Puerto Rico’s electric system is confronting a worsening reliability crisis, with LUMA Energy reporting that the island continues to face a structural generation shortfall of between 700 and 850 megawatts.
In a filing submitted recently to the Puerto Rico Energy Bureau and obtained by Caribbean Business, LUMA describes a grid under mounting stress from extreme heat, aging thermal units, deferred maintenance and rising demand, concluding that Puerto Rico still urgently needs hundreds of megawatts of temporary generation to prevent widespread outages during the highest-demand months.
LUMA’s conclusion is unequivocal in stating that the underlying supply deficit has not changed. “Puerto Rico continues to face a persistent generation supply deficit of 700-850 MW, driven by an aging and degraded thermal fleet, frequent forced outages, deferred maintenance, and rising peak demand fueled by extreme heat,” the private operator said.
The most consequential portion of the filing is LUMA’s sensitivity analysis, which models how the grid would perform under a range of adverse conditions.
Under the base case, Puerto Rico faces eight days of load shedding between May and October. But even slight deviations from expected conditions produce significantly worse outcomes.
A five percent increase in load nearly doubles the number of expected load-shedding days. A ten percent increase pushes the total to 26 days. The loss of another baseload unit raises the number to 27 days. A combined scenario involving a ten percent load increase and another baseload outage produces 47 days of load shedding and 230 hours of outages.
LUMA notes that actual events this summer already resemble the worst-case scenarios, with real-world conditions matching the sensitivity cases involving higher load and additional baseload outages.
The modeling also evaluates how much temporary generation would be required to bring Puerto Rico’s reliability in line with U.S. industry standards.
Needed: significant new generation
Many North American utilities plan their systems to achieve one loss-of-load event every ten years, a benchmark known as LOLE 0.1. Puerto Rico’s actual performance in fiscal year 2026 was 17 shortfall events, which LUMA notes is “about 170 times worse than benchmark levels set by the North American electric utility industry.”
According to the filing, adding 800 megawatts of firm temporary generation would bring Puerto Rico close to the LOLE 0.1 standard. Smaller additions produce partial improvements: 200 megawatts significantly reduces expected outages, 400 megawatts reduces them further, and 800 megawatts nearly eliminates load shedding altogether.
These results align with LUMA’s earlier conclusion that Puerto Rico’s structural deficit falls between 700 and 850 megawatts, a range that has remained consistent across four consecutive annual resource adequacy studies.
The report’s final conclusion is that Puerto Rico’s electric system remains structurally fragile, and the summer 2026 experience demonstrates that reliability improvements cannot occur without significant new generation.
“The system remains vulnerable, principally due to multiple planned outages that are continuously being delayed or deferred,” LUMA writes.
A summer that already looks like the worst case
The summer of 2026 has already demonstrated how fragile the system has become. Beginning in July, a surge in unit trips and forced outages produced 15 manual load-shedding events in July and August alone, nearly matching the total number of events recorded in all of fiscal year 2025.
These interruptions occurred primarily during evening peak hours, when reserve margins collapse and rooftop solar cannot contribute. LUMA warns that if current conditions continue, the number of load-shedding events could approach the levels seen in 2023 and 2024, when Puerto Rico experienced 25 and 33 events respectively.
With 16 load-shedding events already recorded by August, LUMA warns that Puerto Rico is already on track to match or exceed the outage levels of 2023 and 2024 unless temporary generation is deployed.
The operator attributes the spike in outages to a combination of extreme heat, higher-than-forecast demand and deteriorating unit performance. Peak demand reached approximately 3,234 megawatts in August, the highest level in four years and well above LUMA’s summer forecast. Cooling degree days, a key measure of temperature-driven load, were among the highest in a decade, pushing demand beyond forecast levels and further straining the system.
“Higher than expected temperatures have elevated demand above forecast levels,” the report states.
Erosion of reserve margins
The updated assessment was ordered by regulators seeking clarity on whether the temporary generation initiative launched in 2025, which contemplated up to 800 megawatts of mobile units, barges and replacement equipment, remains necessary.
PREB sought the information after the government cancelled a contract awarded to a consortium headed by Power Expectations to provide 400 megawatts of temporary energy.
Thermal fleet instability remains the central weakness in Puerto Rico’s generation portfolio. Although the island has more than 6,500 megawatts of installed generation capacity, only about 4,100 megawatts are actually available, and real-time availability often falls closer to 3,200 megawatts once forced outages and planned maintenance are factored in.
The catastrophic failure of Aguirre Unit 1 in February 2025 continues to weigh heavily on system reliability, removing one of the island’s largest baseload units from service through at least the end of 2026.
LUMA notes that even modest decreases in generation availability rapidly erode reserve margins and increase stress on remaining units, ultimately triggering load-shedding events.
To avoid immediate supply shortfalls, LUMA and Genera deferred planned maintenance on multiple units throughout the spring and summer. While this temporarily increased generation availability, the report warns that the strategy will likely lead to higher forced outage rates in the coming months and compress the already limited winter maintenance window.
LUMA cautions that this dynamic is expected to heighten unit unavailability and further erode operating reserve margins, adding stress to an already constrained system.
