On April 28, 2025, Spain and Portugal experienced a catastrophic blackout that left over 50 million people without power for up to 15 hours. The incident cost Spain an estimated $1.82 billion in economic output and damages. Fortunately, for Spain, the outage occurred on a mild spring day, not during a heat wave or a winter storm, and their black start operations brought the grid back online relatively quickly. The consequences were far less severe than they could have been.
Six months later, the various causes of the event have mostly been sorted out. Here is the breakdown and the lessons Texas and the rest of the U.S. should learn from this event.
What Happened on April 28th
Energy analyst Deric Tilson’s offers the most accurate and concisely written timeline we’ve seen so far, which reveals how Spain’s heavy reliance on intermittent generation created the conditions for catastrophe. By the middle of the day, which is when the outage occurred, over half of Spain’s 32 gigawatts of generation came from solar alone. Electricity prices went negative as Spain exported surplus power.
But at 12:03 PM, a solar plant in Badajoz began experiencing voltage oscillations from a malfunctioning inverter. The grid operator, Red Eléctrica de España, tried to manage the problem by changing the import and export flows into France, which didn’t work, and by bringing on a nuclear unit and some gas units, which didn’t happen in time. In other words, a single point of failure—this time a faulty inverter, much like the faulty transmission relay that led to the Great Northeast Blackout in the 1960s—led to other failures and eventually collapse.
By about 12:30 PM, rising voltage on the system led to more disconnections of various power plants, and the grid frequency began to drop. Spain lost 2.5 gigawatts—10% of its total generation—in just 80 seconds. As energy analyst Bjorn Lomborg noted, all of these initial generation losses were solar and wind facilities.
Traditional spinning generators produce inertia that dampens grid fluctuations, but most wind and solar installations use inverters that “follow” the grid rather than “form” it. When voltage or frequency goes outside preset ranges, safety mechanisms automatically disconnect these resources, creating a deadly feedback loop. Without enough spinning generators on the system, grid operators could not bring the frequency back into a safe range fast enough. By 12:33:24—just 30 minutes after initial oscillations—the grid had completely collapsed.
The Warning Signs Persist
Spain’s grid is still showing dangerous warning signs—and Texas should be paying close attention. According to Bloomberg, in early October, Red Eléctrica requested urgent changes to operating procedures after experiencing concerning voltage swings that threatened another blackout. Abrupt changes in scheduled production, particularly from wind and solar power plants, are creating ongoing challenges for grid stability.
While the public statements coming out of Spain have repeatedly denied that a lack of spinning generation and too much wind and solar was the primary cause of the problem, actions speak louder than words. Before the April blackout, Spain would routinely turn off most of its gas-fired units, sometimes having only 4 or 5 units running at a given time. The number of gas units online appeared to be in the singles digits at the time of the blackout. Since the blackout, Spain is always keeping at least 17 or 18 gas units online.
Could It Happen in in the U.S. and in Texas?
The North American Electric Reliability Corporation (NERC) identified problems in Spain that apply to Texas and other parts of North America: insufficient voltage regulation, poor tolerance of inverter-based resources to voltage oscillations, and potential gaps in operations planning. NERC warned that if the U.S. grid had seen a similar situation before April 2025, parts of the American grid could have collapsed.
Texas faces similar physics as the Iberian peninsula, with high penetrations of wind and solar and, unlike the limited connections Spain has with France, no synchronized connections to neighboring grids. In fact, disturbances like the one that brought down the Iberian grid have happened multiple times already in Texas, with significant losses of generation that required swift action from grid operators to prevent outages.
Fortunately, Texas does have two advantages over Spain. First, it has a lot of short-duration energy storage that, while not very useful for long-term resource adequacy, is very effective at injecting large quantities of power into the grid in less than a second to support grid frequency. Those sorts of power injections could have saved Spain when its system was collapsing. It also has dedicated programs to ensure that adequate frequency response is always available.
Second, the Texas grid operator, ERCOT, is proactively working to address the problem. It is implementing a new protocol to require wind and solar facilities to install inverters that ride through disturbances without tripping offline like the facilities in Spain did. It is also spending close to $1 billion to install synchronous generators throughout West Texas by the end of 2027 to provide exactly what Spain was lacking: the inertia and voltage support needed to keep the grid frequency stable and prevent fluctuations
If Wind and Solar Don’t Pay for Grid Reliability Costs, You Will
The lesson from Spain is that while it is technically possible to integrate high levels of wind and solar into a grid, the programs needed to support the grid cost a lot of money and require a lot of attention and effort. Spain built a grid around intermittent generation without holding those sources accountable for reliability and failed to make the necessary investments.
Texas regulators are making the necessary investments and hopefully will keep doing so quickly enough to keep up with expanding wind and solar generation, but unfortunately, the costs are socialized to ratepayers in the form of pass-through regulatory charges. Wind and solar facilities should have to pay for what they lack relative to gas, coal, and nuclear generators, but policymakers have been afraid to force the issue. Passing on the costs through hidden regulatory schemes is a much easier political solution.
Add in the cost of volatility in the ERCOT energy market, which Life:Powered estimates is close to $2 billion in an average year, and the cost of new transmission to connect distant wind and solar facilities, which is over $1 billion annually and set to rise, and it is easy to see why Texans’ electricity bills are still rising despite the flood of “cheap” energy from wind and solar. Since those facilities do not provide reliability attributes that gas, coal, and nuclear generators provide by default, the rest of us are paying for it.
The bottom line is that these reliability investments are needed to avoid outages, and if the generators aren’t made to pay for what they lack, ratepayers will have to pay for it. What’s needed going forward is to ensure that generators fail to meet reliability standards should face financial penalties through reduced market revenue, with proceeds redirected to generators that exceed the standard. The Legislature passed legislation in 2023 to require new generators to meet a reliability standard, but the requirement must be extended to all generators to ensure Texas ratepayers are not going to be caught holding the bag.
