Antonio Guiteras, Cuba's largest single generating unit, stopped for the 20th time in 2026 on Sunday 26 July. Unión Eléctrica (UNE), which runs Cuba's national grid, forecast in its bulletin the following morning that 1,150 MW (megawatts) would be available against 3,250 MW of peak demand, a shortfall of 2,100 MW that would leave 64.6 per cent of the island simultaneously dark at the evening peak. The outturn came in at 64.04 per cent.1 The date is Día de la Rebeldía Nacional, the state holiday marking the 1953 assault on the Moncada barracks.
Seven thermal units stood offline alongside Guiteras, three broken down and four in scheduled maintenance: CTE Mariel unit 6, Felton unit 2 and CTE Rente unit 3 had failed, while CTE Santa Cruz unit 3, Nuevitas unit 5 and Rente units 5 and 6 were being worked on. UNE had forecast a 2,240 MW deficit for 16 July. Eleven days on the gap had barely closed, and the roster of components able to bring the system down had lengthened.
Cuba's 54 solar parks reached a record 758 MW at midday on 18 and 19 July, the first solar-capacity figure UNE has published. Solar produces nothing at 20:30, when household demand peaks and when the thermal fleet has to carry the whole island alone. Guiteras compounds that twice over. When UNE rebuilt the grid after the collapse of 1 to 3 August, it held Guiteras back until restart conditions were safe, along with Felton unit 1 and CTE Diez de Octubre unit 6. A stoppage therefore costs both the megawatts the unit would have generated and the spinning reserve it would have carried, meaning generation already synchronised and turning, able to absorb a sudden loss before the frequency falls away.
