The California Solar Initiative's RD&D Program has now concluded after operating since 2008 through 2016. All solicitations and research projects are now complete.



 Program overview + Research briefs       

 [25 MB ]
 Program overview  [13 MB ]

 Research briefs  (high resolution)                     

 [44 MB ]

For more information on the research projects and resulting reports please review the section below. All completed final reports are also available separately for review and download. 

FINAL REPORTS for completed projects along with individual research briefs can be found here.


CSI RD&D Program - Program Evaluation 



 Report Summary       

 [277 KB ]
 Final Report  [3 MB ]


 [4 MB ]


Funded Projects

This is a database of projects funded by the CSI RD&D. The project summaries are listed alphabetically below. You may also choose a subset of projects by clicking a keyword, or using the search function.

Screening Distribution Feeders: Alternatives to the 15% Rule

Current Highlights:
  • FINAL Report: Alternatives to the 15% Rule  PDF (2 MB)
  • FINAL Report for Tasks 7 & 8. July 2015.  PDF (2 MB)

Project Information

Solicitation: Solicitation 3
Target Area: Grid Integration
Awardee: Electric Power Research Institute (EPRI)

NREL, Sandia National Lab, and Clean Power Research

CSI Funding: $1,978,239
Match Funding: $1,978,239
Start Date: July 2012
End Date: July 2015
Status: Complete

Contact Information

Principal Investigator Name: Jeff Smith
Principal Investigator Email: jsmith @ epri.com
Principal Investigator Phone: 865-218-8082
Grant Manager Name: William Marin
Grant Manager Email: william.marin @ itron.com
Grant Manager Phone: 509-891-3193

Project Summary

The Electric Power Research Institute (EPRI), in partnership with the National Renewable Energy Laboratory (NREL) and Sandia National Laboratories, is developing an interconnection screening methodology that takes into account individual distribution feeder characteristics. Distribution modeling and simulation techniques will be used to determine the level of photovoltaics (PV) that can be accommodated on individual feeders without impacting distribution system operations. This measure of "hosting capacity" is expected to become more critical as PV deployment increases.

Major California utilities including Pacific Gas & Electric, Southern California Edison, San Diego Gas & Electric and the Sacramento Municipal Utility District are part of the project research team. These utilities will help to detail which tools and penetration screens are most commonly used and which procedures have been most effective for evaluating PV interconnection requests in California. The utilities will also help review distribution feeder classification methods currently used in California to identify and map areas with additional capacity for hosting PV.

Some of the factors known to be important to feeder hosting capacity, and included in the screening methodology, are steady state voltage regulation limits, tap changer cycling issues, reverse power flow issues, unintentional islanding risks, fault current contribution issues, ground-fault relaying desensitization issues, neutral grounding compatibility, ground fault overvoltage issues, and harmonics. These factors will then be used to develop a higher-level screening methodology that can be applied to other distribution systems, without necessitating the need for detailed analysis.

Deliverables and Documents


  • FINAL Report: Alternatives to the 15% Rule. Smith, J., et al. EPRI. December 2015.  PDF (2 MB)
  • FINAL Report for Tasks 7 & 8: Alternatives to the 15% Rule: Modified Screens and Validation. 3002005791. Smith, J., Project Manager. July 2015.  PDF (2 MB)
  • Task 5 & 6 Update:Modeling and Hosting Capacity Analysis of 16 Feeders. 3002005812. Smith, J., Project Manager. Technical Update. April 2015.  PDF  (10 MB)

  • EPRI. Final Technical Report: Clustering Methods and Feeder Selection for PV System Impact Analysis. Palo Alto, CA. March 2014. 3002002562. PDF (1 MB)

  • NREL/EPRI: Current Utility Screening Practices, Technical Tools, Impact Studies, and Mitigation Strategies for Interconnecting PV on the Electric Distribution Systems Final Report. May 2013.  PDF (261 KB)


  • Final project webinar slide deck [PDF]
  • Webinar recording
  • Task 6 Update Presentation: PV Hosting Capacity Analysis of PG&E Feeders. Oct 7, 2014. PDF (3 MB)

  • Task 6 Update Presentation: PV Hosting Capacity Analysis of SDG&E Feeders. Oct 21, 2014. PDF (3.5 MB)

  • SolarForum 2013 Presentation: "Alternative Screening Methods: PV Hosting Capacity in Distribution Systems." Smith, J. Electric Power Research Institute. PDF (1.48 MB)
  • Initial Project Presentation. Aug 9, 2012. PDF



The EPRI team has collected feeder characteristic data for three California utilities. These data are summarized and described in the following documents:

  • Utility 1: PDF (363 KB)
  • Utility 2: PDF (300 KB)
  • Utility 3: PDF (553 KB)

The EPRI team has also collected high-resolution time-series solar irradiance data from 20 monitoring systems installed across selected feeders. The monitoring units include an ac power meter to measure PV system output (real and reactive power, voltages, and currents) and a pyranometer to measure plane-of-array solar irradiance. Data were recorded at 1-second intervals. These data are summarized and described in the following documents:

  • Summary of data collection results. 07-24-2015: PDF (5.5 MB)
  • PV Data Information Jan-Jun 2014 and 2015: Excel (6 KB)
  • PV Data Information Jul-Dec 2015

To obtain a CSV file with the raw data described in the above PDFs, please contact the grant manager William Marin (William.Marin @ Itron.com).

Project Activities

July 2012 Project started
July 2015 Project completion

Project Links

Tags: Interconnection