Wholesale Distribution Independent Study and Cluster Study Interconnection Processes

Interconnecting Your Generating Facility with PG&E's Electric Grid

If you plan to develop a solar farm or non-solar generating facility that will produce more than 5 MW of electricity, and you are interested in selling the power you generate on the California Independent System Operator (CAISO) market via PG&E's distribution system, this page is for you.

All generators who wish to connect their self-generation systems to the PG&E electric grid must have an interconnection agreement with PG&E. The Independent Study Process (ISP) and Cluster Study Process (CSP) allow you to apply to interconnect your generating facility to a PG&E substation 12 kV or 21 kV bus through a dedicated circuit—called a "gen-tie"—that you construct. The power you generate typically is redistributed through feeders at the substation and then to other customers through the transmission system.

The Interconnection Process

  • For an overview of the steps required to install and interconnect a solar farm or non-solar generating facility, view the Process Flow slides for Wholesale Distribution Independent Study or Cluster Study  Interconnection.

Differences Between the ISP and CSP

Here's how the ISP and CSP processes differ:

An ISP evaluates an interconnection request for a generating facility independently of other projects. An ISP involves a System Impact Study and a Facilities Impact Study, each of which must be completed within 60 business days. To become eligible for an ISP, you must pass an Electrical Independence Test (EIT) after you apply. This two-part test involves PG&E's and CAISO's evaluation of the interconnection studies of earlier-queued generating facilities to which your facility is electrically related. To find out your potential for passing this test, check the public queue for active projects connecting to the substations at your point of interconnection. The ISP may take six to 12 months. You may apply for an ISP at any time. But if your project fails either part of the EIT, you will be required to wait: Until the next Cluster window (see below) to apply under the Cluster Study Process, or 12 months from the date you were informed of the failure of the EIT to reapply under the ISP for a similar point of interconnection

A CSP evaluates a group of interconnection requests collectively. You may apply for a CSP only during the application window (for more details, please see Section {4.1 of Attachment I: Generation Interconnection Procedures (GIP)} of the Wholesale Distribution Tariff.. Engineering analyses for CSP requests are conducted in two phases. Phase I and Phase II studies identify distribution and reliability network issues or upgrades required to mitigate thermal overloads and voltage violations and address short-circuit, stability, and other reliability issues.

Before you get started, please make sure to contact your local city or county building or planning department to learn about the requirements for your project.

Find your local building department >>

Your Project Site

If your project is in the planning stages, you'll want to check out our Photovoltaic Renewable Auction Mechanism map. It shows important information about PG&E circuit names, the voltage of the electric facility nearest to your project site, loading and more. This information can help you choose an appropriate project site. View the map >>

Understanding Costs

The costs of interconnecting your generating system to the PG&E electric grid will depend on several factors, including the system size, substation and circuit capability and voltage considerations. The electric system nearest your site may not have the capacity to receive the amount of electricity you propose to generate. As a result, you may be required to pay for upgrades to the interconnection facilities, distribution system and network to accommodate your request. Once you and PG&E agree on the scope of your project, PG&E will conduct a study to identify the costs of and schedule for any required upgrades and will communicate this information to you.


Find out more about timelines in PG&E's Independent Study and Cluster Study  Process Flows.

View more specific information about timelines in the Wholesale Distribution Tariff >> (PDF, 1.5 MB)

PG&E is Here to Help

After we receive your completed application package and applicable fees, you will be invited to meet with PG&E to discuss the scope of your project. During your scoping meeting, you and representatives from PG&E's Generation Interconnection Services will:

  • Discuss the PG&E engineering team's initial assessment of the impact of and minimum requirements for establishing an electrical connection between your installation and our distribution system
  • Set expectations for how long it will take PG&E to study and fully assess the impact and requirements described above
  • Give you an overview of the study process and key milestones

PG&E is here to help you navigate the interconnection process and its rules, from submitting your application to obtaining your Permission to Operate. Our Generation Interconnection Services team is here to help you ensure a successful project and a safe, reliable interconnection to the grid. For assistance, please email wholesalegen@pge.com.

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