterparty is the hyperscaler that wants a connection in Aragon or Madrid, and the reason is that without contracted, hour-matched, additional renewable supply, they do not get one.
Time is of the essence
There is a timing consequence too, and it is the part I would pay attention to if I were allocating capital this quarter. The additionality rule requires the supplying plants to have been commissioned no more than eighteen months before the data centre begins operating. Work backwards from any facility hoping to be live in 2028 and the generation and storage serving it has to be under construction now. Not consented. Not in a pipeline slide. Under construction.
That is exactly where Spain is weakest. At the end of January, 24.3GW of batteries held grid access permits, according to Red Eléctrica’s data. In late August, 260MW were connected. About one per cent. The pipeline I described in June is real. It is also, so far, almost entirely on paper. The bottleneck is no longer the permit. It is everything that has to happen between the permit and the first megawatt.
And more permits are coming. On 23 September the ministry announced consultations on how to allocate up to 11GW of grid capacity at Spain’s “just transition” nodes, the connection points left behind by closed coal and nuclear plants, which had been held in reserve until now. For 15 of them, it proposes the simplest method there is: first-come, first-served. It is a good decision, because it frees grid that was serving nobody. But unless “first” means first to build rather than first to file, with construction milestones that hand the capacity back automatically when a project stalls, it risks producing more of what the battery queue already has in abundance: permits that never become megawatts.
Meanwhile, the projects that could actually meet the decree are priced as if the only buyer were the wholesale market. Ready-to-build projects in Spain are valued off capture rates and cannibalisation curves, which is to say, the assumption that their output competes with everyone else’s at the worst possible moment. That assumption is about to stop being true for any megawatt that ends up inside a data centre contract, and the market has not repriced it, because the industry reading the decree and the industry that owns the assets are not the same industry and do not read the same press.
Two cautions before anyone builds a model on this. The decree is still a draft, its consultation closed with plenty of criticism, and the percentage, the thresholds and the transition periods can all move before it is approved; Spain’s renewable associations APPA and AEE have already asked for the hourly requirement to be relaxed. And hourly matching is genuinely hard to verify at scale, which means the metering and settlement framework will decide how demanding this really is in practice. A rule that is unenforceable is a rule that gets ignored.
But the direction is not going to reverse, because the political problem it solves is not going away. Spain is being offered enormous quantities of foreign capital to host computing load, and it has a public that remembers last year’s blackout and a grid that is already the binding constraint. Conditioning access on firm, local, additional renewable supply is the only version of that deal a government can defend.
For those of us who have spent years explaining that storage is infrastructure rather than a trading position, this is the first time the regulator has agreed in writing.
About the author
Ignacio Lopez Martin is a Spanish energy entrepreneur. He co-founded Cable Energia, the EV fast-charging platform acquired by Shell in 2022, chairs the board of a Spanish storage developer in a personal capacity, and is currently assembling a renewables IPP in Spain.
