Between 2021 and 2024, customers in Puerto Rico recorded an average of 27 hours of power interruptions per year, excluding exceptional events. By comparison, consumers on the U.S. mainland experienced about two hours of annual interruptions without major events. This difference highlights the scale of the challenges faced by the Puerto Rican grid.
Hurricanes and major events
In 2024, the average duration of outages reached 73 hours in Puerto Rico, of which 43 hours were directly attributed to extreme events such as hurricanes. In August of the same year, Hurricane Ernesto affected at least one million customers on the island. Two years earlier, in September 2022, Hurricane Fiona caused a total blackout, leaving all 1.5 million subscribers without electricity and bringing the annual average outage duration to nearly 200 hours.
Frequency of interruptions
Beyond duration, the frequency of outages also increased. In 2024, Puerto Rican customers experienced an average of 19 interruptions, including 14 without major events and 5 linked to natural disasters. By comparison, mainland U.S. consumers faced about 1.3 interruptions in 2023, with national data for 2024 not yet available. This contrast underlines the persistent gap between the two networks.
Vulnerabilities of the power system
Service interruptions in Puerto Rico are not solely due to extreme weather. The grid is weakened by transmission and distribution issues, often affected by vegetation management, as well as generation capacity constraints. The system relies heavily on ten power plants fueled by petroleum products, natural gas, or coal. The unplanned shutdown of even one of these units, or a fuel shortage, can reduce the reliability of the entire grid.
Reliability measures and statistical monitoring
Grid reliability is assessed through two indicators. The System Average Interruption Duration Index (SAIDI) measures the total annual average duration of non-momentary interruptions per customer, while the System Average Interruption Frequency Index (SAIFI) evaluates their frequency. Both measures distinguish between outages caused by major events and those occurring under normal operations. The U.S. Energy Information Administration (EIA) has collected these statistics since 2013 for the mainland United States and since 2021 for Puerto Rico. The preliminary version of its 2024 annual report was released in August, with the final version expected in October.
