MANILA, Philippines — Power supply remains under pressure in the Visayas and Mindanao, with repeated red and yellow alerts raising fresh concerns over the reliability of electricity as several major power plants remain offline or operate below full capacity.
The latest National Grid Corporation of the Philippines (NGCP) advisories show that the problem has persisted into September, with the two grids repeatedly placed under alert as available generation struggles to maintain sufficient reserves.
On September 10, the Visayas grid was placed under red alert from 2 p.m. to 9 p.m., while yellow alerts covered the periods before and after the red-alert window. NGCP said the Visayas had only about 2,205 megawatts (MW) of available capacity against projected peak demand of 2,460 MW.
The situation was driven largely by the continued unavailability of major coal-fired generating units, including Therma Visayas Inc. Units 1 and 2 and Panay Energy Development Corp. Unit 3. Reduced electricity imports from Mindanao also further tightened the Visayas supply picture.
The scale of the capacity problem is significant. NGCP said 10 Visayas power plants had been on forced outage during September, while 22 others had been unavailable at various points over the previous five years. Another 16 plants were operating at reduced capacity, resulting in an estimated 979.9 MW of unavailable capacity.
Mindanao faces its own supply squeeze
Mindanao has also experienced repeated alerts, although its situation has varied from day to day.
On September 10, the Mindanao grid was placed under yellow alert during two periods, with available capacity estimated at 2,724 MW against projected peak demand of 2,552 MW. NGCP identified the unavailability of GNPower Kauswagan Units 2 and 3 among the factors behind the alert.
Just a day earlier, Mindanao faced an eight-hour yellow-alert period, while the Visayas endured a nine-hour red alert. At that time, NGCP reported approximately 2,731 MW of available capacity in Mindanao against peak demand of 2,600 MW.
The recurring alerts show how little room the grids have to absorb additional outages or unexpected increases in electricity demand.
Why are red and yellow alerts important?
A yellow alert does not automatically mean a blackout is occurring. It means the grid’s operating margin has fallen below the level required to cover a contingency, such as the sudden loss of a generating unit.
A red alert is more serious. NGCP declares it when available supply is insufficient to meet consumer demand as well as the transmission grid’s regulating requirements.
That distinction matters because prolonged or repeated red alerts can increase the risk of controlled power interruptions if supply conditions deteriorate further.
The pressure has already been visible throughout September. On September 4, both Visayas and Mindanao were placed under red alert at different periods, with Visayas having 2,233 MW available against 2,504 MW of peak demand, while Mindanao had 2,549 MW against 2,592 MW of expected peak demand.
Earlier, on September 3, NGCP reported only 2,187 MW of available capacity in the Visayas against projected peak demand of 2,575 MW, while Mindanao also faced a prolonged red-alert period.
The bigger problem: repeated plant outages
The latest alerts point to a broader reliability challenge rather than a single isolated breakdown.
Several large coal-fired plants have remained unavailable, while other generating facilities are operating at reduced capacity. In the Visayas, NGCP has repeatedly cited the outages of TVI and PEDC units and limited imports from Mindanao as major contributors to the tight supply situation.
Mindanao has faced a similar problem, with forced outages affecting major generating facilities such as GNPower Kauswagan and Therma South.
The situation has also coincided with periods of strong electricity demand, leaving less reserve capacity available when plants unexpectedly go offline.
What this means for consumers
For households and businesses across the Visayas and Mindanao, the repeated alerts are more than technical grid warnings.
If available supply falls further or additional generating units unexpectedly shut down, power distributors could face the possibility of implementing manual load dropping or controlled interruptions to protect the wider grid.
That does not mean every red or yellow alert will result in a blackout. But the repeated declarations highlight how vulnerable the system becomes when multiple large generating units are simultaneously unavailable.
The immediate challenge for grid operators is therefore to keep enough generating capacity online while restoring unavailable plants and maintaining adequate reserves.
The longer-term question is harder: Can the country’s power infrastructure add enough reliable generation and transmission capacity to keep pace with rising electricity demand?
For consumers in the Visayas and Mindanao, that question is becoming increasingly urgent as red and yellow alerts move from occasional warnings to a recurring feature of the power landscape.
The lights may still be on — but the shrinking margin between supply and demand is sending a warning that the country’s power system cannot afford to ignore.
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