The inability of the Spanish power grid to cope with extremely high volumes of solar power has become a key factor in Monday's catastrophic power outage, former regulators and experts say, according to the Financial Times, writes UNN.
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About 55 percent of Spain's supply came from solar sources when 15 GW of electricity disconnected from the grid in just five seconds on Monday afternoon, causing a widespread power outage in Spain and Portugal.
Several European experts said Spain appeared to lack sufficient firm power - an easily accessible, reliable source of energy from sources such as fossil fuels or nuclear power that can be reduced or increased - to turn on when the grid frequency dropped sharply at 12:33 p.m. local time on Monday. The frequency, the rate at which the electric current changes, must be kept stable for the grid to function.
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Spanish grid operator Red Eléctrica said it still does not know the exact cause of the outage. CEO Beatriz Corredor denied that renewable sources had "made the system more vulnerable" in an interview with El País on Wednesday.
But André Merlin, founder and former CEO of French grid operator RTE, told the Financial Times: "Two-thirds of production [electricity in Spain] consisted of uncontrolled resources. These uncontrolled resources... do not contribute to the stability of the internal electricity system."
Jorge Sanz, a leading former Spanish energy official and board member of the International Energy Agency, told Spanish television on Wednesday evening that an excess of electricity may have initially caused the problem. Normally, the grid operator would have dealt with this by asking traditional power plants to curb their output, but this was not possible because there were so few power plants on the grid, Sanz said.
This would be followed by a shutdown of electricity generation to avoid damage to equipment, which in turn would lead to a shutdown.
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Sanz said: "There was an imbalance of supply. [The grid operator] needed to cut off power, but when it resorts to fixed capacity services to reduce the load, it can barely do so because they were barely connected."
Last month, Transport Minister Oscar Puente said via his X account that an "overvoltage in the grid" caused a failure that caused some high-speed rail lines to fail for several hours.
Meanwhile, one energy advisor close to the European Commission also said experts are looking into whether the country's high reliance on renewable energy and lack of fixed capacity to balance intermittent supplies contributed to the power outage.
Grid operators must constantly balance electricity supply and demand to keep the grid frequency stable and avoid damage to equipment or outages. Such stability is easier to achieve with fossil fuel-fired turbines, hydroelectric power plants or nuclear power than with renewable technologies such as solar power. Spain's grid frequency dropped sharply below the optimum level of 50 Hz at 12:33 p.m. local time on Monday.
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Reliance on solar power during the outage has led to criticism of Red Eléctrica. Usually, about a fifth of the country's supply comes from solar power.
Sanz, a former advisor on alternative energy transition in the Spanish government, said grid management was "poor" because not enough nuclear, hydro or fossil fuel-generated electricity was planned to balance the system. Of the planned 26 GW of electricity supply on Monday, only 5 GW came from continuous sources.
The Brussels advisor pointed to Red Eléctrica's own 2024 annual report, which stated that outages caused by "high penetration of renewables" without sufficient "necessary technical capabilities to adequately respond to disruptions" pose a risk to the system.
Merlin was less critical of the operator, but said renewable energy policies should be reviewed in light of the incident. "I don't think the Spanish or Portuguese operators managed poorly. Simply put, we need to be careful with policies of maximizing development and maximizing the use of intermittent renewable energy as opposed to more traditional means."
Some experts say the outage may have been caused by a cascade of events, not a single problem. "We usually find several things that went wrong at the same time," said Christian Ruby, secretary general of the Eurelectric industry body.
Merlin suggested that solar power plants failed first. He offered a different theory than Sanz's idea of a surplus of solar energy, suggesting that heavy cloud cover may have led to a sharp drop in production at some solar power plants, which affected the grid frequency.
Corredor of Red Eléctrica, who is under intense pressure to explain what happened, said the company has not yet determined the cause of the outage and cannot say that solar power plants are behind the outage. She said the operator observed a sudden shutdown in the southwestern region of Spain, where many solar power plants are located.
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But she launched a strong defense of Spain's renewable energy systems and pointed to the unreliability of other energy sources, including nuclear. "[Renewable sources] are not dangerous technologies. The proof is that the system works with renewable sources every day... It is not true that wider penetration of renewable sources has made the system more vulnerable," she noted.
In addition to reducing carbon emissions and nuclear waste generation, Spain's renewable energy grid has helped lower energy prices compared to many other European countries, thereby helping industry and economic growth.
The Spanish government of Pedro Sanchez has developed plans to increase renewable energy production to 80 percent of electricity generation by 2030, compared to more than half in 2023.
But Sanchez has been criticized by opposition politicians for plans to phase out Spain's expensive nuclear grid, and several experts, including Merlin, have advocated for greater use of nuclear power in Spain to ensure energy security.
Iberdrola CEO Ignacio Galan told analysts on Tuesday that nuclear power is the "least expensive solution to ensure system stability."
Another solution is to accelerate the deployment of battery technologies or storage systems or improve connections with other countries to import more electricity.
"The main focus for the country should now be to increase storage capacity," said Pratiksha Ramdas, an analyst at Rystad Energy.
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