Former regulators and experts say that the power grid in Spain that cannot manage solar power cannot manage the supply of solar energy is a key factor.

About 55% of Spain's supply comes from solar sources, when 15GW of 15GW of power generated was disconnected from the grid in just five seconds on Monday afternoon, triggering widespread shutdowns of power systems in Spain and Portugal.

Several European experts say Spain appears to lack sufficient corporate capabilities – reliable energy supply that can be reduced or raised from fossil fuels or nuclear sources – when the frequency of the power grid dropped sharply at 12.33pm on Monday. Frequency is the rate at which currents alternate, and a stable grid function must be maintained.

Spanish grid operator Red Eléctrica said it still doesn't know the exact cause of the power outage. CEO Beatriz Corredor denied rebate that renewable energy “makes 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 the production of (Spanish Electricity) is made up of uncontrollable resources. These uncontrollable resources. These uncontrollable resources ... do not contribute to the stability of internal electrical systems."

Jorge Sanz, a former Spanish energy official and board member of the International Energy Agency, told Spanish TV on Wednesday night that power supply may have caused problems initially. Usually, grid operators manage this by asking traditional plants to regulate their yields, but this is impossible because few plants are online, Sands said.

The power connection to the development will then be disconnected to avoid damage to the equipment, resulting in a power outage.

"The supply is unbalanced. (Grid operators) need to reduce the supply of electricity, but when it resorts to enterprise facilities to reduce loads, it is hard to do so because they have little connection."

Last month, Transport Minister Óscar Puente revealed through his X account that “excess voltage in the network” caused failure, leaving some high-speed rail lines unable to operate for several hours.

Meanwhile, an energy adviser close to the European Commission also said experts are exploring the country’s high regenerative capacity dependence and the lack of balanced intermittent supply to help blackout power.

Grid operators must constantly balance power supply and demand to maintain stable frequency of the grid and avoid damage to equipment or interruptions. Turbos powered by fossil fuels, hydropower or nuclear energy are easier to achieve than renewable technologies such as solar energy. Spain's grid frequency dropped sharply at its best 50Hz speed of 12.33 on Monday afternoon.

Reliance on solar energy in the event of a power outage leads to criticism of the red Eléctrica. Typically, one-fifth of the country's supply comes from solar energy.

Sanz, a former consultant to the energy transition to the Spanish government, said the “bad management” of grid management is not enough nuclear, hydropower or fossil fuel energy to balance the system. Of the 26GW of the electricity supply scheduled on Monday, only 5GW comes from non-contingent sources.

Brussels-based consultants noted that the Red Eléctrica's own 2024 annual report, which said that "high renewable penetration" caused disconnection without sufficient "technical capabilities necessary to fully deal with harassment" is a risk to the system.

Merlin is not very critical of the operators, but says renewable energy policy should be reviewed based on the incident. "I don't think Spanish or Portuguese operators are well managed. In short, we need to be cautious about the policies that maximize development and the maximum use of intermittent renewable energy to harm more conventional means."

Some experts say a series of events, rather than one problem, could be the cause of the power outage. “What we usually find are a few things that have problems at the same time,” said Kristian Ruby, secretary general of the industry body Euleelectric.

Merlin suggests that solar power plants may be the first to fail. He offers a different theory from the idea of ​​oversupply of solar energy in Sanz, suggesting that heavy cloud cover may prompt rapid decline in production in some solar power plants, directly affecting grid frequency.

Red Eléctrica's Cordor is subject to a strong explanation, saying the company has not determined the cause of the blackout and cannot say that the solar power plant is out of the way. She said operators have observed abrupt disconnection of many solar power plants in the southwestern region of Spain.

But she put a harsh defense of Spain's renewable systems and pointed out the unreliability of other energy sources, including nuclear energy. "(Renewables) are not unsafe technologies. It proves that the system operates in renewables every day... Incorrectly, higher renewable energy penetration makes the system more vulnerable."

In addition to reducing carbon emissions and the production of nuclear waste, Spain's renewable energy network is also able to promote lower energy prices compared to many other European countries, thus contributing to industry and economic growth.

The Pedro Sánchez government has set up plans to increase renewable energy production to 80% of electricity generation by 2030, and more than half of it in 2023.

But Sánchez has come under fire from opposition politicians for planning to phase out Spain’s expensive nuclear networks, with several experts, including Merlin, advocating more use of nuclear power in Spain to ensure energy security.

Ignacio Galán, executive chairman of Iberdrola, told analysts on Tuesday that nuclear energy is "the cheapest solution to ensure system stability".

Another solution is to accelerate the rollout of battery technology or storage systems, or improve connectivity to imported more power with other countries.

"At present, more storage capacity should be the main focus of the country," said Pratheeksha Ramdas, an analyst at Rystad Energy.

Other reports by David Sharrock in Madrid