THE National Grid Corp. of the Philippines (NGCP) placed the Luzon and Visayas grids under yellow alert on Tuesday, triggered by a thinning in the supply-demand balance.

In an advisory, the NGCP said yellow alerts were declared for Luzon between 1 p.m. and 5 p.m. and 8 p.m. and 10 p.m.

Available capacity was 14,963 megawatts (MW) while peak demand hit 13,871 MW.

The grid operator said that five power plants have been on forced outage since 2023. Four power plants were inoperable between January and March and six between April and May.

Four power plants are running on derated capacity.

As a result of forced outages and capacity limitations, 1,532.1 MW were unavailable to the grid.

A yellow alert is issued when the operating margin is insufficient to meet the transmission grid’s contingency requirement. A red alert is imposed when the supply-demand balance deteriorates further.

The Visayas grid was under yellow alert between 1 p.m. and 4 p.m. and from 6 p.m. to 9 p.m.

Peak demand was 2,646 MW, against available capacity of 2,877 MW.

According to the NGCP, one plant on the Visayas grid has been on forced outage since 2022; two since 2023; two between January and March; and 16 between April and May.

Four are running on derated capacity. Overall, a 550.1 MW were unavailable to the grid. — Sheldeen Joy Talavera