Smart Inverter Working Group

The Smart Inverter Working Group (SIWG) grew out of a collaboration between the CPUC and California Energy Commission (CEC) in early 2013 that identified the development of advanced inverter functionality as an important strategy to mitigate the impact of high penetrations of distributed energy resources (DERs).The SIWG has pursued development of advanced inverter functionality over three phases. Phase 1 considered autonomous functions that all inverter-connected DERs in California will be required to perform.Phase 2 considered the default protocols for communications between IOUs, DERs, and DER aggregators. Phase 3 is currently considering additional advanced inverter functionality that may or may not require communications.

For more information on the SIWG, please contact Jose Aliaga-Caro at



Capability Required by: 

Requirement Detailed in: 

Phase 1 Autonomous Functions 

September 8, 2017

Section Hh of Electric Tariff Rule 21 (Links to each utility’s Rule 21 can be found here).

Phase 2 Communication Protocols

March 22, 2020

Section Hh of Electric Tariff Rule 21 (Links to each utility’s Rule 21 can be found here).

Phase 3 Advanced Functions 

Functions 5/6 - February 22, 2019 
Functions 1,2,3 and 8 - March 22, 2020 
Functions 4 and 7 - TBD 

SIWG recommendations on Phase 3 can be found here.


Recent Meetings

June 18, 2020: D.2006017 Implementation

Decision (D.)2006017 within the CPUC’s Microgrids Rulemaking (R.)1909009, approved on 6/11, orders that the investor-owned utilities (IOUs) work with the SIWG to determine technical implementation details of various proposals. In this meeting, we discussed the implementation of the recent Decision’s Ordering Paragraphs (OP) 1, which relates to the development of single line diagrams for template-based interconnection, and OP 5, which allows energy storage systems that are interconnected under the condition that they charge from solar to temporarily import from the grid ahead of an upcoming Public Safety Power Shutoff (PSPS) event.

June 25, 2020: D.2006017 Implementation (cont.)

July 23, 2020: Harmonization of Rule 21 with IEEE 1547-2018 and 1547.1-2020 (Overview)

August 6, 2020: Development of Rule 21 Cybersecurity Requirements

August 20, 2020:  IEEE 1547.1-2020 Section 1

September 3, 2020:  Development of Rule 21 Cybersecurity

September 17, 2020:  IEEE 1547.1-2020 Section 5

October 1, 2020:  IEEE 1547.1-2020 Section 5 (cont.) and Section 6

October 15, 2020:  IOU Presentation of Proposed Outline of Cybersecurity Requirements Guide  

October 29, 2020:  IEEE 1547-2018 Section 6 Discussion

November 12, 2020: IEEE 1547-2018 Section 6 Discussion (cont.)

November 19, 2020: Utility Cybersecurity Requirement Guide Topic 1: Document Overview

  • 11192020 SIWG Deck
  • The draft Utility Cybersecurity Requirement Guide will be made available for peer review after the completion of all sections.  This process will commence in May of 2021.  If you would like to be a part of the peer review process, please reach out to Danielle Weizman at

December 3, 2020: IEEE 1547-2018 Sections 4 and 6

December 17, 2020: IEEE 1547-2018 Sections 4 and 6 (cont.)

January 7, 2021: IEEE 1547-2018 Clause 4 continuation, Clauses 7, 8, 9, 10 and 11 Discussion

January 14, 2021: IEEE 1547-2018 Clause 4, 10, and 11 Discussion

January 21, 2021: IEEE 1547-2018 Clause 10 Discussion

February 4, 2021: Utility Cybersecurity Requirement Guide Topic 2: Communication and Concepts

Upcoming Meetings

IEEE 1574.1-2020 was published May 21, 2020, and its release triggers significant efforts on the part of the SIWG in the areas of both requirement harmonization and cybersecurity.  The CPUC invites you to participate in a series of SIWG biweekly calls to address these issues.  Additional topics may be proposed and discussed.  Regular calls take place between 1 and 2:30 PM PST on alternating Thursdays.

Please contact Sophie Meyer at for meeting details.

SIWG History

SIWG materials, presentations from the previous workshops and links to the video webcast can be found on the CEC’s Rule 21 Smart Inverter Working Group website.

SIWG Recommendations for Phase 3 Advanced Functions

The SIWG released it updated Phase 3 Recommendations in March 2017.  Previousely, the SIWG hosted webinar meetings to develop these recommendations as well as discuss coordination issues between the SIWG,  related CPUC proceeding and relevant organizations (California Energy Commission, Institute of Electronic and Electrical Engineers (IEEE), Underwriters Laboratory, etc.).

SIWG Recommendations for Phase 2 Communication Protocols

The SIWG released its Phase 2 Recommendations for Utility Communications with Distributed Energy Resources (DER)Systems with Smart Inverters in February 2015. The IOUs submitted Rule 21 tariff revisions incorporating the Phase 2 recommendations on December 20, 2016.  The Commission's Energy Division subsequently approved the revisions.  The implementation of the recommendations is available through each utility's Rule 21, interconnection technical handbook, and an IEEE 2030.5 Common Smart Inverter Profile (CSIP) Implementation guide.

SIWG Recommendations for Phase 1 Autonomous Functions

In D.14-12-035, the Commission adopted seven functions that smart inverters must perform autonomously. The seven Phase 1 functions will be mandatory for all interconnecting DERs on September 8, 2017.   D14-12-035 was informed by the SIWG's Recommendations for Updating the Technical Requirements for Inverters in Distributed Energy Resources document. 

Petition for Modification of Resolutions E-4898 and E-4832

On February 11, 2019, CALSSA submitted the Petition of the California Solar & Storage Association for Modification of Resolution E-4832 and Resolution E-4898 to the CPUC Energy Division.  This Petition addresses the Smart Inverter Phase 2 communications requirments and Functions 1 (Monitor Key DER Data) and 8 (Scheduling Power Values and Modes) of Smart Inverter Phase 3.  More information and links to the Petition and associated resources can be found here.  The Commission addressed CALSSA's Petition for Modification in Resolution E-5000, which was adopted on July 11, 2019.

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