The country's power supply was put at risk after a red alert status was raised in the Visayas while Luzon continued to suffer from a thin electricity supply.
The Department of Energy (DOE) said a red alert was raised in the Visayas grid from 5 to 6 p.m. and a yellow alert from 2 to 5 p.m. and from 6 to 9 p.m.
Back in the country's largest island of Luzon, a yellow alert was up from 1 p.m. to 4 p.m. and from 5 p.m. to 7 p.m.
The DOE said in the Visayas, power plants on forced outage were Unit 1 of Power Barge 101, Units 2 and 3 of the Naga diesel power plant, and Unit 3 of the Panay power plant.
'Those running on derated capacities are TPC Thermal, EDC/Leyte 2, and PGPP2,' it added.
In Luzon, power plants that were on unscheduled shutdown included Unit 2 of the Calaca power plant, Unit 3 of the Masinloc power plant, Unit 1 of the Mariveles power plant, and Unit 2 of the Dinginin power plant while those running on limited capacities were Units 1 and 2 of the Masinloc power plant and Unit 1 of the Sual power plant.
Outages cause probed
Earlier, the Energy Regulatory Commission (ERC) said it would investigate the issuance of yellow alerts in Luzon which began last week.
'We investigate the outages to determine causes and, if needed, issue show-cause orders to allow affected parties to explain,' said ERC chair Monalisa Dimalanta had said in a message to the Inquirer.
'Penalties are issued if explanation is not valid, but more importantly we see how causes can be addressed to avoid further outages,' Dimalanta added.
The yellow alert status means very small power reserves are available to meet any spike in demand, while the red alert status denotes a supply deficiency exists which can result in power interruptions.
'The red/yellow alerts that occurred last Monday are under evaluation. We expect updated report from our team next week. For this set of outages today, report will be submitted to the Commission in two weeks,' Dimalanta said last week.