Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems; 3rd Edition National Renewable Energy Laboratory, Sandia National Laboratory, SunSpec Alliance, and the SunShot National Laboratory Multiyear Partnership (SuNLaMP) PV O&M Best Practices Working Group NREL is a national laboratory of the U.S. Department of Energy Technical Report Office of Energy Efficiency & Renewable Energy NREL/TP-7A40-73822 Operated by the Alliance for Sustainable Energy, LLC December 2018 This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. Contract No. DE-AC36-08GO28308 Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems; 3rd Edition National Renewable Energy Laboratory, Sandia National Laboratory, SunSpec Alliance, and the SunShot National Laboratory Multiyear Partnership (SuNLaMP) PV O&M Best Practices Working Group Suggested Citation National Renewable Energy Laboratory, Sandia National Laboratory, SunSpec Alliance, and the SunShot National Laboratory Multiyear Partnership (SuNLaMP) PV O&M Best Practices Working Group. 2018. Best Practices for Operation and Maintenance of Photovoltaic and Energy Storage Systems; 3rd Edition. Golden, CO: National Renewable Energy Laboratory. NREL/TP-7A40-73822. https://www.nrel.gov/docs/fy19osti/73822.pdf. NREL is a national laboratory of the U.S. Department of Energy Technical Report Office of Energy Efficiency & Renewable Energy NREL/TP-7A40-73822 Operated by the Alliance for Sustainable Energy, LLC December 2018 This report is available at no cost from the National Renewable Energy National Renewable Energy Laboratory Laboratory (NREL) at www.nrel.gov/publications. 15013 Denver West Parkway Golden, CO 80401 Contract No. DE-AC36-08GO28308 303-275-3000 • www.nrel.gov NOTICE This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Office and SuNLaMP Agreement 32315.The views expressed herein do not necessarily represent the views of the DOE or the U.S. Government. This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. U.S. Department of Energy (DOE) reports produced after 1991 and a growing number of pre-1991 documents are available free via www.OSTI.gov. Cover Photos by Dennis Schroeder: (clockwise, left to right) NREL 51934, NREL 45897, NREL 42160, NREL 45891, NREL 48097, NREL 46526. NREL prints on paper that contains recycled content. Acknowledgments The National Renewable Energy Laboratory (NREL), Sandia National Laboratories (SNL), SunSpec Alliance, and Roger Hill were supported by the U.S. Department of Energy (DOE) Solar Energy Technologies Office (SETO) under Agreement 32315 in the production of this report. The authors would like to thank the following working group contributors to this report. Working Group Coordinator Dylan Tansy, SunSpec Alliance Support Team Ammar Qusaibaty, SETO Andy Walker, NREL Eric Lockhart, NREL Travis Lowder, NREL Kari Burman, NREL, ret. Geoff Klise, SNL Roger Hill, consultant Tom Tansy, SunSpec Alliance Tim Keating, SunSpec Alliance Olga Lavrova, SNL Anil Pochiraju, SunSpec Alliance Jessie Deot, SunSpec Alliance Bob Fox, SunSpec Alliance Chuck Kurnik, NREL Interviewees Greg Sellers, Clean Power Finance Jean Paul La Marche, Main Street Power Dirk Michaels, K & L Gates Rue Philips, True South David Kenny, Sunrun Leigh Zanone, Meteocontrol Paul Lanning, Lightbox Energy Sarah Disch, Wells Fargo Andrew Truitt, Distributed Resource Ventures Marco Lopez, Alectris Ross Biesemeyer, First Solar Laks Sampath, Alectris Mark Berger, NextGrid Technologies iii This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. 2017 Working Group Roster Eric Alderman, Airphrame Olga Lavrova, SNL Carlos Alves, Nextera Energy Services Richard Lawrence, Institute for Building Technology Rob Andrews, Queen's University and Safety (IBTS) John Balfour, High Performance PV Eric Lockhart, NREL Stephen Barkaski, FLS Energy Mike Loeser, Strata Solar Jimmy Bergeron, SolarCity Jaya Mallineni, Nexamp Inc. Michael Bolen, Electric Power Research Institute Joseph McCabe, Renewable Energy Champion Peter Bostock, VDE Americas Ryan McCauly, Tritium3 Alex Bradley, DuPont Dirk Michels, Ballard Spahr Bill Brooks, Brooks Engineering Reegan Moen, SOLV Paul Brucke, Brucke Engineering Jamie Mordarski, SMA America Jon Budreski, Air Shark Jesse Moses, Swinerton Renewable Energy Kari Burman, NREL Matt Murphy, Borrego Solar Joe Cain, Solar Energy Industries Assoc.(SEIA) Sean Murphy, SolBright Renewable Energy, LLC Nathan Charles, Enphase Energy Eric Nessl, Strata Solar Daisy Chung, Solar Electric Power Assoc. (SEPA) Christina Nichols, DOE Joe Cunningham, Centrosolar Don Nista, Cypress Creek Renewables Jessie Deot, SunSpec Angelo Purpura, SOLV Skip Dise, Clean Power Research Michael Rogerson, Solar Edge Ron Drobeck, System Operations Live View AJ Rossman, Smart Resource (SOLV) Mary Rottman, Rottman Associates Nadav Enbar, Electric Power Research Institute Laks Sampath, Alectris Cary Fukada, OpTerra Energy Services Jadhav Sandeep, Mahindra Susten Cyrille Godenot, Schneider Electric Rudy Saporite, IBTS Danya Golan, Solar Edge Kenneth Sauer, DNVGL Steve Hanawalt, Power Factors LLC Thomas Sauer, Exxergy Chris Henderson, Ameresco Ulrich KW Schwabe, SEGIS-AC awardees Martin Herzfeld, independent consultant Bill Shisler, NRG Roger Hill, consultant Jeff Southard, Juniper Unmanned Inc. Bill Hoffer, Sunergy Engineering Services Jeff Spies, North American Board of Certified Energy Rebekah Hren, Solar Energy International Professionals (NABCEP) Sandeep Jadhav, Mahindra Susten Kristy Straiton, American Society of Testing and Dirk Jordan, NREL Materials (ASTM) Raymond Kaiser, Amzur Technologies Dylan Tansy, SunSpec Joe Kastner, Radian Generation Tom Tansy, SunSpec Tim Keating, SunSpec Abhay Tilwankar, Mahindra Susten Jason Kechijian, SolBright Ernest (Ernie) Tom, Salt River Project George Kelly, Sunset Technology, Inc. Will Troppe, Power Factors LLC Geoff Klise, SNL Andrew Truitt, Dividend Finance Pramod Krishnani, Terraform Power Andy Walker, NREL Bhushan Kunjeer, Enersaas Carter Wall, Franklin Beach Energy Sarah Kurtz, NREL John Williamson, Array Technologies Paul Lanning, Lightbox Energy Gordon Woodcock, Taitem Engineering, PC Leigh Zanone, 8minutenergy iv This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. 2016 Working Group Roster Eric Alderman, Airphrame Richard Lawrence, National Accreditation Board Carlos Alves, Nextera Energy Services for Certified Energy Professionals (NABCEP) Rob Andrews, Heliolytics Inc. Mike Loeser, Strata Solar John Balfour, High Performance PV Jaya Mallineni, Nexamp Inc. Jimmy Bergeron, SolarCity Joseph McCabe, Renewable Energy Champion Michael Bolen, Electric Power Research Ryan McCauly, Tritium3 Institute (EPRI) Scott McWilliams, Sematech Peter Bostock, VDE Americas Dirk Michels, Ballard Spahr Alex Bradley, DuPont Reegan Moen, Swinerton Renewable Energy Bill Brooks, Brooks Engineering Jamie Mordarski, SMA America LLC Paul Brucke, Brucke Engineering Jesse Moses, Swinerton Renewable Energy Jon Budreski, Air Shark Matt Murphy, Borrego Solar Ben Compton, NextPhase Solar Sean Murphy, SolBright Renewable Energy, LLC Joe Cunningham, Centrosolar Eric Nessl, Strata Solar Skip Dise, Clean Power Research Christina Nichols, DOE Ron Drobeck, SOLV Don Nista, Cypress Creek Renewables Nadav Enbar, EPRI Rue Phillips, True South Renewables Cary Fukada, OpTerra Energy Services Angelo Purpura, Swinerton Renewable Energy Jeff Gilbert, Vigilant Energy Management Michael Rogerson, SolarEdge Danya Golan, SolarEdge AJ Rossman, Smart Resource Shannon Grein, Empyrean Electric Mary Rottman, Rottman Associates Steve Hanawalt, Power Factors LLC Laks Sampath, Alectris Chris Henderson, Ameresco Jadhav Sandeep, Mahindra Susten Martin Herzfeld, consultant Rudy Saporite, IBTS Roger Hill, consultant Ulrich Schwabe, SEGIS-AC awardees Bill Hoffer, Sunergy Engineering Services PLLC Bill Shisler, NRG Rebekah Hren, Solar Energy International Jeff Spies, NABCEP Joe Kastner, Radian Generation Kristy Straiton, ASTM Jason Kechijian, SolBright Abhay Tilwankar, Mahindra Susten George Kelly, Sunset Technology, Inc. Ernest Tom, Salt River Project Ken Kostok, Alectris Will Troppe, Power Factors LLC Pramod Krishnani, Terraform Power Andrew Truitt, Dividend Finance Bhushan Kunjeer, SunEdison Carter Wall, Franklin Beach Energy Sarah Kurtz, NREL David Walter, Hartford Steam Boiler Paul Lanning, Lightbox Energy Gordon Woodcock, Taitem Engineering, PC Olga Lavrova, SNL Leigh Zanone, Meteocontrol v This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications. List of Acronyms AC alternating current AMI advanced metering infrastructure AMR automated meter reading ANSI American National Standards Institute ASNT American Society of Non-destructive Testing ASTM American Society for Testing and Materials BLAST Battery Lifetime Analysis and Simulation Tool CAD computer-aided design CT current transformer DAS data acquisition system DC direct current DOD depth of discharge DOE U.S. Department of Energy EAM enterprise asset management