Around 9:30 pm on Sunday, the Electric Union reported that the National Power System (SEN) was interconnected from Pinar del Río to Guantánamo, thus completing a recovery process that required more than 30 hours of uninterrupted work by sector specialists, after a new blackout plunged Cuba into darkness the previous day for the second time in just one week.

The announcement crowned a day that had begun with uncertain prospects and that, step by step, added the necessary pieces to reassemble the national energy puzzle.

"MICRO-ISLAND" IN LAS TUNAS MAINTAINED THE ESSENTIALS

Since midday, official reports painted a picture of gradual but sustained progress. The Ministry of Energy and Mines (MINEM) reported at 6:00 pm that Unit 1 of the Santa Cruz thermoelectric power plant, Units 3 and 4 of the “Carlos Manuel de Céspedes,” the Energás Boca de Jaruco and Varadero plants, and the Antonio Guiteras thermoelectric, in Matanzas, were online.

These additions, which complemented the microsystems that had maintained vital services in western and central Cuba throughout the morning, created the necessary conditions to extend the interconnection to eastern Cuba, the region most affected by the prolonged blackout.

At 7:42 pm, the National Electric Union announced that the system was interconnected from Pinar del Río to Santiago de Cuba, and that work was underway to connect Granma and Guantánamo. Less than 20 minutes later, at 7:59 pm, confirmation arrived: Granma was integrated into SEN. The complete interconnection, including Guantánamo, finalized shortly before 9:30 pm.

While the country was moving toward interconnection, Las Tunas was undergoing its own recovery process within the limitations of eastern Cuba. By midday on Sunday, the province was maintaining its energy micro-island with a stable generation of 15 megawatts (MW).

Of that figure, 10 MW came from distributed generation sites in the provincial capital —the same ones that were already generating power at dawn— and the other five were contributed by photovoltaic solar parks. The limitation in the use of solar energy, specialists explained, is due to safety concerns: these parks do not yet have storage systems that would allow them to stabilize frequency and power. Therefore, only a portion of their capacity is being used to contribute to the stability of the micro-system without jeopardizing its operation.

With this capacity, while the protocol established by the National Electric Union continued, health services were maintained in Las Tunas and Puerto Padre municipalities, as well as the water supply from the capital city's water sources. By late afternoon, the existing distributed generation sites in Puerto Padre came online to replace the energy supplied by the solar parks and maintain system stability.

One of the good news stories of the day came from the Lidio Ramón Pérez Power Plant in the municipality of Mayarí, Holguín. Unit 1 of the Felton plant suffered no damage after the National Electric System (SEN) outage. Its specialists carried out a comprehensive evaluation of all systems and maintained the technical conditions to begin startup as soon as they received external power at 110 kilovolts (kV) and 22 kV, an essential step before synchronization.

In contrast, no timeframe was specified for the reintegration of the 10 de Octubre Power Plant (Nuevitas) in Camagüey. The contribution of this power plant, along with “Felton” and “Renté, in Santiago de Cuba, was essential for eastern Cuba to establish its own microsystem and, eventually, connect to the national grid.

NOT WITHOUT SETBACKS

The recovery process was not without its obstacles. In the central part of the country, a fault in the 110 kV line in La Lima, in the municipality of Manicaragua, took the Hanabanilla hydroelectric plant offline and weakened the Villa Clara microsystem activated the previous day. This facility is key for frequency regulation while thermoelectric plants in the west and central regions are being brought online, a reminder of how fragile the infrastructure remains even as progress is made toward normalization.

In Matanzas, the Antonio Guiteras Power Plant progressed throughout Sunday in its startup process. After the boiler was filled, the process took between six and eight hours without any significant damage being reported, although the final word, as always in these cases, would be known during the ignition. The addition of "Guiteras" proved to be crucial in reaching the critical mass of generation capacity that enabled interconnection with the eastern region.

Amid the recovery process, the Ministry of Education announced that classes will resume this Monday, with the flexibility adopted in situations of total power outages. Students would be allowed to attend without their uniforms, and the double-shift schedule will be adjusted according to each school's capabilities. This measure, which aims to minimize disruption to the school calendar, reflects the desire to normalize daily life while the electrical system is still working to restore full stability. 

THREE BLACKOUTS IN LESS THAN A MONTH

To understand the magnitude of what happened, it's important to remember that Saturday's outage was the third this month. The first occurred on Wednesday, March 4; the second, on Monday, March 16; and the third, on Saturday, March 21. Each one triggered emergency protocols, tested the response capacity of the electrical crews, and subjected the population to days of uncertainty and hardship.

Authorities have consistently stated that these outages, which originated from the system's fragility, are due to a combination of structural and external factors. Among the former are aging infrastructure and a lack of sustained investment; among the latter, and decisively, the intensification of the economic, commercial, and financial blockade imposed by the United States government.

The shortage of diesel and fuel oil, a direct consequence of the restrictions that prevent Cuba from acquiring fuel on international markets, which limit access to distributed generation technologies, has been the main obstacle to accelerating recovery in each of these contingencies.

Under normal conditions, the banks of generators scattered throughout Cuba would have been able to supply part of the deficit, thereby shortening recovery times. However, the lack of fuel forces the country to rely almost exclusively on thermoelectric plants, whose startup processes are inherently slower and require stable conditions that remain fragile.

This is not a minor detail. It explains why, in the case of outages that do not cause damage, recovery takes days. This is why photovoltaic solar parks, despite having the full potential of the Caribbean sun at midday, can only contribute a fraction of their capacity to the system, due to a lack of storage systems, which the blockade also makes difficult to acquire.

A SYSTEM IN EXTREME FRAGILITY

The Electric Union, when announcing the full interconnection, warned that the National Electric System (SEN) remains in a state of extreme fragility. This is not rhetoric; it reflects the reality of a system that, although it has managed to rebuild, operates at the limit of its capacity, with minimal reserves and dependent on each functioning unit remaining stable.

The electrical authorities continue working throughout Monday morning to consolidate the interconnection, incorporate the remaining units, and strengthen the system's reserves. Meanwhile, the population is urged to exercise maximum rationality in their consumption, aware that every kilowatt saved contributes to the stability of a system that, for now, continues to walk a tightrope.