Marta Sofía Díez Domínguez works with large corporate operators across the Iberian Peninsula, many of whom were impacted by the energy blackout that made international headlines on March 28, earlier this year.
Supporting organisations with major decarbonisation and energy transition goals, Marta works with an international team of energy specialists, policy makers and industry-leaders to ensure she can deliver carbon reduction and energy transformation with impact and at scale.
We need flexibility more than capacity...
Spain’s recent blackout, described by grid insiders as one of the most significant disturbances in years, has laid bare the vulnerability of the continent’s most renewables-advanced power systems.
The incident, which caused widespread outages across several regions, is not thought to have been driven by a shortage of generation but by a failure of coordination and flexibility within an increasingly decentralised grid.
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(Marta Diez, acting as Sustainability Spokesperson of the Governing Board for the
British Chamber of Commerce for Spain)
But despite the severity of the issue and the resolve to fix it, there are still problems impacting the Spanish grid.
The country's grid operator, Red Eléctrica de España (REE), recently detected steep voltage swings in the system ,capable of affecting power supply across the country.
REE responded swiftly by tightening ramp-rate controls for solar and wind farms.
Previously, renewable assets were permitted to go from zero to full output within two minutes. Now, they will have to do so over a much slower 15-minute interval — an emergency measure designed to dampen voltage swings and maintain frequency stability.
REE also called for urgent technical measures to prevent further grid disruptions. In early October, market regulator CNMC announced a public consultation to introduce temporary stabilisation steps ahead of permanent reforms.
In a statement, the National Commission on Markets and Competition, said:
"According to the information provided to the CNMC by the system operator (REE), the rapid voltage fluctuations recorded in the last two weeks, even though the voltages are always within the established margins, can potentially trigger demand and/or generation disconnections that end up destabilising the electrical system."
Alongside these recent disruptions, it was also confirmed that the April 28 Iberian blackout was Europe’s first major outage caused by excessive voltage, though a number of other questions remain.
A full report on the issue can be read here: Entso-E report.
So, how have we got here?
When Spain’s grid has long been considered a leader in integrating renewables, what has gone wrong?
More than 50% of its generation now comes from low-carbon sources, with solar output at times exceeding total midday demand.
Yet the blackout, and the ongoing issues, reveal a structural issue that many decarbonising systems will soon face, particularly the UK as it races toward a renewables-dominated grid.
When variable renewables surge and plunge in tandem, traditional system balancing tools, from pumped hydro to gas peakers, can no longer react quickly or granularly enough to keep voltage and frequency within safe limits.
In Spain’s case, the rapid simultaneous response of thousands of distributed plants created voltage oscillations that cascaded through the network.
REE’s “SOS” request for generation smoothing underscores a wider problem.
Grid codes and operational protocols, many written decades ago, are struggling to keep pace with the dynamics of modern renewable fleets.
For the UK, the lesson is clear. National Grid ESO’s future system operator (FSO) model must prioritise investment not just in transmission expansion, but in operational flexibility.
(The UK can generate over 75% of its own energy during peak conditions, but without grid flexibility this may cause more problems than solutions)
Dynamic voltage control, synthetic inertia, fast-acting storage, and distributed demand response.
The UK’s ambition to run a zero-carbon power system by 2035 will require real-time coordination of millions of distributed assets, from rooftop PV to EV chargers, underpinned by advanced digital control systems and market-based signals.
Flexibility markets, long discussed, now need to mature into critical national infrastructure.
Spain’s blackout shows that technical fixes alone, slower ramp rates or revised inverter settings, buy time, but not resilience.
True system stability will depend on integrating storage at scale, incentivising flexible demand, and ensuring cross-border interconnectors can shoulder volatility when domestic supply falters.
In short, Spain’s blackout is not an Iberian anomaly.
It's a European warning.
As renewables accelerate, the continent’s challenge is no longer generating clean power, it’s keeping it balanced, controlled, and reliable every second of the day.
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