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CAISO interconnection

California ISO coordinates interconnection to the ISO-controlled transmission grid, with the appropriate study path determined by the project and its requested service.

Guide updated October 9, 2026.

Choose the right process​

For new cluster requests, start with Resource Interconnection Standards (RIS), Tariff Appendix KK. CAISO's current request page identifies the cluster study process and other study options. Older projects may remain subject to earlier procedures, so record the governing process and cluster before reusing an application package. Interconnection request and study

New requests are submitted through the Grid Resource Interconnection Portal (GRIP). Establish access early, identify the project company's contacts, and check the published window and portal instructions. The GRIP library contains the current user guide and tutorial material. GRIP documentation

Prepare the application inputs​

Use the current portal fields and generating-facility data template as the filing checklist. Assemble a project record that connects each answer to its supporting document:

  • Applicant identity, project name, primary contacts, and authority to act for the project company.
  • Technology and configuration, including any co-located generation or energy storage.
  • Facility nameplate capacity, requested export, storage charging limits, and requested deliverability treatment.
  • Proposed point of interconnection, transmission owner, voltage, and location.
  • Requested dates, site information, and the supporting exhibits required by the selected process.

CAISO publishes sample application fields and Generating Facility Data — Attachment A to Appendix 1 on its request page. Download the current version before preparing a submission. A previous project's completed form is useful as a reference, but its fields and values should not become a new project's defaults. Application resources

Assemble drawings and models​

Build the technical package around one consistent equipment schedule. For preparation, keep the one-line diagram, transformer data, collector-system representation, plant controls, reactive capability information, and model files together. Confirm the software versions and model deliverables against the current CAISO instructions and the participating transmission owner's requirements.

A useful internal model register records the supplier, file revision, equipment represented, operating mode, units, and outstanding assumptions. For storage and hybrid projects, document charging and discharging separately. Identify where plant-level controls limit export and how auxiliary consumption and electrical losses affect power at the point of interconnection.

Treat model creation and model acceptance as separate milestones. Preserve test results and reviewer responses with the submitted files so that later revisions can be compared against the same project configuration. CAISO's generator interconnection resources are the starting point for the applicable technical material.

Track site evidence and financial milestones​

Maintain an evidence register for the plant footprint, interconnection facilities, and gen-tie route. Link the maps to the legal descriptions and relevant site documents. Record any gaps or exceptions explicitly instead of filling them with assumptions.

Use the governing tariff and current cycle instructions to determine site-control requirements, deposits, security, and readiness evidence. Record the amount, recipient, due date, payment reference, and acknowledgement separately for each obligation. The RIS provisions and financial-security resources are linked from CAISO's request and study page.

Review the package before submission​

The following are useful preparation checks, rather than a complete CAISO validation test:

  1. Reconcile nameplate, inverter totals, requested export, and the capacity shown on every drawing.
  2. Check that the POI, voltage, project name, and legal entity agree across the portal and attachments.
  3. Distinguish confirmed equipment data from study assumptions and unresolved supplier inputs.
  4. Match the geographic layout to the site evidence and proposed electrical route.
  5. Retain the exact submitted package, portal confirmation, and subsequent deficiency responses.

Official sources and scope​

Start with CAISO generator interconnection, the RIS request and study resources, and the GRIP library.

This guide supports preparation and navigation. The effective tariff, current cycle instructions, and project-specific transmission-owner requirements control. A completed checklist does not establish application acceptance or compliance.