Reference · Changes to PV modules and array designs may exceed voltage ratings for modules or...

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The requirements for PV system installations and equipment are governed by national codes and standards that are adopted into local building codes. Approvals for PV installations are granted by local jurisdictions through the permitting, plan review and inspection process, and helps ensure the safety of PV systems.

Reference: Photovoltaic Systems, Chap. 13

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Reference: Photovoltaic Systems, p. 350-351

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The authority having jurisdiction (AHJ) is responsible for enforcing building codes through the permitting, plan review and inspection process. Plans examiners and inspectors are typically agents of the AHJ. Electric utilities approve the interconnection of PV systems to the grid.


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The Authority Having Jurisdiction uses the listing and labeling of equipment as a foundation for plans review, field inspection and approval of electrical installations.

A Nationally Recognized Test Laboratory (NRTL) is an OSHA-recognized accredited safety testing and certification organization that lists, labels or accepts, equipment or materials that meet the applicable standards. These independent, third-party approvals provide assurances to AHJs, contractors and consumers that electrical equipment is safe and appropriate for its intended application.

Commonly known NRTLs involved in evaluating PV systems equipment include Underwriters Laboratories (UL), Canadian Standards Association (CSA), IntertekTesting Services NA, Inc. (ITSNA, ETL SEMKO), TUV Rheinland of North America, Inc. (TUV), MET Laboratories, Inc. (MET) and Wyle Laboratories, Inc. (WL).

References:Photovoltaic Systems, p. 350-355NEC 110.2, 90.7

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Instructions provided by equipment manufacturers for listed and labeled products must be followed.

Reference: NEC 110.3

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Insulation resistance testing is commonly used to verify integrity of wiring systems.

References:NEC 110.7, 110.12, 110.14ANSI/NECA 1-2006, Standard Practice for Good Workmanship in Electrical Contracting

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PV installations must be conducted in accordance with local and state contracting laws and regulations. In most cases, these laws require a licensed electrical contractor to pull permits and perform electrical systems work, including PV systems. Some states have special solar licenses that are usually limited in scope, and require a qualified electrical contractor to make interconnections. Licenses are granted by state or local governments and a mandatory requirement to practice a trade in a jurisdiction. A new change for the 2011 NEC requires PV systems to be installed by a qualified person as defined in Article 100.

References: NEC Article 100, 690.4(E)Photovoltaic Systems, p. 355-356http://www.jimdunlopsolar.com/resources/publications/

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While a few jurisdictions have adopted special permitting processes for PV installations, many use standard electrical and building permit applications. Building permits may also be required due to the structural loads associated with mounting PV array to building rooftops and other structures. Permit fees are usually based on the size or cost of the PV system. Code compliance may also require certification from professional engineers for structural aspects of the PV array installation, and the specific building roof load bearing capabilities. Local and state fire safety codes may place additional restrictions on PV installations, such as the size, locations of arrays on building rooftops, and allowing clear pathways for firefighter access, and for venting of roofs.

References:Photovoltaic Systems, p. 357-361Expedited Permit Process for PV Systems - A Standardized Process for the Review of Small-Scale PV Systems, Solar America Board for Codes and Standards: www.solarabcs.org

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Reference: Expedited Permit Process for PV Systems: A Standardized Process for the Review of Small-Scale PV Systems, prepared by Bill Brooks and Solar America Board for Codes and Standards: www.solarabcs.org

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Permit applications also usually require a description of the project and scope of work, the property owner name and address, and the contractor name, address and license information. In most jurisdictions, a notice of commencement and certificates of bonding and insurance are usually required for construction contracts.


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References:Photovoltaic Systems, p. 357-361Expedited Permit Process for PV Systems: A Standardized Process for the Review of Small-Scale PV Systems, prepared by Bill Brooks and Solar America Board for Codes and Standards: www.solarabcs.org

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The field inspection process verifies compliance of PV installations in accordance with approved plans, as-built modifications and code requirements.

References:Photovoltaic Systems, p. 361-367Field Inspection Guidelines for PV Systems, 2010 Edition; prepared by Brooks Engineering for Interstate Renewable Energy Council:www.irecusa.org

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Reference: Field Inspection Guidelines for PV Systems, 2010 Edition; prepared by Brooks Engineering for Interstate Renewable Energy Council:www.irecusa.org

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Some sources for PV system inspection checklists include:

http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/Codes-Stds.htmlhttp://www.nmsu.edu/~tdi/pdf-resources/INSPECTOR_CHECKLIST_6-23-06.pdfhttp://irecusa.org/wp-content/uploads/2010/07/PV-Field-Inspection-Guide-June-2010-F-1.pdfhttp://www.jimdunlopsolar.com/vendorimages/jdsolar/PVInspectionChecklist.pdf


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A thorough understanding of the National Electrical Code is critical for qualified PV installers, especially the first four chapters dealing with all electrical installations.

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Changes to PV modules and array designs may exceed voltage ratings for modules or inverters, or result in too low array voltage during higher temperatures. Model numbers are verified by PV module labels, and the configurations can usually be verified by inspecting array wiring and combiner boxes.

Reference: NEC Articles 338, 334

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Reference: NEC 690.33, 110.12

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Exposed array conductors must be secured and supported at least every 4-1/2 feet, and within 12 inches of any junction box, equipment or enclosure. The radius of wire bends must not be less than five times the diameter of the wire or cable. Proper wire management reflects on the skills and competencies of the contractor, and the overall quality of the installation.

Reference: NEC Articles 338, 334, 690.33

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Several methods are permitted to connect PV module equipment grounding conductors to their support structures. Traditional methods use self-tapping screws and cup washers, or lay-in lugs attached to the module frames. Other methods include using bonding washers or clips between module frames and supports. Equipment grounding conductors smaller than 6 AWG must be protected from physical damage, and copper grounding conductors should never be allowed to touch aluminum module frames or supports.

Refer to PV module and mounting system manufacturer installation instructions for specific grounding requirements.

References:Photovoltaic Systems, Chap. 11NEC 690 Part V

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See module and mounting system manufacturer instructions for required locations and installation procedures.


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Working space is a designated area around electrical equipment that permits safe access to workers who examine, adjust, service or maintenance the equipment while it is energized. The minimum required depth, width and height of the working space depends on the voltages and points of access for the equipment. Testing or measuring any PV system components with a handheld meter while the equipment or circuits are energized requires minimum working space. Many PV arrays will operate up 600 volts DC, and if the array combiner boxes are likely to be opened, examined or tested while energized, at least 3 ft depth of working space is required in front of the enclosure. The width of the working space in front of equipment that may be serviced in an energized state must be at least 30 in. or the width of the equipment, whichever is greater. The doors on equipment or hinged panels must also allow at least a 90 degree opening. The working space around electrical equipment must be clear from the floor to a height of 6-1/2 feet or the height of the equipment, whichever is greater, and other electrical equipment above or below may extend into the working space no more than 6 inches.

References: Photovoltaic Systems, p. 362-363NEC 110.262008 NEC Handbook, Exhibits 110.9-110.23

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References:NEC Chapters 1, 2 & 3, Article 690 Part IVPhotovoltaic Systems, Chap. 11

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References:NEC Chapters 1, 2 & 3, Article 690 Part VII, 705 Photovoltaic Systems, Chap. 11

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Numerous labeling requirements apply to PV installations in the 2011 NEC. Some of the required labels and markings are provided on equipment at the time of manufacture, while others are required to be installed in the field by the system installer and require certain system-specific information.

Code-approved markings include identification of the manufacturer, size, type, specifications and ratings for conductors, raceways, overcurrent devices, switchgear and all other electrical components. Normally these markings are placed on the product at the time of manufacture, including the product approval and listing from the approval agency (NRTL), such as UL. Code officials will verify these marking during final inspections.

References:Photovoltaic Systems, p. 363-367NEC 100, 110.2, 110.3, 110.2129 CFR 1926 Subpart GANSI Z35.1-1968, Specifications for Accident Prevention SignsANSI Z535.4-1998, Product Safety Signs and Labels

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Fire codes address the safety of firefighters, and buildings and their occupants. In 2007, the California Office of the State Fire Marshal first adopted guidelines for PV installations relative to firefighter safety. An adaptation of the California guidelines was approved for the 2012 International Fire Code (IFC) and the Uniform Fire Code, NFPA 1.

References:Solar Photovoltaic Installation Guideline, California Dept. of Forestry and Fire Protection, Office of the State Fire Marshal: http://osfm.fire.ca.gov/pdf/reports/solarphotovoltaicguideline.pdfSolar America Board for Codes and Standards: www.solarabcs.org

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Note that there are some minor inconsistencies between fire safety labels recommended in the California firefighter guidelines, and with ANSI label standards. The National Electrical Code also requires marking and labeling for all PV system disconnecting means.

References:Solar Photovoltaic Installation Guideline, California Dept. of Forestry and Fire Protection, Office of the State Fire Marshal: http://osfm.fire.ca.gov/pdf/reports/solarphotovoltaicguideline.pdf

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Fire safety codes require labeling for all DC equipment and wiring systems. These requirements are consistent with new labeling requirements adopted in the 2011 NEC.

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Conductors from different PV systems using the same raceways or junction boxes must also be identified, and grouped by securing together at least every 6 ft if the raceways or junction boxes can be opened.

Reference: NEC 690.4(B)

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Reference: NEC 690.4(D)

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Reference: NEC 690.4(H), 690.15(D), 705.10

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Reference: NEC 690.5(C)

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Reference: NEC 690.7(E)

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Reference: NEC 690.10(C), 690.56(A)

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Reference: NEC 690.14(C), 690.53

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This requirement applies to most DC disconnects.


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Reference: NEC 690.31(E)

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Reference: NEC 690.51, 690.52

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Reference: NEC 690.56(B), 705.10

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All inverters and AC modules that are specifically intended to be used in utility-interactive PV systems must be listed and identified for the purpose. This information must be marked on the product label. Battery-based inverters intended only for stand-alone off-grid applications do not have these special identification markings, and may not be used for grid-connected applications. However, all inverters used in PV systems must be listed to the UL 1741 standard, whether they are used for stand-alone or interactive systems.

References: NEC 690.60, 705.4

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Reference: ANSI Z35.1-1968, Specifications for Accident Prevention Signs

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References:29 CFR 1926 Subpart GANSI Z35.1-1968, Specifications for Accident Prevention SignsANSI Z535.4-1998, Product Safety Signs and Labels

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Reference: Articles on PV system electrical integration and inspection by John Wiles:

http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/Codes-Stds.html

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The UL White Book is a useful resource for electrical building officials, and covers the following categories of PV system and other distributed power equipment:

Distributed Generation Power Systems Equipment (QHWJ) AC Modules (QHYZ)Building-integrated Photovoltaic Modules and Panels (QHZK)Building-integrated Photovoltaic Mounting Systems (QHZQ)Photovoltaic Charge Controllers (QIBP)Photovoltaic Modules and Panels (QIGU)Static Inverters and Converters for Use in Independent Power Systems (QIKH)Photovoltaic Wire (ZKLA)

Reference: www.ul.com

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References:Solar America Board for Codes and Standards: http://www.solarabcs.org/PV Codes and Standards Resource Site: http://www.nmsu.edu/~tdi/Photovoltaics/Codes-Stds/Codes-Stds.html

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