MANILA, June 1 -- Continued forced outages at key coal-fired power plants prompted the National Grid Corporation of the Philippines (NGCP) to place the Visayas grid under yellow alert again on Monday from 3 p.m. to 9 p.m.

In an advisory, the NGCP said the Visayas grid's available capacity stood at 2,579 megawatts (MW), while peak demand was projected to reach 2,488 MW.

A yellow alert is issued when the operating margin is insufficient to meet the grid's contingency reserve requirement.

The latest alert comes as a total of 11 power plants have remained on forced outage since May.

Among the affected facilities are Units 1 and 2 of Therma Visayas Inc., a generating unit of Panay Energy Development Corp., and Unit 2 of Kepco SPC Power Co...