Wholesale Electricity Spot Market (WESM)

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 table below; a product's full record lists the official sources behind it.

Every value below comes from the official sources listed in that product's full record. Most products cite more than one, and the published sources do not say which of them states each individual value, so the binding is to the product's record rather than to a single document. A missing line means the source does not state that value — never that the value is zero.

Scroll the table sideways for the rest of the columns →

3 ancillary-service products in Wholesale Electricity Spot Market (WESM), grouped into 3 families. Each row runs left to right through one product's life: how it activates, how quickly it has to respond, how long it has to keep delivering, and how it is bought.
Service How it activates Response Sustained delivery Procurement
Regulation
Regulating Reserve REG_UP / REG_DOWN raise; lower operational Response type pre-fault governor control or AGC Trigger Governor-control-mode deadband not more than 0.15 Hz with speed droop not more than 5%, or AGC instruction. Minimum obligation at least 5 min Reported, not a current requirement 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. 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. Through co-optimised WESM reserve market with System Operator as single buyer Bought day-ahead offers with five-minute co-optimised scheduling and rebids under WESM rules How it settles Binding reserve schedule and market price; contracted reserve is netted and residual spot quantity settles at reserve market price.
Full record for Regulating Reserve — document bound, page for these figures not recorded
What it is for

Continuously correct frequency and short-term energy imbalance in both directions.

In force from

26 September 2024

Who can provide it

Certified ancillary-service providers registered in WESM and conforming to monitoring standards.

Notes from the source

No single response time applies: governor and AGC modes are measured differently. The facility must sustain provision for the entire five-minute dispatch interval.

Checkpoint recap

Minimum sustained 5 min

What the source does not state

The source states a minimum delivery period and a procurement volume in its own words. It does not state a response time or a maximum duration.

Sources
Contingency reserve
Contingency Reserve CONTINGENCY raise generation; lower load operational Response type post-fault governor AGC or manual instruction Trigger 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. Minimum obligation at least 5 min As stated Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 578 MW, Visayas 150 MW, Mindanao 117 MW. Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 578 MW, Visayas 150 MW, Mindanao 117 MW. Through co-optimised WESM reserve market Bought five-minute co-optimised scheduling How it settles Binding reserve schedule and price with contracted-reserve netting.
Full record for Contingency Reserve — document bound, page for these figures not recorded
What it is for

Arrest and restore frequency after loss of a major generating unit or other contingency.

In force from

26 September 2024

Who can provide it

Certified reserve facilities conforming to reserve monitoring standards.

Notes from the source

No single response time applies: manual, governor and AGC modes are measured differently. Sustain is the relevant five-minute dispatch interval.

Checkpoint recap

Minimum sustained 5 min

What the source does not state

The source states a minimum delivery period and a procurement volume in its own words. It does not state a response time or a maximum duration.

Sources
Replacement reserve
Dispatchable Reserve DISPATCHABLE raise generation operational Response type post-fault centrally instructed start Trigger System Operator start/dispatch instruction. Expected within 15 min Full activation 30 min As stated Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 471 MW, Visayas 150 MW, Mindanao 116 MW. Dynamic by grid. Example official weekly averages for 8-14 September 2025: Luzon 471 MW, Visayas 150 MW, Mindanao 116 MW. Through co-optimised WESM reserve market Bought five-minute co-optimised scheduling with day-ahead contracted offers How it settles Binding reserve schedule and price with contracted-reserve netting.
Full record for Dispatchable Reserve — document bound, page for these figures not recorded
What it is for

Provide start-capable replacement reserve after contingencies or prolonged reserve deficiency.

In force from

26 September 2024

Who can provide it

Certified offline or otherwise available reserve facilities meeting start/synchronisation requirements.

Notes from the source

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.

Checkpoint recap

Expected within 15 min · Full activation 30 min

What the source does not state

The source states the response deadline and a procurement volume in its own words. It does not state how long delivery has to be sustained.

Sources
Getting paid to exist

Does Wholesale Electricity Spot Market (WESM) have a capacity mechanism?

No. Wholesale Electricity Spot Market (WESM)'s capacity/adequacy arrangement: No WESM capacity market.

No WESM capacity market

none operational

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.

Where this comes from

Official sources

Rules

Service specification

Market explainer

Capacity-mechanism explainer

Current as of · from the Global Electricity Market Catalogue v1.2.0 (compiled to , CC BY 4.0, rendered here with wording edited for readability). 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.
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The markets index holds the full set. For what the grid demands of a battery here, see the grid-code ride-through atlas.

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