Interconnection request and study

New resources interested in interconnecting to the ISO controlled grid are required to complete a study process. To begin the study process, resources must submit an Interconnection Request into a tariff-defined study process.

Interconnection generation process

Transmission-level resource interconnection

In general, if the desired interconnection voltage level is listed below, an Interconnection Request should be filed with the ISO. Review the Interconnection Area Substation Point of Interconnection (POI) List to determine if the desired POI is ISO controlled. Contact for additional assistance.

  • Pacific Gas & Electric service area: transmission lines 60 kV and higher
  • Southern California Edison service area: several 66 kV and 115 kV lines and all transmission lines 220 kV and 500 kV
  • San Diego Gas & Electric service area: transmission lines 69 kV and higher
  • Municipal utility service areas: some lines owned by the municipal utilities but outside of the cities’ boundaries
  • Valley Electric Association service area: transmission lines 138 kV
  • GridLiance West service area: transmission lines 230 kV and 500 kV
  • Ten West Link Delaney to Colorado River (DCRT): 500 kV transmission line
  • DesertLink Harry Allen to Eldorado (DSLK): 500 kV transmission line
  • Other transmission lines: Trans-Elect NTD Path 15, Startrans, Trans Bay Cable, Western Area Power Administration-Path 15, and several lines outside the ISO Balancing Authority which have been turned over to ISO for operational control

Informational presentations and guidelines

The generator interconnection planning process provides a pathway for power plants to interconnect to the ISO controlled grid. We provide information and resources to help you understand and comply with requirements.

Learn about the many facets of interconnection application—from how to apply, the requirements, and what to anticipate during the process.

Generator Interconnection Deliverability Allocation Procedures Customer Guidelines

Save the Date - Resource Interconnection Standards Fair on 9/17/24 | California ISO (

To confirm which interconnection study is appropriate, check with the utility that serves the territory where the project is located.

Submit an interconnection request for study

Determine which available study process is appropriate for your interconnecting facility then submit an interconnection request to begin the study. Interconnection requests are submitted electronically, including the interconnection request document below, through the ISO Resource Interconnection Management System (RIMS) application.

To submit a new interconnection request or update an existing interconnection request, use the Interconnection Request (Appendix 1) Microsoft Word template and the Generating Facility Data (Attachment A to Appendix 1) Microsoft Excel spreadsheet – both documents are required. Sample completed templates for both document types are available for reference.

Interconnection study options

The ISO has four interconnection options for resources interconnecting to the high voltage ISO controlled transmission system:

1. Cluster study process

Designed for most interconnection customers. See Tariff Appendix DD Section 3.

  • Request window is open once per year: April 1 - April 15 or the following business day.
  • All projects in a cluster are assigned a queue position number and have equal standing within the cluster.

2. Independent study process

Designed for interconnection customers for which the Cluster Process will not accommodate the desired Commercial Operation Date (COD) and are electrically independent. See Tariff Appendix DD Section 4.

  • An applicant may apply at any time of the year; however, it is advantageous to submit the applications anytime between November and March.

3. Fast track study process

Designed for interconnection customers developing or adding less than 5 MW and is requesting Energy Only Deliverability. See Tariff Appendix DD Section 5.


* Customer Options meetings are needed if they fail screens. Additional supplemental review meeting based on the outcomes of the customer options meetings (includes a short study process and additional deposit for estimated costs).

  • An applicant may apply at any time of the year

4. ISO as an affected system study

Designed for interconnection customer in Balancing Authority Areas that may affect the reliability of the ISO Controlled Grid. See Tariff Appendix DD Section 14.5.


Affected systems

The ISO will notify the Affected System Operators that are potentially affected by the Interconnection Customer’s Interconnection Request. If required by an Identified Affected System, the Interconnection Customer will sign separate study agreements with the Identified Affected System and pay for necessary studies. See Tariff Appendix DD, section 3.7.

Participating transmission owner financial security instruments

Use our standardized forms to post Interconnection Financial Security with the applicable Participating Transmission Owner.

DCR Transmission (DCRT)
GridLiance West (GLW)
Pacific Gas and Electric Co. (PG&E)
Southern California Edison (SCE)
San Diego Gas and Electric (SDGE)
Valley Electric Association (VEA)

Participating transmission owner per unit costs

Learn the anticipated costs of procuring and installing facilities required to interconnect generation to the applicable Participating Transmission Owner.

Current cost guides

Generator interconnection planning process

Continue on in the generator interconnection planning process.


Related ISO Tariff and Business Practice Manuals

The California ISO operates under the terms and conditions of its FERC-approved tariff. Business practice manuals provide detailed rules, procedures and examples for the administration, operation, planning and accounting requirements of the ISO and the market that are consistent with the ISO tariff.

All new interconnection requests are subject to Tariff Appendix DD. Repower and modification requests are subject to Section 25 and Tariff Appendix DD. New interconnection requests are no longer accepted under Tariff Appendices S, U, W or Y.

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