Electricity prices in the Wholesale Electricity Spot Market (WESM) declined significantly in September 2025, driven by a slight increase in supply and a notable decrease in demand, data from the Independent Electricity Market Operator of the Philippines (IEMOP) showed.

The system-wide average spot price fell by 33.8% to PHP 3.04 per kilowatt-hour (kWh) from PHP 4.59/kWh in August, marking the lowest level in seven months. Average supply rose by 0.5% to 20,712 megawatts (MW) from 20,611 MW, while demand dropped by 2.9% to 13,640 MW from 14,052 MW. This widened the average supply margin to 5,194 MW from 4,578 MW the previous month.

The downward trend was observed across the country’s major grids. In Luzon, which accounts for the bulk of demand, the average price decreased by 31.7% to PHP 2.57/kWh from PHP 3.76/kWh. Supply edged up 0.2% to 14,681 MW, while demand eased 2.9% to 9,595 MW.

In the Visayas, prices saw a steeper drop of 37.1% to PHP 4.02/kWh from PHP 6.40/kWh, with supply increasing 1.5% to 2,440 MW and demand falling 4% to 1,945 MW. Similarly, Mindanao’s average price declined by 37.1% to PHP 4.19/kWh from PHP 6.66/kWh, as supply grew 0.9% to 3,592 MW and demand slipped 2.1% to 2,100 MW.

IEMOP attributed the stable operations to the absence of major plant outages during the billing period from August 26 to September 25. However, it noted that an earthquake in the Visayas on September 30 led to the tripping of several transmission lines and generators, which will be reflected in the October billing period.

The Effective Spot Settlement Price (ESSP), which represents the average price paid by customers exposed to the spot market, averaged PHP 3.28/kWh, down from PHP 5.56/kWh in August. Spot market transactions accounted for 13.7% of total energy requirements, lower than the 15.5% in the prior month. Total trading value in the spot market decreased to PHP 8.84 billion from P15.32 billion.

In terms of generation mix, renewable energy sources contributed 26% to the total output. Coal’s share rose to 55.1% from 50.6%, hydro increased to 13.5% from 12.6%, while natural gas fell to 17% from 22%. Oil-based generation dropped to 0.5% from 0.9%, solar to 3.7% from 4%, and geothermal to 7.6% from 7.8%.

Registered capacities in the WESM climbed by 214.3 MW to a total of 29,889 MW.

In the reserve market, total transactions amounted to PHP 4.68 billion, down from PHP 5 billion in August. Reserve prices varied by type and region, with increases noted in regulation reserves for Luzon and Mindanao. In Luzon, regulation reserves averaged PHP 3-9/kWh, contingency PHP 0.9-1.2/kWh, and dispatchable PHP 0.4-1.9/kWh. 

The Visayas had higher regulation prices at PHP 6-25/kWh, contingency at PHP 3.8-5.5/kWh, and dispatchable at PHP 7-9/kWh. Mindanao recorded the highest regulation costs at PHP 23-25/kWh, with contingency at PHP 0.3-3.3/kWh and dispatchable at PHP 0.9/kWh.

Overall, IEMOP said the lower spot prices and reduced transactions align with decreased market exposure and stable system conditions.

What are your thoughts on WESM price movements in September? Join the discussion below. 

Follow Power Philippines on Facebook and LinkedIn or join our Viber community for more updates.