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The Mindanao power grid was placed under its first red alert of the year on Monday, August 10, as higher electricity demand tightened available supply and reduced power exports to the Visayas, which was also placed under red alert for several hours.
The National Grid Corporation of the Philippines (NGCP) said the Mindanao grid went under red alert from 3 to 4 p.m. and again from 5 to 8 p.m., coinciding with afternoon and evening peak demand periods. Yellow alerts were declared from 4 to 5 p.m. and from 8 to 10 p.m.
NGCP attributed the Mindanao alerts to an increase in forecast system demand. The higher requirement reduced the power available for export to the Visayas, adding pressure to a grid already dealing with supply constraints.
Alerts Lifted
By 9:20 p.m., NGCP had lifted the yellow alert over Mindanao. The grid then had 2,728 megawatts (MW) of available capacity against a peak demand of 2,426 MW, leaving a 302-MW margin.
A red alert is issued when available power is insufficient to meet consumer demand while also maintaining the transmission grid’s required regulating reserve. A yellow alert, meanwhile, indicates that the operating margin is insufficient to meet the grid’s contingency requirement, signaling limited reserves in case of an unexpected loss of generation.
The tight supply in Mindanao had a direct impact on the interconnected Visayas grid. NGCP placed the Visayas under red alert from 3 to 9 p.m., followed by a yellow alert until 10 p.m.
When the red alert was lifted at 9 p.m., the Visayas grid had 2,389 MW of available capacity against peak demand of 2,292 MW. The grid remained under yellow alert for another hour as reserves stayed constrained.
Impact On Visayas
NGCP earlier said prolonged forced outages involving some of the Visayas’ largest generating plants had weakened the region’s supply situation. Limited power imports from Mindanao further aggravated the shortage as higher demand in Mindanao reduced the electricity that could be transmitted to the Visayas.
During the alert period, the Visayas grid had available capacity of about 2,350 MW against peak demand of 2,276 MW, according to NGCP. A total of 909.9 MW of capacity was unavailable, with 26 generating plants shut down and another 13 operating at derated capacities.
The conditions demonstrate the vulnerability of the interconnected grids when demand rises while generating units remain unavailable or operate below their full capacity. The reduced availability of Mindanao exports left the Visayas with less support at a time when its own generation resources were already constrained.
NGCP said a red alert represents a more critical power supply condition because available generation cannot cover demand and the required regulating reserve. While a yellow alert does not necessarily mean that supply is already insufficient to meet consumer demand, it serves as a warning that the grid has limited reserves to respond to sudden generation losses or other system disturbances.
Although the alerts were lifted later in the evening, the episode underscored the narrow supply margins facing both grids during periods of high electricity consumption and continued generating plant outages.
Source:
https://www.sunstar.com.ph/davao/ngcp-lifts-red-alert-status-for-mindanao
https://bworldonline.com/the-nation/2026/08/10/769341/mindanao-grid-sees-first-red-alert/
https://business.inquirer.net/605119/red-yellow-alerts-persist-over-visayas-mindanao
