The Independent Electricity Market Operator of the Philippines (IEMOP) said tighter supply margins, rising electricity demand, and widespread plant outages pushed Wholesale Electricity Spot Market (WESM) prices higher during the April 2026 billing period.

During a media briefing held Wednesday, IEMOP reported that the system-wide average WESM price rose 30.6% to PHP 5.63 per kilowatt-hour (kWh), up from PHP 4.31/kWh in March.

The increase came as average demand grew faster than supply during the billing period covering March 26 to April 25. 

According to IEMOP data, average system demand increased 7.6% month-on-month to 14,404 megawatts (MW), while average supply rose only 4.6% to 20,819 MW. This narrowed the system-wide supply margin to 4,427 MW from 4,654 MW in the previous billing period.

Supply margins across Luzon, Visayas, and Mindanao also declined due to higher outage levels and changes in high-voltage direct current (HVDC) power flows between the grids. Luzon’s supply margin fell by 173 MW, while Visayas and Mindanao margins declined by 52 MW and 1 MW, respectively.

IEMOP said the tighter supply-demand conditions contributed to the increase in market prices.

The Effective Spot Settlement Price (ESSP), or the actual settlement price used in the spot market, also increased 11.3% to PHP 5.32/kWh. Meanwhile, total spot market trading amount rose sharply from PHP 13.56 billion in March to PHP 19.49 billion in April as spot market volumes increased.

WESM is the country’s electricity spot market where power generators and distribution utilities buy and sell electricity in real time.

Despite the increase in market prices, IEMOP said the implementation of Modified Administered Prices (MAP) helped temper sharper price spikes during the ongoing State of National Energy Emergency.

The Energy Regulatory Commission (ERC) earlier suspended normal WESM operations effective March 26 as part of government fuel conservation and supply stabilization measures. Under the temporary MAP setup, coal prices were capped at PHP 6.00/kWh, while all negative administered prices were set at zero.

“The application of Modified Administered Prices helped temper the potential impact of rising fuel costs to the electricity market prices, mitigating price volatility in the WESM,” said Engr. Isidro E. Cacho Jr., IEMOP Vice President for Trading Operations.

IEMOP also reported significant generating unit outages across all major grids during the billing period.

In Luzon, forced outages reached 21,404.3 MW, mostly involving coal and natural gas plants. The Visayas grid recorded 5,610.45 MW of forced outages, largely from solar and geothermal facilities, while Mindanao posted 3,556.05 MW of forced outages across several technologies including hydro, coal, and battery systems.

Despite the outages, IEMOP said average supply remained sufficient throughout the period.

Coal remained the dominant power source in the country’s generation mix, accounting for 58.4% of total generation during the billing period, followed by natural gas at 17%. Renewable energy accounted for 23% of the generation mix. Among renewable sources, solar generation increased from 6.5% to 7.1%, while geothermal rose from 7.6% to 8.2%. Hydropower and wind generation shares, however, declined during the period.

Meanwhile, the ERC officially lifted the market suspension and restored normal WESM clearing and settlement operations effective May 1, 2026.

As electricity demand continues to rise during the summer months, will tighter supply margins and persistent plant outages place further upward pressure on spot market prices?

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