Luzon, Visayas Face Tight Power Supply in June 2025, Study Says

By Joseph Bernard A. Marzan and Rjay Zuriaga Castor

QUEZON CITY — Luzon and Visayas may experience tight power supply conditions in June 2025, while Mindanao is projected to maintain stable reserves throughout the second quarter, according to the latest Philippine Power Outlook report.

The report, released by the Institute for Climate and Sustainable Cities (ICSC), analyzes the operating margins across the country’s three main power grids using data from the National Grid Corporation of the Philippines (NGCP) and the Department of Energy (DOE).

The data are based on the 2025 Weekly Demand, Supply, and Operating Margin Profile published in December 2024.

Operating margin refers to the difference between available generating capacity and peak demand, calculated by subtracting the forecasted peak demand, High Voltage Direct Current (HVDC) exports, and forced outage allowance from the total available and committed capacities.

This marks ICSC’s fourth annual power outlook since the initiative launched in 2022.

Similar to previous years, the group warned of second-quarter power supply risks, particularly for Luzon and Visayas.

For Luzon, normal reserve levels are expected in April, yellow alerts in May, and potential red alerts in June.

Yellow alerts are issued when reserves fall below the required contingency level, while red alerts signal a deficiency in the regulating reserve, indicating possible power interruptions.

From March 31 to June 1, Luzon is projected to export 250 megawatts (MW) to the Visayas grid via the HVDC interconnection, but will likely restrict exports during June 2 to 8 due to reduced coal generation of around 842 MW, the report said.

“The Luzon grid is expected to face its tightest period in Week 23 due to lower coal generation, making red alerts possible,” ICSC said in a press release.

The think tank also pointed to the March 5 yellow alert issued by NGCP over Luzon, when seven baseload coal plants were on outage, taking 2,495 MW offline.

“Elevated summer demand contributes to the strain, but forced outages and derated operations of baseload plants severely disrupt supply,” said Jephraim Manansala, ICSC chief data scientist and co-author of the report.

Meanwhile, the Visayas grid is expected to have normal reserves for most of the second quarter but may face yellow alerts in June due to restricted power imports from Luzon.

Visayas relies heavily on electricity imports from Luzon and Mindanao and has unique transmission constraints due to its configuration of five interconnected island grids.

“Transmission capacity varies between islands, which creates bottlenecks when demand spikes in a specific area,” the report noted.

The ICSC projected a negative net operating margin for Visayas from April to June, meaning local generation alone will not meet peak demand.

To maintain sufficient capacity, the Visayas grid will depend on 450 MW from Mindanao and 250 MW from Luzon through HVDC links.

“Maintaining adequate reserve levels in Visayas heavily depends on HVDC imports,” the report emphasized.

The think tank said more granular monitoring of localized grid conditions is needed to prevent system-wide blackouts.

It cited the Panay Island blackout in January 2024 as a preventable event had more detailed monitoring been in place.

“By focusing on localized data, grid operators can respond more effectively to emerging challenges,” Manansala said.

As of December 2024, six committed power projects with a total capacity of 286.35 MW are scheduled to begin operations in the Visayas during the first half of 2025, most of which are renewable energy sources.

The ICSC stressed the importance of timely commissioning of these projects and strict adherence to the Grid Operating and Maintenance Program (GOMP) to prevent further outages.

It also highlighted regional differences, such as the surplus of solar power in Negros Island, which remains underutilized due to transmission constraints.

In contrast, Mindanao is projected to maintain sufficient reserves despite exporting 450 MW to Visayas.

“Mindanao can reduce its exports if necessary to ensure grid reliability within its own network,” the ICSC said.

The group called for stronger compliance among existing power plants with maintenance schedules and operational protocols to ensure long-term grid stability nationwide.