Rule 21 Interconnection

Electric Rule 21 is a tariff that describes the interconnection, operating and metering requirements for generation facilities to be connected to a utility’s distribution system, over which the California Public Utilities Commission (CPUC) has jurisdiction. The Rule 21 tariff for each of California’s large investor-owned utilities (IOUs) is available on each IOU’s website. Note that the posted Rule 21 may not reflect updates to the tariff that are pending before the CPUC: 

Rule 21 Tariff/Interconnection url
 PG&E  Rule 21 Tariff    Interconnection Website  
 SCE   Rule 21 Tariff  Interconnection Website  
 SDG&E   Rule 21 Tariff    Interconnection Website


Rule 21 Ombudsmen - for dispute-related inquires

Mike Mulvey
Rod Vickers
Kellen Gill

Annoucement:  New Rule 21 Rulemaking  

On June 29, 2017, the Commission issued a draft Order Instituting Rulemaking to Consider Streamlining Interconnection of Distributed Energy Resources and Improvements to Rule 21.  The Commission will vote on whether to adopt the OIR at the July 13th voting meeting. 

The OIR proposes the following schedule for adoption, comments, reply comments, and a prehearing conference:


OIR issued
July 13, 2017
Comments on preliminary scope grouping of issues by tracks, schedule,
 categorization, and need for hearings
August 2,2017
Reply comments on preliminary scopye, grouping of issues by tracks,
schedule, categorization, and need for hearings
August 14, 2017
Pre-Hearing Conference September 2017


Staff Proposal for an Expedited Dispute Resolution Process

Status Update (7/10/17):  Thank you to stakeholders for submitting informal written comments on the "Staff Concept Paper for an Expedited Dispute Resolution Process."  The Commission is reviewing comments and reply comments and is on track to issue a Draft Resolution adopting the Expedited Process by early September.  The finalized staff proposal will be made public at that time.

 On May 30, 2017, CPUC Staff released a straw proposal entitled:  "Staff Concept Paper for an Expedited Interconnection Dispute Resolution Process."  The purpose of this paper is to:

  • Propose an expedited interconnection dispute resolution process as authorized by Assembly Bill 2861 (Ting, 2016),  
  • Solicit feedback from stakeholders on program design elements, and
  • Inform the development of a staff proposal which will serve as the basis for an Administrative Law Judge Resolution to establish the expedited process 

Staff accepted informal written comments and reply comment on the Staff Concept Paper in June 2017.  More information on the process and schedule for final adoption of the Expedited Process can be found in the Staff Concept Paper's introduction section and in the table below:


Activity Estimate Date
Staff Concept Paper Issused May 30, 2017
Stakeholder Comments Due June 23, 2017
Reply Comments Due June 30, 2017
Staff Proposal Finalized August 3, 2017
Draft Resolution Issued September 8, 2017
Comments on Draft Resolution Due September 28, 2017
Commission Vote on Resolution October 12, 2017
Interconnection Dispute Resolution Panel Assembled* March 31, 2018
Expedited Process Launched (accepting applications) March 31, 2018

*The Expedited Process centers on the recommendations of a panel of technical experts, four of whom will be hired by the CPUC using state contracting procedures.  The CPUC's ability to procure the services of the independent experts in a timely manner will impact the timeline to launch.  Based on current staffing constraints within the CPUC's Contracts Office, the estimated timeframe for contracting four panel members is six to nine months.  The timeline below assumes a six-month contracting period.

Rule 21 Links and Resources

  • The Smart Inverter Working Group meets on a regular basis to develop advanced inverter functionality
  • Utility Interconnection Data Reports are submitted to Energy Division quarterly and made available on the CPUC's webpage.
  • D.16-06-052 is a CPUC Decision instituting a 25% Cost Envelope; granting Joint Motions on Cost Certainty and Non-Exporting, Behind-the-Meter Energy Storage; and requiring Rule 21 revisions to incorporate technical requirements for Phase 2 Smart Inverter Communications and Phase 3 Advanced Inverter Functions.


Contact Us

For utility-specific interconnection inquires, please contact the relevant utility using the contact information found on the utility's interconnection website (see links at the top of this page).  For general inquiries concerning Rule 21 and the CPUC's role in overseeing utility interconnection practices, please contact Mary Claire Evans, Regulatory Analyst at


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