The ISO provides resources and learning opportunities for the Western Energy Imbalance Market and Extended Day-Ahead Market participants and their transition customers

Resources

Western Energy Imbalance Market (WEIM) Participants

These resources are intended for WEIM entities and participating generators that are directly involved in the Western Energy Imbalance Market.

Business Practice Manuals

Business Practice Manuals contain implementation details through which the California ISO and market participants conduct business in accordance with the Tariff. The Business Practice Manual for Western Energy Imbalance Market contains information about all WEIM entity types.

Tariff

The Western Energy Imbalance Market is governed by the California ISO (ISO) FERC-approved Tariff. Each section or appendix of the tariff is maintained and updated independently according to effective dates of the FERC accepted tariff amendment.

Section 29 of the ISO Tariff addresses the provisions related to the Western Energy Imbalance Market. Appendix B. 17 – 20 contains agreements related to WEIM participation.

Integrate with the ISO full network model

The network model defines system parameters, price node and market scheduling limit mappings and planned network model updates.

Western Energy Imbalance Market Full Network Model Schedule - 202507/22/2025, 11:05 AM
Western Energy Imbalance Market Full Network Model Schedule - 202605/21/2025, 11:29 AM
Modeling Submission Checklist09/10/2024, 4:31 PM
Western Energy Imbalance Market Generator Resource Data Template Version 18.008/02/2024, 2:08 PM
Western Energy Imbalance Market Full Network Model Late Scope Change Request Form03/30/2023, 9:49 AM
Western Energy Imbalance Market Interchange Definition Template12/16/2020, 10:24 AM
Western Energy Imbalance Market Full Network Model Scope Template11/02/2020, 3:43 PM

WEIM Resource Onboarding Procedure

This procedure helps WEIM entities submit the required onboarding documentation for new participating and non-participating resources. The procedure also applies when a non-participating resource would like to become a participating resource.

Energy Imbalance Market Scheduling Coordinator Request for BSCID - Letter Template11/15/2025, 11:49 AM
Western Energy Imbalance Market Procedure for Non-Participating and Participating Resources10/10/2025, 3:06 PM
WEIM - Resource Owner Scheduling Coordinator Selection - Letter Template10/06/2025, 10:54 AM
WEIM - New Scheduling Coordinator Acceptance - Resource - Letter Template10/06/2025, 10:54 AM
WEIM - Transfer - Resources Between BSCIDs - Same Scheduling Coordinator05/20/2025, 11:41 AM
WEIM - Transfer - Resource Relinquishing Scheduling Coordinator - Letter Template05/20/2025, 11:41 AM
Resource Control Agreement Disclosure Form08/02/2024, 2:08 PM
For use with new resource configuration and resource transfers. This will be submitted by the accepting/new SC.

Transmission customers of WEIM entities

Our computer based training modules are for Transmission Customers of WEIM Entities to learn about participation in the WEIM, the real-time market, base schedules, system outages, metering and settlements. For WEIM updates, subscribe to news releases and notices.

Transmission customers should contact their WEIM entity for most questions. For all other questions, contact ISO customer service.

Regulatory Filings

All publicly available California ISO-authored filings and FERC orders are posted on the ISO website.

ISO Department of Market Monitoring

The ISO Department of Market Monitoring (DMM) keeps a close watch on the efficiency and competitiveness of the Western Energy Imbalance Market. Links to tariff provisions discussing DMM’s role and responsibilities and various DMM reports, presentations and tariff filings are available on the ISO website.

Computer Based Training (CBT)

Learning center courses

Western Energy Imbalance Market training

Explore topics pertaining to the real-time energy imbalance market that enables participants to buy and sell energy when needed.

Resources​