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 Jeffrey Kwan 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

Later of (a) March 1, 2018 or (b)
9 months after the release of the SunSpec Alliance communication protocol certification test standard or the release of another industry recognized communication protocol certification test standard

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

Phase 3 Advanced Functions 


Exact requirements have not yet been determined. SIWG recommendations on Phase 3 can be found here.


CPUC Staff Proposal on Power Priority Setting of Smart Inverters

On Thursday, July 27, Energy Division issued a Staff Proposal on Power Setting of Smart Inverters on how the investor-owned utilities (IOUs) can modify the Rule 21 tariffs to transition all grid-connected inverters from reactive power priority to real power priority.  Below are the written comments received by Energy Division.  At this time, Commission Staff does not see the need for reply comments but will consider allowing reply comments if parties request the opportunity to submit them.


Upcoming Meetings

The CPUC and CEC invite you to participate in a series of SIWG weekly calls to develop and finalize Phase 3 requirements for smart inverters.  This series of meetings is a continuation of the meetings which took place over Q1 2017 to develop recommendations on the synchronization of the SIWG Phase 3 Functions with the IEEE 1547 standard and other advanced inverter efforts.  The objective of these upcoming calls through Q3 2017 is to assist the California investor-owned utilities (IOUs) to develop tariff revisions of which they are required to file through Tier 3 advice letters in August 2017.  These tariff revisions will incorporate the recommendations on the Phase 3 Functions previously developed.  Additional topics may be proposed and discussed after completion of the previous issues.

The WebEx call-in information is:

Join WebEx meeting 
Meeting number (access code): 921 191 369      
Meeting password:        1nverter!         

Join by phone  
1-866-469-3239 Call-in toll-free number (US/Canada)  
1-650-429-3300 Call-in toll number (US/Canada)  
Global call-in numbers  |  Toll-free calling restrictions   
Can't join the meeting? Contact support. 

Past Workshops

Thursday, November 17, 2016 - SIWG Workshop on Adoption of Phase 2 and 3 Recommendations

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. 

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