Philippines: Luzon, Visayas and Mindanao grids.
Status: operational.
Wholesale design: Five-minute, locational spot market. Since January 2024, energy and reserve schedules and prices are co-optimised and binding, with reserve transactions settled through WESM.
Operator
Independent Electricity Market Operator of the Philippines (IEMOP); National Grid Corporation of the Philippines as System Operator
Nominal frequency
60 Hz
Where energy trades
Where does energy trade in Wholesale Electricity Spot Market (WESM)?
Energy in Wholesale Electricity Spot Market (WESM) trades in 2 layers: five-minute spot energy and bilateral power supply agreements.
What a battery can sell
What ancillary services can a battery sell in Wholesale Electricity Spot Market (WESM)?
Wholesale Electricity Spot Market (WESM) has 3 ancillary-service products, across 3 families — regulation, contingency reserve and replacement reserve: Contingency Reserve, Dispatchable Reserve, Regulating Reserve. Response timing, direction and eligibility for each are in the cards below, as the official sources state them.
Facts below are stated as the official sources state them. A missing line means the
source does not state that value — never that the value is zero.
Regulation
Regulating Reserve REG_UP / REG_DOWN
operational
Continuously correct frequency and short-term energy imbalance in both directions.
Direction
raise; lower
Sustain
at least 5 min
Trigger / range
Governor-control-mode deadband not more than 0.15 Hz with speed droop not more than 5%, or AGC instruction.
Eligibility
Certified ancillary-service providers registered in WESM and conforming to monitoring standards.
Typical procurement
Requirements are dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 198 MW each up/down, Visayas 40 MW each, Mindanao 41 MW each; these are a dated sample, not a typical range.
No single response time applies: governor and AGC modes are measured differently. The facility must sustain provision for the entire five-minute dispatch interval.
Contingency reserve
Contingency Reserve CONTINGENCY
operational
Arrest and restore frequency after loss of a major generating unit or other contingency.
Direction
raise generation; lower load
Sustain
at least 5 min
Trigger / range
Governor-control deadband greater than 0.15 Hz and less than 0.30 Hz with speed droop not more than 5%, or System Operator AGC/manual dispatch instruction.
Eligibility
Certified reserve facilities conforming to reserve monitoring standards.
Typical procurement
Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 578 MW, Visayas 150 MW, Mindanao 117 MW.
No single response time applies: manual, governor and AGC modes are measured differently. Sustain is the relevant five-minute dispatch interval.
Replacement reserve
Dispatchable Reserve DISPATCHABLE
operational
Provide start-capable replacement reserve after contingencies or prolonged reserve deficiency.
Direction
raise generation
Expected within
15 minutes
Full activation
30 min
Trigger / range
System Operator start/dispatch instruction.
Eligibility
Certified offline or otherwise available reserve facilities meeting start/synchronisation requirements.
Typical procurement
Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 471 MW, Visayas 150 MW, Mindanao 116 MW.
Facility must be ready to synchronise within 15 minutes of instruction and deliver instructed MW within 15 minutes after synchronisation; no universal hold duration was found in the cited operating guideline.
Getting paid to exist
Does Wholesale Electricity Spot Market (WESM) have a capacity mechanism?
Adequacy is addressed through WESM energy/reserve prices, distribution-utility power supply agreements and competitive-selection processes, and NGCP ancillary-service procurement. These are not a central capacity product.
Auction held in 2025
No — No capacity auction for this market was found to have been held during 2025 in the sources reviewed.
No WESM capacity auction result exists for calendar 2025; renewable-energy auctions, utility PSA tenders and NGCP ancillary-service CSPs are different products.
Caveats
Technical notes
Co-optimised regulating-up, regulating-down, contingency and dispatchable reserve categories; contracted reserve quantities are netted in settlement.
Current as of · from the
Global Electricity Market Catalogue v1.2.0 (compiled to , CC BY 4.0). Facts belong to the linked official authorities;
verify the current rules before design or bidding decisions.
Questions
Common questions about Wholesale Electricity Spot Market (WESM)
Who operates Wholesale Electricity Spot Market (WESM)?
Wholesale Electricity Spot Market (WESM) covers Philippines: Luzon, Visayas and Mindanao grids and is operated by Independent Electricity Market Operator of the Philippines (IEMOP); National Grid Corporation of the Philippines as System Operator.
Was a qualifying capacity event held in Wholesale Electricity Spot Market (WESM) in 2025?
No. No WESM capacity market: no qualifying 2025 event is recorded. No capacity auction for this market was found to have been held during 2025 in the sources reviewed.
How is energy traded, priced and settled in Wholesale Electricity Spot Market (WESM)?
Wholesale Electricity Spot Market (WESM): Five-minute, locational spot market. Since January 2024, energy and reserve schedules and prices are co-optimised and binding, with reserve transactions settled through WESM.