Power supply in the Visayas is coming under mounting strain, with the grid logging 123 yellow and red alerts so far this year as prolonged plant outages leave consumers exposed to rotating power interruptions.

The National Grid Corp. of the Philippines (NGCP) said the Visayas recorded 93 yellow alerts and 30 red alerts from January to 3 September.

The strain intensified Thursday as NGCP placed the grid under red alert from 1 p.m. to 10 p.m., with available capacity of 2,187 megawatts (MW) falling 388 MW short of projected peak demand of 2,575 MW.

With supply unable to meet demand, NGCP warned that Manual Load Dropping (MLD), or rotational power interruptions, may be implemented in several areas to keep the grid stable.

“The implementation of Manual Load Dropping (MLD) is due to limited generation and zero import power from the Mindanao grid,” NGCP said.

About 792 MW of capacity was unavailable in the Visayas, with several generating units on forced outage and 16 plants operating at reduced capacity.

NGCP cited the unavailability of major coal plants TVI Unit 1 and PEDC Unit 3, compounded by limited or unavailable imports from Mindanao, as key factors behind the tight supply.

Mindanao is also grappling with thinning reserves, having recorded 10 yellow alerts and three red alerts since January.

The grid was placed under red alert from noon to 9 p.m. Thursday as available capacity of 2,480 MW fell below projected peak demand of 2,546 MW.

Around 841.6 MW of capacity was unavailable in Mindanao, with several plants on forced outage and seven others operating at reduced capacity. NGCP cited the unavailability of major coal plants GNPK Units 1 and 2 and TSI Unit 2, among the factors squeezing supply.

Combined, the Visayas and Mindanao grids had nearly 1,634 MW of unavailable generating capacity.