Transmission planning

Transmission planning at the ISO actively engages stakeholder and public input and uses the best engineering analysis possible to determine short- and long-term infrastructure needs.

Transmission plans

The annual transmission plan serves as the formal and Board-approved roadmap for infrastructure requirements for the ISO balancing authority. ISO and participating transmission owner studies demonstrate how the ISO is planning for infrastructure needs while meeting North American Electric Reliability Corporation and ISO planning standards.

Current plan

See previous transmission plans. 

Plans under development

Standards and processes

The Transmission Planning Standards assure consistent reliability standards across the ISO controlled grid, above those established by NERC and WECC that will maintain or improve transmission system reliability to a level appropriate for the California system and will ensure secure and reliable operation of the ISO controlled grid. View the previous planning standards and processes.

ISO, CEC and CPUC

Memorandum of Understanding

The Memorandum of Understanding (MOU) is an agreement between The California Public Utilities Commission (CPUC), The California Energy Commission (CEC), and the ISO. The MOU tightens the linkages between resource and transmission planning activities, interconnection processes and resource procurement so California is better equipped to meet its reliability needs and clean-energy policy objectives required by Senate Bill 100.

Transmission planning engagement

Request window

During a two-month period in Phase 2 of the Transmission Planning Process, parties may submit potential mitigation solutions, either transmission or non-transmission alternatives, to address reliability constraints identified in the current planning cycle.

  • Request Window Submission Form and Attachment A05/14/2015, 1:24 PM

    Form used in Phase 2 during the two-month Request Window to submit potential mitigation solutions, either transmission or non-transmission alternatives, to address reliability constraints identified in the current planning cycle.

Competitive solicitation process

Project sponsor

To become a project sponsor, submit a proposal, the application form, and workbook for the Transmission Planning Process phase 3 competitive solicitation process. More information about this process is available in the application.

Approved project sponsor

Once selected as an approved project sponsor, a construction plan is needed. Use the construction status report template for the initial construction plan and the subsequent construction plan status reports in accordance with Section 24.6 of the California ISO Tariff.

Submittal requirements - data for power system modeling and analysis

Project sponsors use these documents when submitting proposals for the competitive solicitation process.

North American Electric Reliability Corporation (NERC) - MOD-32-1

Documentation regarding base case development and data submittal requirements for transmission and generation owners in accordance with NERC Reliability Standard MOD-032-1

Submittal requirements - transmission planning process (TPP) BPM

Data templates, resource list, and documentation regarding base case development and data submittal requirements for participating generator owners in accordance with ISO’s Transmission Planning Process Business Practice Manual (BPM).

Accessing transmission data

Transmission planning base case data

The ISO provides access to its regional transmission planning base case data and dynamic data files to members of the Western Electricity Coordinating Council (WECC) and non-WECC members who have an approved WECC Base Case Data Request Package prior to requesting access to this data. Requesting entities must submit a Regional Transmission Non-Disclosure Agreement (NDA). Please review the Submission Instructions before submitting any forms for thorough instructions and links to the necessary forms.

Accessing positive sequence load flow data and dynamic models descriptions

General Electric International, Inc. (GEII) is the only party authorized to distribute GE Positive Sequence Load Flow (PSLF) reference manuals to other parties. A non-PSLF licensed user wanting copies of the load flow data and dynamic models export/import documents needs to contact GEII.

Please direct all questions and access requests for a PSLF license to GEII at pslf-caiso@ge.com.

Planning coordinator services

A Planning Coordinator coordinates and integrates transmission facility and service plans, resource plans, and protection system plans among the Transmission Planner(s), Resource Planner(s), and Distribution Provider(s) within its area of purview. As a Planning Coordinator, the ISO provides the Planning Coordinator functions set forth in the Reliability Standards to NERC registered Transmission Planners, Resource Planners, and Distribution Providers that are connected to the transmission network under ISO operational control.

Transmission access charge (TAC) forecast model

This model is used to project TAC impact of the capital program in each year’s transmission plan.

Title Type Posted
2023-2024 Transmission Access Charge - High Voltage Capital Cost Estimates
Report 09/20/2024, 9:15 AM
2023-2024 Transmission Access Charge - Forecast Model with New Capital
Report 09/20/2024, 9:15 AM
2022-2023 Transmission Access Charge - High Voltage Capital Cost Estimates
Report 10/03/2023, 1:09 PM
2022-2023 Transmission Access Charge - Forecast Model with New Capital
Report 10/02/2023, 3:20 PM
2021-2022 Transmission Access Charge Forecast Model with New Capital
Report 09/23/2022, 2:44 PM
2021-2022 Transmission Access Charge - High Voltage Capital Cost Estimates
Report 09/23/2022, 2:44 PM
2020-2021 Transmission Access Charge -High Voltage Capital Cost Estimates
Report 09/23/2021, 4:35 PM
2020-2021 Transmission Access Charge Forecast Model with New Capital
Report 09/23/2021, 4:35 PM
2019-2020 Transmission Access Charge -High Voltage Capital Cost Estimates
Report 07/13/2020, 2:43 PM
2019-2020 Transmission Access Charge Forecast Model with New Capital
Report 07/13/2020, 2:43 PM
Presentation - 2019-2020 Transmission Access Charge Model
Presentation 07/13/2020, 2:43 PM
2018-2019 Transmission Access Charge Forecast Model with New Capital
06/07/2019, 11:25 AM
2018-2019 Transmission Access Charge - High Voltage Capital Cost Estimates
05/14/2019, 1:14 PM
Presentation - 2018-2019 Transmission Access Charge Forecast Model - May 17, 2019
Presentation 05/14/2019, 1:14 PM
2017-2018 Instructions for Transmission Access Charge Forecast Model
Paper 11/02/2018, 2:02 PM
2017-2018 Transmission Access Charge - High Voltage Capital Cost Estimates
Paper 11/02/2018, 2:02 PM
Presentation - 2017-2018 Transmission Access Charge Forecast Model
Paper 11/02/2018, 2:02 PM
2017-2018 Transmission Access Charge Forecast Model with New Capital
Paper 11/02/2018, 2:02 PM
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Information provided for CPUC integrated resource plan

See information on transmission capability estimate inputs for CPUC integrated resource planning. 

Related ISO Tariff and Business Practice Manual

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