PV SYSTEM CODE COMPLIANCE - AEE Solar

PV SYSTEM CODE COMPLIANCEBill BrooksPrincipal, BrooksEngineeringJanuary 18-19, 2016San Diego, CA

SESSION TOPICS NEC Code Basic Principles NEC Code Advanced Topics

Photovoltaic SystemBasics

Current varies with irradiance

Voltage varies with temperature

NEC Article 690 overview

PV Systems and the NEC Article 690 addresses safety standardsfor the installation of PV systems. Many other articles of the NEC mayalso apply to most PV installations.

NEC Sections Applicable to PV Systems Article 110: Requirements forElectrical Installations Chapter 2: Wiring and ProtectionMost of the chapter--especiallyArticle 250: Grounding Chapter 3: Wiring Methods andMaterialsMost of the chapter—especiallyArticle 300: Wiring MethodsArticle 310: Conductors for General Wiring Article 480: Storage Batteries Article 690: Solar PhotovoltaicSystems

NEC Article 690:Solar Photovoltaic Systems I. General (definitions, installation)II. Circuit Requirements (sizing, protection)III. Disconnect Means (switches, breakers)IV. Wiring methods (connectors)V. Grounding (array, equipment)VI. Markings (ratings, polarity, identification)VII. Connection to Other SourcesVIII. Storage batteriesIX. Systems over 600 Volts

Key Code References and Summary of2011 Updates Numerous notable updates to the2011 NEC. Routing and identificationrequirements for conductors. Series Arc Fault detectors requiredabove 80 volts. 690.64 moved to 705.12(D)

Key Code References and Summary of2014 Updates 690.5 GFP must detect grounded conductor faults. 690.7 applies up to 1000V for other thanresidential rooftop systems. Arc-fault protection required for ground-mount. 690.12-Rapid Shutdown required. 690.15-Combiners require disconnects 690.13(B) requires separation of dc and acconductors in a PV system 690.13 through 690.17 completely reorganizedand rewritten—better but not great.

Key Code References and Summary of2014 Updates (cont.) 690.31(C)(2) Cable Tray allowed for all PV Wireprovided it is supported every 12” & secured-4.5’ 690.31(D) Multiconductor TC-ER allowed. 690.35(D) Metallic-jacketed cable and direct burialcable allowed in ungrounded PV systems 705.12(D) Completely overhauled. 705.31 Line-side connections require OCPD within10’ of connection or current limiters 705.100 Single-phase inverters allowed on 3phase systems.

Key Code References and Summary of2017 Updates Reference to new Article 691, Large-Scale PVSupply Stations 690.1 Signs to clarify PV System Disconnectlocation. 690.2 New definition for Functional Grounded PV 690.4 Multiple PV Systems rather than inverters 690.5 Moved to 690.41 690.7 Heavily revised and reduced. 3 methodsallowed for calculating PV voltage. 690.8 Options for calculating current. 690.9 OCPD in either or – of PV array.

Key Code References and Summary of2017 Updates (cont.) 690.10 Section moved to new Article 710. 690.11 Ground-mount PV output circuit optionsnot requiring AFP. 690.12 Rapid Shutdown—Requirements nowinside the array in addition to outside the array. 690.13 Rewritten to clarify PV System Disco 690.15 Equipment disconnects now specificallyallows connectorization of any inverters. Allconductors must be disconnected (dc /-) 690.16 through 19 GONE

Key Code References and Summary of2017 Updates (cont.) 690.31 All PV systems wired same way (USE-2 orPV Wire, one OCPD, disconnect in &-) 690.35 GONE 690.41 Clarifies that we install functionallygrounded PV systems (solid grounding rare) 690.43 Cleaned up and simplified 690.47 Completely revamped. Simply requiresEGC to be connected to local grounding electrode. 690.60 through end is GONE with a fewreferences remaining. Battery section moved tonew Article 706.

690.4(H) Multiple Inverters Where inverters are remotely locatedfrom each other, a permanent plaqueor directory, denoting all electricpower sources on or in the premises,must be installed at each serviceequipment location and allinterconnected electric powerproduction sources [705.10]. Ex: A directory isn’t required whereall inverters and PV dc disconnectingmeans are grouped at the servicedisconnecting means.18

Part II. Circuit Requirements19

690.7 Maximum System Voltage Note: A statistically valid source forlowest-expected ambient temperature isthe Extreme Annual Mean MinimumDesign Dry Bulb Temperature found inthe ASHRAE Handbook —Fundamentals [2011].—available atwww.solarabcs.org/permitting20

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Vmax Module Voc x Table690.7 C.F. x # Modules per String PV Vmax 37 Voc x 1.14 x 14 PV Vmax 591 Voc22

Vmax Rated Voc {1 [(Min.Temp.ºC - 25ºC) Coeff%/ºC]} #Modules Vmax 37Vx{1 [(-7ºC-25ºC)x.32%/ºC]}x14 Vmax 37Vx{1 [(-32ºC) x 0.32%/ºC]} x 14 Vmax 37V x {1 10.24%} x 14 Vmax 37 V x {1.1024} x 14 Vmax 40.79V x 14 Vmax 571 Voc23

Vmax {Voc [(Min. Temp. ºC 25ºC) x Module Coeff V/ºC]} xModules in String Vmax {37V [(-7ºC-25ºC)x0.126V/ºC]}x14Vmax {37V [-32ºC x 0.126V/ºC]} x 14 Vmax {37V 4.0V} x 14Vmax {41V} x 14Vmax 574V24

2014 NEC Revisions:690.7—Maximum Voltage

Article 690.7 Applies up to 1000V for“other installations” “(C) Photovoltaic Source and OutputCircuits. In one and two-familydwellings, PV source circuits and PVoutput circuits that do not includelampholders, fixtures, or receptaclesshall be permitted to have amaximum PV system voltage up to600 volts. Other installations with amaximum PV system voltage over1000 volts shall comply with Article690, Part IX.”

Related Part IX. Systemsover 1000 Volts “690.80 General. Solar PVsystems with a maximum systemvoltage over 1000 volts dc shallcomply with Article 490 andother requirements applicable toinstallations rated over 1000volts.” This basically says 1000V or lessis governed by Article 690.

Implications of new 690.7—it’s a big deal. Changing “600V” to “1000V” meansthat we stay in article 690 instead ofbeing subjected to article 490requirements. Products listed for PV systems up to1000V can be installed on non-oneand two-family dwellings.

690.8(B) OvercurrentProtection PV circuit overcurrent, when required,must be sized to carry not less than125 percent of 690.8(A) calculatedcurrent.29

690.8 Circuit Sizing andProtection (B)(2)(a) Circuit conductors must besized to carry 125% of the maximumcurrent as calculated in 690.8(A)without conductor adjustment andcorrection factors of 310.15.30

690.8 Circuit Sizing andProtection (B)(2)(b) Circuit conductors must besized to carry 100% the maximumcurrent as calculated in 690.8(A)after the application of conductoradjustment and correction of 310.15.31

690.9(A) Circuit OvercurrentProtection For an ungrounded system [690.35],both the plus and minus conductorsmust have overcurrent protection. For grounded systems, only theungrounded conductor requiresovercurrent protection [240.15].32

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Part III. Disconnecting Means34

2014 NEC Revisions:690.15(C)—DC CombinerDisconnects

(C) Direct-CurrentCombiner Disconnects. “The dc output of dc combinersmounted on roofs of dwellings orother buildings shall have a loadbreak disconnecting means located inthe combiner or within 1.8 m (6 ft) ofthe combiner. The disconnectingmeans shall be permitted to beremotely controlled but shall bemanually operable locally whencontrol power is not available.”

690.15(C)—DC Combiner DisconnectsCompliance Options1. string combiner with contactor(mounted within 10 feet of the arrayif rooftop)2. string combiner with motorizeddisconnect (mounted within 10 feetof the array if rooftop)3. String combiner box with nearbyswitch (6’) (likely only used forground mount systems that do notrequire rapid shutdown)

III. Disconnecting Means [2014 NEC]Article 690.15(A) Moved from 690.14(D) to 690.15(A) UtilityInteractive Inverters Mounted in NotReadily Accessible Locations. Utilityinteractive inverters shall be permitted to bemounted on roofs or other exterior areasthat are not readily accessible. Theseinstallations shall comply with (1) through(4):(1) A dc PV disconnecting means shall be mounted withinsight of or in each inverter.(2) An ac disconnecting means shall be mounted withinsight of or in each inverter.(3) The ac output conductors from the inverter and anadditional ac disconnecting means for the inverter shallcomply with 690.13(A).(4) A plaque shall be installed in accordance with 705.10.

690.15 Disconnection ofPhotovoltaic Equipment A disconnecting means isrequired for inverters, batteries,and charge controllers from allungrounded conductors of allsources. If the equipment is energizedfrom more than one source, thedisconnecting means for allsources must be grouped andidentified.39

690.16(B) Fuse Servicing The disconnect must be withinsight of or integral with the fuseholder, be externally operable,and plainly indicating whether inthe open or closed position. Where the disconnecting islocated more than 6 ft from thefuse, a directory showing thelocation of the fuse disconnectmust be installed at the fuselocation.40

(B) Identification and Grouping. “PV source circuits and PV outputcircuits shall not be contained in thesame raceway, cable tray, cable,outlet box, junction box, or similarfitting as conductors, feeders, branchcircuits of other non-PV systems, orinverter output circuits, unless theconductors of the different systemsare separated by a partition.”

690.31(B) changeimplications No longer allowed to run dc and acfrom the inverter in the same gutter.Gutter would require a partition or acraceway would have to continuethrough the gutter so that separationis maintained.

690.31(C)(2) Cable Tray. “PV source circuits and PV outputcircuits using single-conductor cablelisted and labeled as photovoltaic(PV) wire of all sizes, with or withouta cable tray marking/rating, shall bepermitted in cable trays installed inoutdoor locations, provided that thecables are supported at intervals notto exceed 300 mm (12 in.) andsecured at intervals not to exceed 1.4m (4.5 ft).”

690.31(C)(2) Cable TrayApplication 2014 NEC now makes it clear thatproducts specifically designed forcable support can be used forcable support (no size limitationswhen using PV Wire) Support rungs must be no furtherapart than 12” and cables must besecured (cable ties) at intervals4.5’ or less.

690.31(D)Multiconductor Cable. “Multiconductor cable Type TC-ER or TypeUSE-2 shall be permitted in outdoorlocations in PV inverter output circuitswhere used with utility-interactive invertersmounted in locations that are not readilyaccessible. The cable shall be secured atintervals not exceeding 1.8 m (6 ft).Equipment grounding for the utilizationequipment shall be provided by anequipment grounding conductor within thecable.”

690.33 Connectors46

Article 690.33 [2008 NEC]Connectors New language in 690.33(E) (E) Interruption of Circuit.Connectors shall be either (1) or (2): (1) Be rated for interrupting currentwithout hazard to the operator. (2) Be a type that requires the use ofa tool to open and marked “Do NotDisconnect Under Load” or “Not forCurrent Interrupting.”

Article 690.35 UngroundedPhotovoltaic Power Systems Ungrounded systems have not beenprohibited, but the 2005 NEC was thefirst code cycle where therequirements are specifically calledout. Included is an exception in 690.41for consistency.