In December 2025, the system-wide average supply increased to 20,233 MW, a 1.2% rise from November 2025. Meanwhile, electricity demand decreased to 13,440 MW, or 0.5% lower than the previous month. These conditions widened the overall system supply margin of 4,798 MW, up from 4,572 MW in November.
Despite the improvement in system-wide supply-demand balance, operating conditions varied across regions. Supply margins in the Visayas and Mindanao regions declined by 136 MW and 245 MW, respectively, primarily due to planned and forced outages of generating plants. These tighter regional conditions, combined with transmission constraints that limited access to lower-cost generation in Luzon, contributed to an increase in system-wide average energy price to 4.38 PHP/kWh, from 3.98 PHP/kWh in the previous billing month.
In Luzon, supply continued to increase while demand declined, similar to November 2025. These favorable conditions led to a reduction in the Luzon average market price to 2.98 PHP/kWh, compared to 3.52 PHP/kWh in the previous month.
In contrast, the Visayas and Mindanao grids experienced tighter operating conditions. In the Visayas, available supply increased by 106 MW compared to the previous billing month; however, demand rose more sharply by 181 MW, resulting in a net reduction in supply margin. In Mindanao, supply declined by 245 MW, alongside a 25 MW increase in demand, further tightening the supply-demand balance.
Under normal conditions, the Visayas grid is supported by power imports from Luzon through the Leyte–Luzon HVDC interconnection. However, during December, the HVDC link was either operating at its maximum Luzon‑to‑Visayas transfer limit of 250 MW or was offline due to maintenance for 69% of the billing period, significantly higher than the 34% constraint duration in November 2025 billing period. These prolonged limitations and restricted the transfer of lower-cost Luzon generation to the Visayas, contributing to price separation between Luzon and the Visayas-Mindanao grids.
Simultaneous outages of several generating units in the Visayas and Mindanao during the first half of December 2025 billing month further reduced baseload availability. In the Visayas, planned coal plant outages reached 238 MW, while forced outages across various technologies reached 110 MW. In Mindanao, coal and hydro units accounted for as high as 699 MW of unavailable capacity, alongside 257 MW of forced outages from other generating technologies. Under these tighter supply conditions, Battery Energy Storage Systems (BESS) and other higher-marginal-cost generation were dispatched more frequently during peak and constrained periods, resulting in regional market prices reaching PHP 7.86–8.53/kWh. Within the Visayas grid, congestion along the 230 kV Leyte–Cebu transmission corridor further limited internal power transfers, particularly affecting Leyte’s market trading nodes. This caused localized price separation and elevated nodal prices.
Both the Visayas and Mindanao also experienced reserve deficiencies. The Visayas recorded shortages in dispatchable reserves, while Mindanao experienced deficits in both regulating and dispatchable reserves. These conditions led to higher reserve market clearing prices and contributed to overall price pressure in the affected regions.
Toward the last week of the December 2025 billing period, generation availability in Visayas and Mindanao improved, and key transmission constraints eased. As operating conditions normalized, market prices in these regions declined, with prices ranging between PHP 3.08/kWh to PHP 3.21/kWh during this period.
The sustained high price conditions earlier in the month, driven by regional supply tightness, transmission constraints, and reserve scarcity, triggered the Secondary Price Cap (SPC) for 213 intervals in the Visayas and 216 intervals in Mindanao. As a result, the monthly average prices for December 2025 settled at PHP 7.22/kWh in Visayas and PHP 7.82/kWh in Mindanao.
Spot market volume rose in December 2025, accounting for 13.2% of total traded quantity from 12.3% in November. Correspondingly, the total spot trading amount rose from 13.13 billion PHP to 14.19 billion PHP.
In the reserve market, zonal prices decreased across most regions, except for Regulation Up in Luzon, Contingency and Dispatchable Reserves in Visayas, and Dispatchable Reserves in Mindanao. Overall, system-wide reserve market transactions decreased from PHP 4.10 billion in November 2025 to PHP 3.92 billion for December 2025.
