SPP

Central United States.

Wholesale design: nodal Integrated Marketplace with day-ahead, reliability-unit-commitment, and real-time balancing markets; decentralized resource adequacy.

Operator
Southwest Power Pool
Nominal frequency
60 Hz
Where energy trades

Where does energy trade in SPP?

Energy in SPP trades in 2 layers: Day-Ahead Market and Real-Time Balancing Market. Participation in Real-Time Balancing Market is mandatory. Scheduling and settlement, where the cited sources give them, are in the table below.

Layer Scheduling Settlement
Day-Ahead Market hourly locational marginal pricing and market-clearing prices for operating reserve
Real-Time Balancing Market (mandatory) five-minute dispatch real-time locational marginal pricing and operating-reserve market-clearing prices
What a battery can sell

What ancillary services can a battery sell in SPP?

SPP has 8 ancillary-service products, across 4 families — regulation, contingency reserve, ramping reserve and replacement reserve: Ramp Capability Down, Ramp Capability Up, Regulation-Down, Regulation-Up, Spinning Reserve, Supplemental Reserve, Uncertainty Reserve Down, Uncertainty Reserve Up. 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 →

8 ancillary-service products in SPP, grouped into 4 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
Regulation-Down Response type pre-contingency continuous Trigger continuous regulation deployment within the cleared regulation range Dispatched by automatic generation control, with setpoint signals transmitted every four seconds Through day-ahead; real-time Pricing design regulation capacity and mileage compensation
Full record for Regulation-Down — document bound, page for these figures not recorded
What it is for

Correct downward area-control error through automatic dispatch around a resource base point.

What the source does not state

It does not state a response time or how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Regulation-Up Response type pre-contingency continuous Trigger continuous regulation deployment within the cleared regulation range Dispatched by automatic generation control, with setpoint signals transmitted every four seconds Through day-ahead; real-time Pricing design regulation capacity and mileage compensation
Full record for Regulation-Up — document bound, page for these figures not recorded
What it is for

Correct upward area-control error through automatic dispatch around a resource base point.

What the source does not state

It does not state a response time or how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Contingency reserve
Spinning Reserve Response type post-contingency Trigger online capacity available within the contingency-reserve deployment period Dispatched by SPP contingency-reserve deployment instruction Expected within 10 min Through day-ahead; real-time Pricing design operating-reserve market-clearing price
Full record for Spinning Reserve — document bound, page for these figures not recorded
What it is for

Provide synchronized contingency reserve.

Checkpoint recap

Expected within 10 min

What the source does not state

The source states the response deadline. It does not state how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Uncertainty Reserve Down Response type pre-contingency flexibility Trigger one-hour uncertainty horizon; eligible online resources Dispatched by market commitment and dispatch positioning No deadline established The one-hour value defined for this product is a procurement and capability horizon, not a universal instruction-to-full-response deadline. Through day-ahead; reliability unit commitment; real-time Pricing design market compensation under Integrated Marketplace rules
Full record for Uncertainty Reserve Down — document bound, page for these figures not recorded
What it is for

Hold downward capability for forecast uncertainty over a one-hour look-ahead.

What the source does not state

It does not state a response time or how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Uncertainty Reserve Up Response type pre-contingency flexibility Trigger one-hour uncertainty horizon; eligible online and qualified offline resources Dispatched by market commitment and dispatch positioning No deadline established The one-hour value defined for this product is a procurement and capability horizon, not a universal instruction-to-full-response deadline. Through day-ahead; reliability unit commitment; real-time Pricing design market compensation under Integrated Marketplace rules
Full record for Uncertainty Reserve Up — document bound, page for these figures not recorded
What it is for

Hold upward capability for forecast uncertainty over a one-hour look-ahead.

What the source does not state

It does not state a response time or how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Ramping reserve
Ramp Capability Down Response type pre-contingency flexibility Trigger ten-minute future dispatch horizon; only online resources are eligible Dispatched by co-optimized positioning in the real-time market Expected within 10 min Through real-time Pricing design no submitted offer; compensation is based on calculated opportunity cost under market rules
Full record for Ramp Capability Down — document bound, page for these figures not recorded
What it is for

Preserve downward ramp capability for expected net-load movement beyond the immediate dispatch interval.

Checkpoint recap

Expected within 10 min

What the source does not state

The source states the response deadline. It does not state how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Ramp Capability Up Response type pre-contingency flexibility Trigger ten-minute future dispatch horizon; only online resources are eligible Dispatched by co-optimized positioning in the real-time market Expected within 10 min Through real-time Pricing design no submitted offer; compensation is based on calculated opportunity cost under market rules
Full record for Ramp Capability Up — document bound, page for these figures not recorded
What it is for

Preserve upward ramp capability for expected net-load movement beyond the immediate dispatch interval.

Checkpoint recap

Expected within 10 min

What the source does not state

The source states the response deadline. It does not state how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Replacement reserve
Supplemental Reserve Response type post-contingency Trigger qualified capability available within ten minutes; may include quick-start resources Dispatched by SPP contingency-reserve deployment instruction Expected within 10 min Through day-ahead; real-time Pricing design operating-reserve market-clearing price
Full record for Supplemental Reserve — document bound, page for these figures not recorded
What it is for

Provide additional ten-minute contingency reserve from qualified online or quick-start resources.

Checkpoint recap

Expected within 10 min

What the source does not state

The source states the response deadline. It does not state how long delivery has to be sustained, and the volume is either set per auction or not published as a standing figure — the source does not say which.

Sources
Getting paid to exist

Does SPP have a capacity mechanism?

No central capacity market. SPP has 1 capacity/adequacy arrangement — Resource Adequacy Requirement — and it works differently.

Resource Adequacy Requirement

Load-responsible entities self-supply or arrange capacity bilaterally; SPP applies deficiency-payment and compliance provisions rather than clearing a centralized capacity auction. A winter-season requirement began in 2025.

Unit of obligation
accredited capacity sufficient to meet each load-responsible entity's forecast peak demand plus planning reserve margin
Auction held in 2025
No — No capacity auction for this market was found to have been held during 2025 in the sources reviewed.
Where this comes from

Official sources

Rules

Service specification

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 SPP

Who operates SPP?
Southwest Power Pool operates SPP, covering Central United States.
Was a qualifying capacity event held in SPP in 2025?
No. Resource Adequacy Requirement: 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 SPP?
SPP: nodal Integrated Marketplace with day-ahead, reliability-unit-commitment, and real-time balancing markets; decentralized resource adequacy.
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