Project Modul

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0

Expedited Permit Process

for PV Systems

with Detailed Explanationto Help Guide Thru the Process

Preparedfor:

NewMexicoStateUniversity

SolarAmericaBoardforCodesandStandards

(availableatwww.SolarABCS.org)

Preparedby:

BrooksEngineering

873KellsCircle

Vacaville,CA95688

www.brooksolar.com

Version4

May2009


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1

Dedication:

Thisdocumentisdedicatedtotwokeyindividualsthatrepresenttheverybestofthosewho

haveworkedonthecodesandstandardsprocessesastheyrelatetoPVsystems.Thesetwo

amazingpeople,TimOwens,ofSantaClaraBuildingDepartment,andChuckWhitaker,ofBEW

Engineering,passed

away

in

the

months

prior

to

the

release

of

this

standardized

permitting

process.

TimOwens:

TimOwenspassedawayinDecemberof2008attheageof??inthemidstofadistinguished

careerintheelectricaltradesandcodeenforcement.WhileworkingasChiefElectrical

InspectorfortheCityofSanDiegoin1999,Timwasthefirstjurisdictionalofficertoput

togetherasimplifiedpermittingprocessforPVsystems.Hisdesiretoseesuchaprocess

becomecommonplaceiswhathasdriventhisauthortoworkonimprovingpermittingand

approvalprocessesforPVsystemsforthepastdecade.Thesolarcommunity,lostatruefriend

andpartnerwhowasdedicatedtothesuccessofsolarphotovoltaicsystemsinCaliforniaand

therestoftheU.S.

ChuckWhitaker:

ChuckWhitakerpassedawayinearlyMayof2009attheageof50inthemidstofa

distinguishedcareersupportingthedevelopmentandimplementationofmostofthecodesand

standardsthegovernandsupportPVsystemsbothnationallyandinternationally.Hispassing

coincidedwiththeinitialreleaseofthisstandardizedpermittingprocess.Theauthorhadthe

privilegeofknowingChuckfortwodecadesandworkingcloselywithhimforover8yearsashis

employeeand

colleague.

It

is

difficult

to

overstate

Chucks

contribution

to

the

PV

industry

since

hisinfluenceisfoundinnearlyeverycodeandstandardthathasbeendevelopedforPV

equipmentandsystemsoverthepast25years.Itisonlyfittingthatthisdocument,which

includeshisinfluence,bededicatedtohismemory.AhugeholeisleftinthePVindustrywith

Chuckspassing,anditisthehopeofmanyofusinthecodesandstandardsarenatobeableto

carryonhistirelessworkwithasemblanceoftheskill,whit,andhumorthatwasthehallmark

ofthisamazingindividual.


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INTRODUCTION:............................................................................................................................. 3

ExpeditedPermitProcessforSmallScalePVSystems................................................................. 4

ExpeditedPermitGuidelinesforSmallScalePVSystems............................................................ 8

Section1. RequiredInformationforPermit:........................................................................... 8

Section2.

Step

1:

Structural

Review

of

PV

Array

Mounting

System

.......................................

8

Section3. Step2:ElectricalReviewofPVSystem(CalculationsforElectricalDiagram)......10

Section4. InverterInformation............................................................................................. 11

Section5. ModuleInformation.............................................................................................. 12

Section6. Arrayinformation................................................................................................. 13

a) NUMBEROFMODULESINSERIES................................................................................. 13

b) NUMBEROFPARALLELCIRCUITS.................................................................................. 13

c) LOWESTEXPECTEDAMBIENTTEMP............................................................................. 13

d) HIGHESTCONTINUOUSTEMP(ambient)...................................................................... 13

Section7. SIGNS..................................................................................................................... 14

a) PVPOWERSOURCE....................................................................................................... 14

b) WARNINGSIGNREQUIREDBYNEC690.17.................................................................. 15

c) PointofConnectionSign[NEC690.54]......................................................................... 15

Section8. WiringandOvercurrentProtection...................................................................... 16

a) DCWiringSystems:....................................................................................................... 16

b) ACWiringSystems........................................................................................................ 18

Section9. ACPointofConnection......................................................................................... 18

Section10. Grounding......................................................................................................... 19

a) SystemGrounding......................................................................................................... 19

b) EquipmentGrounding................................................................................................... 19

c) SizingofGroundingConductors................................................................................... 20

APPENDIX.....................................................................................................................................

21

APPENDIXA:EXAMPLESUBMITTAL............................................................................................ 22

APPENDIXB:STRUCTURAL.......................................................................................................... 26

STRUCTUREWORKSHEETWKS1................................................................................................... 26

B.2 SPANTABLES..................................................................................................................... 27

SpanTableR802.5.1(1),........................................................................................................ 27

SpanTableR802.5.1(2),........................................................................................................ 28

APPENDIXC:SPECIALELECTRICALTOPICS.................................................................................. 29

ModuleFrameGrounding:........................................................................................................... 29

ACConnectiontoBuildingElectricalSystems.............................................................................. 30

AC

Connection

to

Load

Side

of

Main

Service

Panel

......................................................................

30

ACConnectiontoSubpanel:......................................................................................................... 31

ACSupplySideConnection:.......................................................................................................... 32

SourceCircuitOvercurrentProtection:........................................................................................ 33

DisconnectingMeans:................................................................................................................... 34

Provisionsforthephotovoltaicpowersourcedisconnectingmeans:.........................................35

APPENDIXD:COSTSOFPERMITS................................................................................................ 36

APPENDIXE:TEMPERATURETABLES........................................................................................... 37


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INTRODUCTION:

Theonepageexpeditedpermitprocess,andtheaccompanyingdocumentexplainingeachstep,

providesameanstodifferentiatesystemsthatcanbepermittedquicklyandeasilyduetotheir

similaritywiththemajorityofsmallscalePVsystems.Asmostsystemshaveunique

characteristics,they

may

be

handled

with

small

additions

to

this

expedited

process

or

may

requiremuchmoreinformation,dependingontheuniquenessoftheinstallation.

ThediagramsshownintheExpeditedPermitProcessareavailableonlineatwww.solarabcs.org

inaninteractivePDFformatsothatthediagramscanbefilledoutelectronicallyandsubmitted

eitherinprintedformorviaemailtothelocaljurisdiction.Anelectronicformatisusedsothat

thesuppliedinformationisstandardizedandlegibleforthelocaljurisdiction.Additional

drawingswillbeaddedtothewebsiteastheybecomeavailable.

Theexpeditedprocessdoesprovideforflexibilityinthestructuralreviewincludingspantables

and

additional

information

found

in

Appendix

B

of

this

explanatory

document.

PV

systems

with

batterybackupmaybeabletouseaportionofthisinformationtoassistthepermitting

process,butarrayconfigurationsandthebatterysystemrequireamoredetailedelectrical

drawingthanthisprocessprovides.

TheappendixtothisexplanatorydocumenthasanexamplesubmittalinAppendixAalsohasa

varietyofspecialelectricaltopicsinAppendixC.ItalsoincludestemperaturetablesinAppendix

DthatareusedinapplyingtheNationalElectricalCodestemperaturedependentcriteria.This

documentisintendedtobeusablethroughouttheUnitedStatesandcanprovidestandard

installationdesigndocumentationformostlocationswithintheU.S.andotherregionsthatuse

theNationalElectricalCode.


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ExpeditedPermitProcessforSmallScalePVSystemsTheinformationinthisguidelineisintendedtohelplocaljurisdictionsandcontractorsidentifywhenPVsystem

installationsaresimple,needingonlyabasicreview,andwhenaninstallationismorecomplex.Itislikelythat

50%75%ofallresidentialsystemswillcomplywiththesesimplecriteria.Forprojectsthatfailtomeetthe

simplecriteria,aresolutionstepsmaybesuggestedtoprovideapathtopermitapproval.

RequiredInformation

for

Permit:

1. Siteplanshowinglocationofmajorcomponentsontheproperty.Thisdrawingneednotbeexactlytoscale,butitshouldrepresentrelativelocationofcomponentsatsite(seesuppliedexamplesiteplan).

PVarraysondwellingswitha3perimeterspaceatridgeandsidesmaynotneedseparatefireservice

review.

2. ElectricaldiagramshowingPVarrayconfiguration,wiringsystem,overcurrentprotection,inverter,disconnects,requiredsigns,andacconnectiontobuilding(seesuppliedstandardelectricaldiagram).

3. Specificationsheetsandinstallationmanuals(ifavailable)forallmanufacturedcomponentsincluding,butnotlimitedto,PVmodules,inverter(s),combinerbox,disconnects,andmountingsystem.

Step1:StructuralReviewofPVArrayMountingSystemIsthearraytobemountedonadefined,permittedroofstructure? Yes NoIfNoduetononcompliantrooforagroundmount,submitcompletedworksheetforthestructureWKS1.

RoofInformation:

1. Istheroofingtypelightweight(Yes=composition,lightweightmasonry,metal,etc)_____________If No,submitcompletedworksheetforroofstructureWKS1(No=heavymasonry,slate,etc).

2. Doestheroofhaveasingleroofcovering? Yes NoIfNo,submitcompletedworksheetforroofstructureWKS1.

3. Providemethodandtypeofweatherproofingroofpenetrations(e.g.flashing,caulk).____________MountingSystemInformation:

1. ThemountingstructureisanengineeredproductdesignedtomountPVmodules? Yes NoIfNo,providedetailsofstructuralattachmentcertifiedbyadesignprofessional.

2. Formanufacturedmountingsystems,filloutinformationonthemountingsystembelow:a. MountingSystemManufacturer ___________ProductNameandModel#_____________b. TotalWeightofPVModulesandRails___________lbsc. TotalNumberofAttachmentPoints____________d. WeightperAttachmentPoint(bc)_________________lbs(ifgreaterthan40lbs,seeWKS1)e. MaximumSpacingBetweenAttachmentPointsonaRail______________inches(seeproduct

manualformaximumspacingallowedbasedonmaximumdesignwindspeed)

f. TotalSurfaceAreaofPVModules(squarefeet)_________________ft2g. DistributedWeightofPVModuleonRoof(bf)_______________lbs/ft2

IfdistributedweightofthePVsystemisgreaterthan5lbs/ft2,seeWKS1.

Step2:ElectricalReviewofPVSystem(CalculationsforElectricalDiagram)InorderforaPVsystemtobeconsideredforanexpeditedpermitprocess,thefollowingmustapply:

1. PVmodules,utilityinteractiveinverters,andcombinerboxesareidentifiedforuseinPVsystems.2. ThePVarrayiscomposedof4seriesstringsorlessperinverter,and15kWSTCorless.3. Thetotalinvertercapacityhasacontinuouspoweroutput13,440Wattsorless4. Theacinterconnectionpointisontheloadsideofservicedisconnectingmeans(690.64(B)).5. Theelectricaldiagram(E1.1)canbeusedtoaccuratelyrepresentthePVsystem.

Filloutthestandardelectricaldiagramcompletely.Aguidetotheelectricaldiagramisprovidedtohelpthe

applicantunderstandeachblanktofillin.Iftheelectricalsystemismorecomplexthanthestandardelectrical

diagramcaneffectivelycommunicate,provideanalternativediagramwithappropriatedetail.


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ContractorName,

AddressandPhone:

_____

____________

_____

____________

_____

____________

_____

____________

S

ampleSitePlan

forSmall-Scale,Single-PhasePVSystems

SiteName:___

________________________

SiteAddress:_

________________________

SystemACSize:______________________

SIZE

FSCMNO

DWGNO

REV

S1.1

SCALE

NTS

Date:

SHEET

DrawnBy:

CheckedBy:

INVERTERWITH

SUPPLIED

COMBINERAND

DCDISCONNECT

3'-0"

3'-0"

3'-0"

J

EXISTINGALL-IN-ONE

SERVICEEQUIPMENT

W

ITH40-AMPPV

B

REAKERASAC

DISCONNECT

24SOLARWORLDSW175

MODULESIN2SERIESSTRINGS

OF12MODULESEACHON

EXISTINGROOFSTRUCTURE

ROOFTOPJ-BOXTO

TRANSITIONEXPOSED

USE-2TOTHWN-2

CONDUCTORSIN"EMT

10'-8"

11'-3"

12'-7"

EXISTINGFENCE

24SOLARWORLDSW175


OF12MODULESEACHON

EXISTINGSHADESTRUCTURE

J


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ContractorName,

Address

andPhone:

_______

__________

_______

__________

_______

__________

_______

__________

One-LineStan

dardElectricalDiagramfor

Small-Scale,Single-PhasePVSystems

SiteName:_

________________________

SiteAddress

:_______________________

SystemACS

ize:____________________

SIZE

FSCMNO

DWGNO

REV

E1.1

SCALE

NTS

Date:

SHEET

DrawnBy:

CheckedBy:

DESCRIPTIONORCO

NDUCTORTYPE

USE-2

orPVWIRE

BARECOPPEREQ.G

RD.COND.(EGC)

THWN-2

orXHHW

-2

orRHW-2

THWN-2

orXHHW

-2

orRHW-2

INSULATEDEGC

DCGROUNDINGELE

CTRODECOND.

THWN-2

orXHHW

-2

orRHW-2

INSULATEDEGC

TAG

12345

CONDUITANDCONDUCTORSCHEDULE

COND.

GAUGE

NUMBEROF

CONDUCTORS

CONDUIT

TYPE

N/A

N/A

CONDUIT

SIZE

N/A

N/A

DESCRIPTION

SOLARPVMODULE

PVARRAY

J-BOX(IFUSED)

COMBINER(IFUSED

)

DCDISCONNECT

DC/ACINVERTER

GENMETER(IFUSE

D)

ACDISCONNECT(IF

USED)

SERVICEPANEL

TAG

123456789

PARTNUMBER

NOTES

_____VAC,_

_____AMAIN,______ABUS,______AINVE

RTEROCPD

(SEENOTE5FORINVERTEROCPDs,ALSOSEEGUIDESECTION9)

FORUNUSEDSERIESSTRINGS

PUT"N/AinBLANKABO

VE

SEEGUIDEAPPENDIXB

FOR

INFORMATIONONMODUL

EAND

ARRAYGROUNDING

________MODULES

IN

SERIESSOURCE-CIRC

UIT

________MODULES

IN

SERIESSOURCE-CIRC

UIT

________MODULESIN

SERIESSOURCE-CIRC

UIT

________MODULESIN

SERIESSOURCE-CIRC

UIT

DC

DISCO

INVERTER

A

C

DIS

CO

AC

DC

M

BUILDING

GROUNDING

ELECTRODE

G

Disrega

rdif

providedwith

inverter

COMBINER

MUTILITY

SERVICE

MAINSERVICE

PANEL

MAIN

OCPD

INVERTER

OCPD

J-BOX

1

1

3

4

5

6

7

9

2

3

4

5

8

2

EQUIPMENTSCH

EDULE


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ExpeditedPermitGuidelinesforSmallScalePVSystems

Section1. RequiredInformationforPermit:

1. Siteplanshowinglocationofmajorcomponentsontheproperty.Thisdrawingneednotbe

toscale,butitshouldrepresentrelativelocationofcomponentsatsite.(seesupplied

examplesite

plan).

Explanation:Thisisasimplediagramtoshowwheretheequipmentislocatedontheproperty.

Thiscanbeazoneclearanceplotplanwiththeequipmentclearlyshownandidentifiedontheplan.If

PVarrayisgroundmounted,clearlyshowthatsystemwillbemountedwithinallowablezoned

setbacks. Seesiteplanexampledrawinginpermitprocessforreference.

2. ElectricaldiagramshowingPVarrayconfiguration,wiringsystem,overcurrentprotection,

inverter,disconnects,requiredsigns,andacconnectiontobuilding(seesuppliedstandard

electricaldiagram).

Explanation:Thecornerstoneofasimplifiedpermitprocessistheabilitytoexpresstheelectrical

designwithagenericelectricaldiagram.Thisdiagramhasbeendesignedtoaccuratelyrepresentthe

majorityofsinglephase,residentialsized,PVsystems.PVsystemsmayvarydramaticallyinPVarray

layoutandinverterselection.However,themajorityofsmallscale,residentialsizedPVsystemscanbeaccuratelyrepresentedbythisdiagram.Thisdiagrammustbefullycompletedfilledoutinorder

forthepermitpackagetobesubmitted.

3. Specificationsheetsandinstallationmanuals(ifavailable)forallmanufacturedcomponents

including,butnotlimitedto,PVmodules,inverter(s),combinerbox,disconnects,and

mountingsystem.

Explanation:Ataminimum,specificationsheetsmustbeprovidedforallmajorcomponents.In

additiontothecomponentslisted,otherimportantcomponentsmaybespecialtyfuses,circuit

breakers,oranyotheruniqueproductthatmayneedtobereviewedbythelocaljurisdiction.

Installationmanualsarealsolistedinthisitem.Thisisreferringtothebriefversionsofmanualsthat

arereviewedbythelistingagencycertifyingtheproduct.Somedetailedinstallationmanualscanbe

severaldozensorhundredsofpages.Ifthelocaljurisdictionfeelsitisnecessarytoreviewtheselargedocuments,agoodalternativewouldbeforthedocumentstobesuppliedelectronically,ratherthan

inprint.ItisworthconsiderationthatPDFsofthesecomprehensivemanualsbekeptelectronicallyby

thelocaljurisdiction.

Section2. Step1:StructuralReviewofPVArrayMountingSystem

Isthearraytobemountedonadefined,permittedroofstructure? Yes No(structure

meetsmoderncodes)

IfNo,submitcompletedworksheetforroofstructureWKS1.Explanation:Thereferencetoadefined,permittedroofstructurereferstostructuresthathavea

clearinspectionhistorysothatverificationofstructuralelementsisunnecessary.Ifstructural

modificationshavebeenmadeduetoremodeling,thosechangesshouldbedocumentedthroughthe

permitandreviewprocess.Italsorecognizesthefactthatthecodeenforcementofroofstructural

elementshasbeenmuchmoreconsistentacrosstheUnitedStatesinthelast35years.However,there

maybemanylocaljurisdictionswhohavebeencarefullyreviewingroofstructuresforamuchlonger

periodoftime.Thelocaljurisdictionshouldconsiderextendingthislimitbasedontheperiodthatroofs

havebeenconsistentlyinspected.Inareaswherejurisdictionalreviewshavenotextended35yearsinto


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thepast,thejurisdictionmayneedtogettheinformationfromWKS1tobesurewhetherornotthe

proposedPVsystemisbeinginstalledonatypicalroofstructureornot.

RoofInformation:

1. Istheroofingtypelightweight(Yes=composition,lightweightmasonry,metal,wood

shake,etc)_____________

If No,submitcompletedworksheetforroofstructureWKS1(No=heavymasonry,slate,

etc).

Explanation:Thereisaneedtodistinguishifaroofhasalightweightproduct.Heavier

roofingmaterials(e.g.slate,heavymasonry,maynothavetheassumeddeadloadingandlive

loadingcapacitiesthatarefoundwithlighterweightroofingmaterials.Thesearemuchless

commonrooftypesandoftenjustifyafurtherreviewtoclarifythattheroofstructureiseitherin

complianceorneedsenhancement.

2. Doestheroofhaveasingleroofcovering? Yes No

IfNo,submitcompletedworksheetforroofstructureWKS1.Explanation:Multiplecompositionrooflayersaretakingaportionoralloftheassumed

additionalweightallowancefoundinthe5lbs/ft2allowanceattheendofthemountingsystem

section.

3. Providemethodandtypeofweatherproofingroofpenetrations(e.g.flashing,

caulk).____________

Explanation:Theweatherproofingmethodneedstobespecificallyidentifiedsothatplan

checkersandfieldinspectorsarenotifiedaheadoftimeofthemethodbeingused.Some

jurisdictionsmayconstrainweatherproofingmethodsandmaterials.

MountingSystem

Information:

1. ThemountingstructureisanengineeredproductdesignedtomountPVmodules?Yes No

IfNo,providedetailsofstructuralattachmentcertifiedbyadesignprofessional.Explanation:Nonengineeredrackingsystemshaveundefinedcapabilities.PVsystems

shouldonlybemountedusingsystemsthatareengineeredanddesignedforthatpurpose.

However,ifaninstallerchoosestouseahybridmountingsystem,thenthesystemcannotbe

consideredforexpeditedpermitting.

2. Formanufacturedmountingsystems,filloutinformationonthemountingsystem

below:

a. MountingSystem

Manufacturer

___________Product

Name

and

Model#_____________(selfexplanatory)

b. TotalWeightofPVModulesandRails___________lbs(includetotalweightofall

hardwareusedalongwithmoduleweight)

c. TotalNumberofAttachmentPoints____________(selfexplanatory)

d. WeightperAttachmentPoint(bc)_________________lbs(ifgreaterthan40

lbs,seeWKS1)


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Explanation:40lbshasbeenusedbymanyjurisdictionsasareasonablelevelbelow

whichpointloadingofroofjoistsandtrussescanbeignored.Moststandardmounting

systemshavepointloadingsof2535lbsperattachment.

e. MaximumSpacingBetweenAttachmentPointsonaRail______________inches

(seeproductmanualformaximumspacingallowedbasedonwindloading)

Explanation:

Depending

on

the

wind

loading

requirements

of

a

particular

jurisdiction,

thespacingorattachmentsmaybedictatedbythemanufacturersdirections.Forinstance,a

particularmanufacturermayallowa72attachmentspacingfora90MPHwindspeed

design,butthespacingreducestoamaximumof48whenthedesignwindspeedexceeds

100MPH.

f. TotalSurfaceAreaofPVModules(squarefeet)_________________ft2Explanation:Takethesurfaceareaofasinglemodule,andmultiplyitbythetotal

numberofmodulesintheroofmountedsystem.

g. DistributedWeightofPVModuleonRoof(bf)_______________lbs/ft2


Explanation:The5lbs/ft2limitisbasedontwothings:1)theroofistypicalofstandard

codecompliantroofstructuressothatthestructureeitherhastheproperspansandspacing,

orproperuseofengineeredtrusses(firstitemunderStep1:StructuralReview);and,2)

thereisasinglelayerofroofingsothatthenormalweightallowanceforadditionalroof

layersisunusedandavailablefortheweightofthePVsystem.Forapplicationson

lightweightmasonryroofingmaterialsandotherlightweightroofingproducts(e.g.metal,

shake,etc),thesematerialsdonotacceptmultiplelayersandthereforethe5lbs/ft2

allowanceisusedtoidentifythemaximumallowableadditionalweightforroofsthatare

exchangingtheallowableliveloadforadeadloadthatpreventsliveloadsuchaspeople

walkingontheroof.

Section3. Step2:ElectricalReviewofPVSystem(CalculationsforElectricalDiagram)

InorderforaPVsystemtobeconsideredforanexpeditedpermitprocess,thefollowingmustapply:

1. PVmodules,utilityinteractiveinverters,andcombinerboxesareidentifiedforuseinPV

systems.

Explanation:PVutilityinteractiveinvertersmustbespecificallylistedandlabeledforthis

application(asrequiredbyNEC690.60and690.4)(Numbersinbracketsrefertosectionsinthe2008

NECthroughoutthisdocument.).Withoutthisspecificidentificationprocessanunacceptable

amountofreviewwouldbenecessarytoapproveaninverter.InvertersthatpassUL1741andare

listedasutilityinteractivehavemettherequirement.Over500inverterscurrentlymeetthis

requirement.Aninclusivelistoftheseinvertersisavailableonlineat

http://gosolarcalifornia.com/equipment/inverter.php.

PVmodulesmustalsobelistedandidentifiedforuseinPVsystems(asrequiredbyNEC690.4).PV

modulesthatpassUL1703andhavea600Voltmaximumvoltagemeettherequirement.Alistof

theseinvertersisavailableonlineathttp://gosolarcalifornia.com/equipment/pvmodule.php.Source

combinersmustbelistedandlabeledtomeetthedcvoltagerequirementsofthePVsystemorbe

specificallytestedforPVsystemsandclearlystatetheallowablemaximumcurrentandvoltage(as

requiredbyNEC690.4).


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2. ThePVarrayiscomposedof4seriesstringsorless,and15kWSTCorless.Explanation:Thepurposeofthisrequirementistolimitthenumberofoptionsofwhatcan

complyasasimplesystemsothatasingleelectricaldiagramcanbeusedtodescribealarge

portionofthesystemsbeinginstalled.Theelectricaldiagramcanhandleupto4stringsinparallel.

Themaximumof15kWreferstothearraysizebasedonthetotalinstallednameplatecapacity.The

limitissettostaygenerallywithinelectricalinterconnectionsthatwouldbeconsideredsimpleand

possiblyabletomeetthe120%ofbusbarratingallowanceinNEC690.64(B)inaresidence

(Minimumbreakerfora13.44kWacPVsystemis70amps).

3. TheInverterhasacontinuouspoweroutput13,440WattsorlessExplanation:A70ampbreakerisimportantsincea225ampbusbarina200amppanelwill

allowa70ampPVbreaker.Sincethisdoeshappenfromtimetotime,andaninstallercanchooseto

installsuchapanelboard,itisconsideredthelargestsimplePVsystemforpurposesofthis

guideline.Atableofbreaker/panelboardcombinationsisinSection9ofthisGuideline.

4. Theacinterconnectionpointisontheloadsideofservicedisconnectingmeans(NEC

690.64(B)).

Explanation:Loadsideinterconnectionsarebyfarthemostcommon,particularlyinresidential

applications.AnylinesideconnectioniscoveredbyNEC690.64(A)and230.82.Althoughlineside

connectionscanbequitestraightforward,theyshouldrequireanadditionalstepintheapproval

processandrequireaslightlydifferentelectricaldrawing.

5. Theelectricaldiagram(E1.1)canbeusedtoaccuratelyrepresentthePVsystem.Explanation:Thebasisforasimplifiedpermitistheuseofthestandardelectricaldiagram.

Clearly,PVsystemscanvarysignificantlyinPVarraylayoutandinverterselection.However,the

majorityofsmallscale,residentialsizedPVsystemscanbeaccuratelyrepresentedbythisdiagram.

Thisdiagrammustbecompletelyfilledoutinorderforthepermitpackagetobeconsidered

complete.Thisdiagramisnotintendedforusewithbatterybasedsystems.

Section4. InverterInformation

Acopyofthemanufacturersspecificationsheetisrequiredforapermitsubmittal.Inaddition,

aprintedoutdigitalphotooftheinverterlistinglabelcanbeveryhelpfulforgatheringthe

ratingsoftheequipment.Aprerequisiteforacodeapprovedinstallationistheuseofalisted

inverter[NEC690.4;690.60].TodetermineifaninverterislistedbyaNationallyRecognized

TestingLaboratory(NRTL)toULStd.1741,thelistinglabelcanbeexaminedtoseeifitislabeled

UtilityInteractive.Iftheutilityinteractivelabelingisnotprovided,doestheunitcomplywith

therequirementsofIEEEStd.1547asverifiedtheinstructionmanualsvalidatedbythelisting

agency.For

acurrent

list

of

compliant

inverters,

visit

the

GoSolarCalifornia

website

at

http://gosolarcalifornia.com/equipment/inverter.php.SomeNRTLshavecurrentlisting

informationonlineaswell.

a) INVERTERMAKE:Thisisthemanufacturersname:(e.g.PVPowered,SMA,etc)

b) INVERTERMODEL#:Thisisthemodelnumberonthelistinglabel:(e.g.PVP5200,

SB7000US,etc)


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12

c) MAXDCVOLTAGERATING:Providedeitheronlistinglabelorspecificationsheet.

d) MAXPOWER@40C:Themaximumcontinuousoutputpowerat40

Cisrequired

informationforthelistinglabelandtheGoSolarCaliforniawebsite.Ifthespecification

sheetdoesnotclearlystatethevalue,consulteitheroftheseothertwosources.

e) NOMINALACVOLTAGE: Thisistheacoutputvoltageoftheinverterasconfiguredfor

thisproject.

Some

inverters

can

operate

at

multiple

ac

voltages.

f) MAXOCPDRATING:Thisisthemaximumovercurrentprotectivedevice(OCPD)rating

allowedfortheinverter.Thisiseitherstatedonthelistinglabelorintheinstallation

manual.Sometimesthisisalsolistedonthespecificationsheetbutnotalways.Itis

importanttocheckthattheinverterOCPDratinginthepanelislessthanorequaltothis

maximumratingtopreservethelistingoftheinverter.

Section5. ModuleInformation

Acopyofthemanufacturersspecificationsheetisrequiredforapermitsubmittal.Inaddition,

aprintedoutdigitalphotoofthemodulelistinglabelcanbeveryhelpfulforgatheringthe

ratingsoftheequipment.Aprerequisiteforacodeapprovedinstallationistheuseofalisted

PVmodules[NEC690.4]toUL1703.ForacurrentlistofmodulesthatarelistedtoUL1703,

visittheGoSolarCaliforniawebsite,http://gosolarcalifornia.com/equipment/pvmodule.php.Explanation:Thismoduleinformationisparticularlyimportantsinceitisusedtocalculate

severalcurrentandvoltageparametersrequiredbytheNationalElectricalCode(NEC).Listing

informationisnecessaryforNECtestingrequirements[90.7,100,110.3,690.4].(Numbersin

bracketsrefertosectionsinthe2008NECthroughoutthisdocument.)

a) MODULEMANUFACTURER: Thisisthemanufacturersname:(e.g.Evergreen,

SunPower,etc)

b) MODULEMODEL#:Thisisthemodelnumberonthelistinglabel:(e.g.EGS185,SP225,

etc)c) MAXIMUMPOWERPOINTCURRENT(IMP)

Explanation:TheratedIMPisneededtocalculatesystemoperatingcurrent.Thisisthecurrent

ofthemodulewhenoperatingatSTCandmaximumpower.

d) MAXIMUMPOWERPOINTVOLTAGE(VMP)Explanation:TheratedVMPisneededtocalculatesystemoperatingvoltage.Thisisthe

voltageofthemodulewhenoperatingatSTCandmaximumpower.

e) OPENCIRCUITVOLTAGE(VOC)Explanation:TheratedVOCisneededtocalculatedmaximumsystemvoltagespecifiedinNEC

690.7.

f) SHORTCIRCUITCURRENT(ISC)

Explanation:TheratedISCisneededtocalculatemaximumcurrentspecifiedinNEC690.8(A).g) MAXIMUMSERIESFUSE(OCPD)

Explanation:Maximumseriesfuse(OCPD)ratingisneededtoensurethattheproper

overcurrentprotectionisprovidedforthemodulesandarraywiring.

h) MAXIMUMPOWER(PMAX)atStandardTestConditions(STCis1000W/m2,25

Ccelltemp,

&AirMass1.5)

Explanation:MaximumpoweratSTCspecifiestheratedpowerofthePVmoduleunder

simulatedconditions.


14/51

13

i) MAXIMUMSYSTEMVOLTAGEExplanation:Maximumsystemvoltage(often600Vdc)isneededtoshowthattheNEC690.7

voltagedoesnotexceedthisvalue.

Section6. Arrayinformation

Thissection

defines

the

configuration

of

the

PV

array.

PV

arrays

are

generally

made

up

of

severalmodulesinseries,calledsourcecircuits.Thesesourcecircuitsareoftenparalleledwith

multipleothersourcecircuitstomakeuptheentiredcgeneratingunitcalledthearray.Thelast

fouritemsrelatedtothePVarraymustbecalculatedandpostedonasignatthePVPower

Sourcedisconnect.Thefirsttwoitemsa)andb)characterizethearraydesignandprovidesthe

informationnecessarytocalculatethefouritemsneededtoproduceproperarrayidentification

forPVPowerSourcesigndiscussedinSection7thatisrequiredatthesite.

a) NUMBEROFMODULESINSERIESExplanation:Forsimplicity,thisdiagramonlyaddressesthemostcommonconfigurationofPV

modulesmultiplemodulesinseries.AlthoughsinglemodulePVpowersourcesexist,itismorecommon

toseePVarraysconfiguredwithasmanyas12or16modulesinseries.

b) NUMBEROFPARALLELCIRCUITSExplanation:Sincesinglephaseinverterscanbeaslargeas12kWormore,andthelargestPV

sourcecircuitsareonly2or3kW,itiscommonforPVarraystohavetwoormoresourcecircuitsin

parallel.FromExampleinAppendixOne:

Numberofmodulesinseries=12

Numberofparallelsourcecircuits=4

Totalnumberofmodules=12x4=48

c) LOWESTEXPECTED

AMBIENT

TEMP

Explanation:Upthroughthe2008edition,theNEChasnotclearlydefinedlowestexpectedambient

temperature.ASHRAE(AmericanSocietyofHeating,Refrigeration,andAirConditioningEngineers)has

performedstatisticalanalysisonweatherdatafromtheNationalWeatherService.Thesedatainclude

valuesforthemeanextremetemperaturesforthelocationswithtemperaturedata.Themeanextreme

lowtemperatureisthecoldestexpectedtemperatureforalocation.Halfoftheyearsonrecordhavenot

exceededthisnumber,andtheresthaveexceededthisnumber.Thesedataaresuppliedintheappendix

forreference.Aproposalislikelytoacceptedforthe2011NEC toincludeaFinePrintNoteto690.7that

specifiestheuseoftheASHRAEmeanextremevalueforlowestexpectedambienttemperature.

d) HIGHESTCONTINUOUSTEMP(ambient)

Explanation:Upthroughthe2008edition,theNEChasnotclearlydefinedhighestcontinuousambienttemperature.ContinuousisdefinedintheNECasa3hourperiod(Article100).ASHRAE

(AmericanSocietyofHeating,Refrigeration,andAirConditioningEngineers)hasperformedstatistical

analysisonweatherdatafromtheNationalWeatherService.Thesedataincludedesignvaluesof0.4%,

1%,and2%foreachmonthsignifyingthatthetemperatureonlyexceedstherecordedvalueupto2%of

thetimeforagivenlocationwithtemperaturedata.The2%valuehasbeenchosenbytheCopper

DevelopmentInstituteasthevaluethatbestrepresentsaconditionthatwouldcreatethe3hour

continuousconditionreferredtoinArticle100.Twopercentofonemonthisabout14hours.Sincehigh


15/51

14

temperaturesusuallylastforseveraldaysinmostlocations,theassumptionisthatatleastoneortwo3

hourhightemperatureeventswillhappenduringagivenmonth.Thesedataaresuppliedintheappendix

forreference.Aproposalforthe2011NEChasbeensubmittedtoincludeaFinePrintNotetoTable

310.16thatspecifiestheuseoftheASHRAE2%dataforthehottestmonthtodeterminehighest

continuousambienttemperature.

Section7. SIGNS

a) PVPOWERSOURCE

i) RATEDMPP(MAXIMUMPOWERPOINT)CURRENT

(sumofparallelsourcecircuitoperatingcurrents)

Explanation:RatedMPPcurrentisfoundbymultiplyingthemoduleratedMPPcurrentfora

moduleseriesstringbythenumberofsourcecircuitsinparallel.

FromtheexampleinAppendixOne:

IMP=4.89amps

Numberofsourcecircuitsinparallel=44.89ampsx4=19.6amps

ii) RATEDMPP(MAXIMUMPOWERPOINT)VOLTAGE

(sumofseriesmodulesoperatingvoltageinsourcecircuit)

Explanation:OperatingvoltageisfoundbymultiplyingthemoduleratedMPPvoltagebythe

numberofmodulesinaseriessourcecircuit.


VMP=35.8Volts

Numberofmodulesinseries=12

35.8Voltsx12=430Volts

iii) MAXIMUMSYSTEM

VOLTAGE

[NEC

690.7]

Explanation:MaximumsystemvoltageiscalculatedbymultiplyingthevalueofVoconthe

listinglabelbytheappropriatevalueonTable690.7intheNEC,andthenmultiplyingthatvalue

bythenumberofmodulesinaseriesstring.ThetableintheNECisbasedoncrystallinesilicon

modulesanduseslowestexpectedambienttemperatureatasitetoderivethecorrectionfactor.

Somemodulesdonothavethesametemperaturecharacteristicsascrystallinesiliconsothe

manufacturersinstructionsmustbeconsultedtodeterminetheproperwaytocorrectvoltage

basedonlowestexpectedambienttemperature.


ModuleVOC=44.4Volts

NumberofModulesinSeries=12

Lowestexpectedambienttemperature(ASHRAE)=0C(SanJose,California)

Method1NECTable690.7:

MaximumSystemVoltage=VMAX=VOCxNo.ofModulesinSeriesxTable690.7Value

VMAX=44.4Vx12x1.10=586Volts


16/51

15

PercentageMethod:

VMODMAX=VOC+VOCx VOC(%)x(TempLOWTempRATED)

VoltageMethod:

VMODMAX=VOC+ VOC(V)x(TempLOWTempRATED)

MaximumSystemVoltage=VMAX=VMODMAXxNumberofModulesinSeries

MaximumSystemVoltage=VMAX

=44.4V+44.4Vx0.0033/Cx(0C 25C)x12

VMAX=[44.4V+44.4Vx0.0033/Cx(25C)]x12=577Volts


17/51

16

Section8. WiringandOvercurrentProtection

a) DCWiringSystems:

Sourcecircuit

conductors:

InExposedLocations:

PVmoduleinterconnectionsaregenerally90Cwetratedconductors(NEC690.31(A)

FPN).Thesameconductortypeistypicallyusedforallhomerunconductorsneeded

forsourcecircuitconductorsinexposedlocations.

Allowablewiretypesareasfollows:

USE2singleconductorcableforexposedlocations.[NEC690.31(B)]

PVWireorPVCableasasingleconductorforexposedlocations(requiredforall

ungroundedsystems).[NEC690.31(B)]ExplanationfortheneedforHighTemperatureConductors:Typicaltemperature

forPVmodulesinfullsunat20Coutdoortemperatureis50C.Thisisa30Criseabove

outdoortemperatures.Onthehottestdayoftheyear,outdoortemperaturescanreacha

continuoustemperatureof41CinmanyhotlocationsthroughouttheUnitedStates.This

meansthatthePVmodulecouldbeoperatingat71Conthehottestdayoftheyear

(41C+30C=71C).75CwireisinsufficientforconnectiontoahotPVmoduleunderthis

condition.

TofurthersupporttheconcernoverthehightemperatureofPVmodules,afineprint

notehasbeenaddedtothe2005NEC.

NEC690.31(A)FPN: Photovoltaicmodulesoperateatelevatedtemperatureswhen

exposedtohighambienttemperaturesandtobrightsunlight.Thesetemperaturesmay

routinelyexceed70C(158F)inmanylocations.Moduleinterconnectionconductorsare

availablewithinsulationratedforwetlocationsandatemperatureratingof90C

(194F)orgreater.

InConduitonRooftops:

TWOOPTIONSFORSOURCECIRCUITCONDUCTORTYPE(INSIDECONDUITCIRCLE

ONE)THWN2andXHHW2

Explanation:Conductorsinconduit,whenexposedtodirectsunlight,mustaccountfor

thehighertemperaturescausedbyintensesunlightandtheproximityoftheroof.The2005

NECfirstrecognizedtheissueofsunlitconduitinafineprintnoteinNEC310.10.

310.10FPNNo.2:Conductorsinstalledinconduitexposedtodirectsunlightinclose

proximitytorooftopshavebeenshown,undercertainconditions,toexperiencea

temperatureriseof17C(30F)aboveambienttemperatureonwhichtheampacityis

based.

The2008NECcodifiedthisissuebyclassifyingthetemperaturesbasedontheheightabove

theroofsurface.Onresidentialroofs,whereconduittypicallyisspacedbetweenand3

abovetheroofsurface,thetemperatureadderisstatedas22Cabovetheambient

temperatureaccordingtoNECTable310.15(B)(2)(c).Usingthisadder,alongwiththe


18/51

17

ASHRAE2%designdataforthehottestlocationintheU.S.(PalmSprings,CAis44C),

producesadesigntemperatureof66C.andcorrectionfactorof0.58for90Cconductors

basedonNECTable690.31andTable310.16.Ifnineconductorsorlessareintheexposed

conduit(4pairsofconductorsorless),thentheconduitfillcorrectionfactoris0.7according

toNECTable310.15(B)(2)(a).Puttingallthesecorrectionfactorstogethermeansthatthe

30C.conductorampacitymustbeasfollows:

Ifonlytwostringsinparallel(nofuses):

I30C.=IMAX/0.58/0.7=2.46xIMAX

IfISC=9.6ampsorless,thenIMAX=ISCx1.25=12ampsorless.

IfIMAX=12Amps,thenI30C.=29.5Amps(12AWG,90Crequired(NECTable310.16))

IfISC=6.4ampsorless,thenIMAX=ISCx1.25=8ampsorless.

IfIMAX=8Amps,thenI30C.=19.7Amps(14AWG,90Crequired(NECTable310.16))

IffusesareneededtoprotectPVmodules(mostcases):

I30C.=IFUSE/0.58/0.7=2.46xIFUSE

IfISC=9.6ampsorless,thenIMAX=ISCx1.25=12amps.Theminimumovercurrent

protectivedevice(OCPD)asrequiredby690.8(B)is15amps(IFUSE=IMAXx1.25=15A).

IfIFUSE=15Amps,thenI30C.=2.46x15A=36.9Amps(10AWG,90Crequired(NEC

Table310.16)15Afusetoprotecttheconductor)

IfISC=7.68ampsorless,thenIMAX=ISCx1.25=9.6amps.Theminimumovercurrent

protectivedevice(OCPD)asrequiredbyNEC690.8(B)is12amps(IFUSE=IMAXx1.25=

12A).



IfISC=6.4ampsorless,thenIMAX=ISCx1.25=8amps.Theminimumovercurrent

protectivedevice(OCPD)asrequiredby690.8(B)is10amps(IFUSE=IMAXx1.25=10A).



Maximum

ModuleISC

RequiredFuse

Size

MinimumConductorSize

inConduit(9conductors)

MinimumConductorSizein

FreeAir(atmodules)

9.6Amps 15Amps 10AWG 10AWG



SincethehighestISCmodulecommonlyavailableasofthewritingofthisguideislessthan9

amps,10AWGconductorswillalwaysworkregardlessoflocationintheU.S.aslongasthere


19/51

18

arenomorethan9currentcarryingconductorsintheconduitandtheconduitisatleast0.5

abovetheroofsurface.SmallerwirecanbeusedaccordingtotheISCofthemodulesbeing

usedandthenumberofconductorsintheconduit.Thesecalculationsareprovidedsothat

contractorsandjurisdictionswillnotneedtorepeatthesestandardcalculationsoverand

over.Asimpletablesummarizestheminimumconductorsizes.

b) ACWiringSystems

InverterOutputCircuitovercurrentprotectionshouldbesizedandprotectedaccordingthe

manufacturersdirections.Thecircuitandcorrespondingovercurrentprotectionshouldbe

sizedata125%ofthemaximumcontinuousoutputoftheinverter[NEC215.3Overcurrentfor

FeederCircuits,andNEC690.8(A)(3)and690.8(B)].The125percentincreaseoverthe

maximumInverterOutputCircuitcurrentistoaccountforthestandardlistingofovercurrent

devicesto80%ofmaximumcircuitcurrentforcontinuousduty.Theinvertermayalsohavea

maximumallowableovercurrentrequirement.

Explanation:Forinstance,theSMASB7000UShasamaximumcontinuousoutputof29.2amps

andamaximumallowableovercurrentprotectionof50amps.Thismeansthattheminimumallowableovercurrentis40amps(29.2ampsx1.25=36.5ampsrounduptothenextstandardsize,whichis40

amps)andamaximumof50amps.Normallytheminimumallowablebreakersizeisusedsincethe

panelboardsupplybreakersareconstrainedto120%ofthepanelboardbusbarrating.


Invertercontinuousoutputrating=7000Watts

Nominalinvertervoltage=240Volts

Maximumoperatingcurrent=7000Watts/240Volts=29.2Amps

Min.InverterOutputCircuitampacity=29.2Ampsx1.25=36.5Amps

Section9. ACPointofConnection

NEC690.64(B)coverstherequirementsforPointofConnectionofthePVinvertertothe

buildingelectricalsystem.Themostcommonmethodofconnectionisthroughadedicated

circuitbreakertoapanelboardbusbar.Thesumofthesupplybreakersfeedingthebusbarofa

panelcanbeupto120%ofthebusbarrating.AppendixBtreatsthissubjectindetail.

Explanation:Aservicepanelcontaininga200ampbusbaranda200ampmainbreakerwill

allowbreakerstotaling120%ofthebusbarrating(240amps).Sincethemainbreakeris200amps,the

PVbreakercanbeupto40ampswithoutexceedingthe120%allowance.Foraservicepanelwitha125

ampbusbaranda100ampmainbreaker,thisprovisionwillallowuptoa50ampbreaker(125ampsx

1.2=150amps;150amps100ampmainbreaker=50ampPVbreaker).

Aprovision

in

the

2005NEC

clarifies

the

fact

that

dedicated

circuit

breakers

backfed

from

listed

utilityinteractiveinvertersdonotneedtobeindividuallyclampedtothepanelboardbusbars.

Thishasalwaysbeenthecase,butmanyinspectorshaveemployedtheprovisionsofNEC

408.36(F)thatthebreakerbesecuredinplacebyanadditionalfastener.Utilityinteractive

invertersdonotrequirethisfastenersincetheyaredesignedtoshutdownimmediatelyshould

thededicatedbreakerbecomedisconnectedfromthebusbarunderanycondition.This

provisionisrepeatedinthe2008NECinaclearandconcisestatement:


20/51

19

NEC690.64(B)(6)Fastening.Listedplugintypecircuitbreakersbackfedfromutilityinteractiveinverterscomplyingwith690.60shallbepermittedtoomittheadditionalfastenernormally

requiredby408.36(D)forsuchapplications.

NEC690.64(B)coverstherequirementsforPointofConnectionofthePVinvertertothe

buildingelectrical

system,

which

is

the

most

common

method

of

connection.

The

table

below

showsthehowthemaximumcurrentoftheinverter(column1)requiresaminimumsizeOCPD

(column2),whichrequiresaminimumsizeconductor(column3),whichrequiresacompatible

busbar/mainbreakercombinationinthepanelboard(column4).Thewaytounderstand

column4,minimumbusbar/mainbreakercombinationsistolookattherowthatcoincideswith

theparticularbreakerbeingselected(fromcolumn2)anduseanycombinationfromcolumn4

foundonthatroworhigherinthetable.Forinstance,a40Ampsinverterbreakerworkswitha

200/200panelcombination,butitalsoworkswitha125/100combinationfoundontherow

above.The40Ampbreakerdoesnotworkonthe150/150combination,sincethelargest

breakerwouldbe30ampsforthe150/150combination.

TableofNEC690.64(B)ACInterconnectionOptionsMaximum

Inverter

Current

Required

InverterOCPD

Size

Minimum

ConductorSizein

Conduit

MinimumBusbar/MainBreaker

Combinations

(BusbarAmps/MainAmps)

64Amps 80Amps 4AWG 400/400;200/150

56Amps 70Amps 4AWG 225/200;250/225

48Amps 60Amps 6AWG 300/300;200/175

40Amps 50Amps 8AWG 125/100;150/125

32Amps 40Amps 8AWG 225/225;200/200;150/125

24Amps

30

Amps

10

AWG

150/150

16Amps 20Amps 12AWG 100/100;70/60

12Amps 15Amps 14AWG 80/80

Section10. Grounding

a) SystemGrounding

TheNECrequires[690.41]thatallsystemsoperatingabove50voltshaveoneconductor

referencedtogroundunlessthesystemcomplieswiththerequirementsofNEC690.35for

ungroundedPVarrays.

b) EquipmentGrounding

Thecodealsorequiresthatallexposednoncurrentcarryingmetalpartsofmoduleframes,

equipment,andconductorenclosuresbegroundedregardlessofsystemvoltage[NEC690.43].

Thegroundingofmoduleframeshasreceivedsignificantattentioninthelastseveralyears.

Manyjurisdictions,withaheightenedconcernovertheissue,havedramaticallyrestricted

effectivegroundingoptions. AdiscussiononmoduleframegroundingisfoundintheAppendix.


21/51

20

c) SizingofGroundingConductors

i) Equipmentgroundingconductor(EGC)sizing[NEC690.45]

ThesizeoftheEGCisdependentonwhetherthesystemhasgroundfaultprotection

(GFP)equipmentornot.TheprovisionsforGFPequipmentarestatedinNEC690.5.

Almostall

inverters

have

GFP

equipment

integral

to

the

inverter

and

require

that

the

PV

arraybegroundedattheinverteronly.

(1)Systemswithgroundfaultprotectionequipment

SizeequipmentgroundingconductoraccordingtoNECTable250.122.

(2)Systemswithoutgroundfaultprotectionequipment

TheNECrequiresthatequipmentgroundingconductorsforsystemswithoutGFP

equipmentbesizedfortwicethecircuitshortcircuitcurrent[NEC690.45].

ii) Systemgroundingconductorsizing

(1)ACSystem

Sizegroundingelectrodeconductor(GEC)accordingtoNECTable250.66.

Normallythesitealreadyhastheconductorandelectrodeinstalledfortheac

buildingwiring.

(2)DCSystem

Sizegroundingelectrodeconductor(GEC)accordingtoNEC250.166.Thisresults

inaminimumsizeof8AWG.ThemaximumsizeoftheGECisdependentupon

thetypeofgroundingelectrodeorthemaximumsizeconductorinthesystem,

whicheverissmaller.


22/51

21

APPENDIX


23/51

22

APPENDIXA:EXAMPLESUBMITTAL

Step1:StructuralReviewofPVArrayMountingSystem

Isthearraytobemountedonadefined,permittedroofstructure? Yes No

(structuremeetsmoderncodes)

IfNoduetononcompliantrooforgroundmount,submitcompletedworksheetforroofstructureWKS1.

RoofInformation:

1. Istheroofingtypelightweight(Yes=composition,lightweightmasonry,metal,etc)_Yescomposition

If No,submitcompletedworksheetforroofstructureWKS1(No=heavymasonry,slate,etc).

2. Doestheroofhaveasingleroofcovering? Yes No

IfNo,submitcompletedworksheetforroofstructureWKS1.

3. Providemethodandtypeofweatherproofingroofpenetrations(e.g.flashing,caulk).__flashing_____

MountingSystemInformation:

1. ThemountingstructureisanengineeredproductdesignedtomountPVmodules? Yes NoIfNo,providedetailsofstructuralattachmentcertifiedbyadesignprofessional.

2. Formanufactured

mounting

systems,

fill

out

information

on

the

mounting

system

below:

a. MountingSystemManufacturer_UniRac_ProductNameandModel#__SolarMount___

b. TotalWeightofPVModulesandRails___1780________lbs

c. TotalNumberofAttachmentPoints____48___

d. WeightperAttachmentPoint(bc)____37___________lbs(ifgreaterthan40lbs,seeWKS1)

e. MaximumSpacingBetweenAttachmentPointsonaRail______48______inches(seeproduct

manualformaximumspacingallowedbasedonmaximumdesignwindspeed)

f. TotalSurfaceAreaofPVModules(squarefeet)_____674____________ft2

g. DistributedWeightofPVModuleonRoof(bf)______2.64______lbs/ft2


Step2:ElectricalReviewofPVSystem(CalculationsforElectricalDiagram)InorderforaPVsystemtobeconsideredforanexpeditedpermitprocess,thefollowingmustapply:

1. PVmodules,utilityinteractiveinverters,andcombinerboxesareidentifiedforuseinPVsystems.

2. ThePVarrayiscomposedof4seriesstringsorless,and15kWSTCorless.

3. TheInverterhasacontinuouspoweroutput13,440Wattsorless

4. Theacinterconnectionpointisontheloadsideofservicedisconnectingmeans(690.64(B)).

5. Theelectricaldiagram(E1.1)canbeusedtoaccuratelyrepresentthePVsystem.

Filloutthestandardelectricaldiagramcompletely.Aguidetotheelectricaldiagramisprovidedtohelpthe

applicantunderstandeachblanktofillin.Iftheelectricalsystemismorecomplexthanthestandardelectrical

diagramcaneffectivelycommunicate,provideanalternativediagramwithappropriatedetail.


24/51

ContractorName,

AddressandPhone:

Billa

ndTedsSolar

456IndustrialDrive

SanJose,CA

40

8-555-1212

Bill

Ted

SitePlan


SiteName:JoeandJaneHomeowner

SiteAddress:123SunnysideSt.,SanJose,CA

SystemACS

ize:6.9kWSolarArray

SIZE

FSCMNO

DWGNO

REV

S1.1

0

SCALE

NTS

Date:

SHEET

DrawnBy:

CheckedBy:

INVERTERWITH

SUPPLIED

COMBINERAND

DCDISCONNECT

3'-0"

3'-0"

3'-0"

J

EXISTINGALL-IN-ONE

SERVICEEQUIPMENT

W

ITH40-AMPPV

B

REAKERASAC

DISCONNECT

24SOLARWORLDSW175


OF12MODULESEACHON

EXISTINGROOFSTRUCTURE

ROOFTOPJ-BOXTO

TRANSITIONEXPOSED

USE-2TOTHWN-2

CONDUCTORSIN"EMT

10'-8"

11'-3"

12'-7"

EXISTINGFENCE

24SOLARWORLDSW175


OF12MODULESEACHON

EXISTINGSHADESTRUCTURE

J


25/51

ContractorName,

AddressandPhone:

Billa

ndTedsSolar

456IndustrialDrive

SanJose,CA

40

8-555-1212

Bill

Ted

One-LineStandardElectricalDiagram


SiteName:JoeandJaneHomeowner

SiteAddress:123SunnysideSt.,SanJose,CA

SystemACS

ize:6.9kWSolarArray

SIZE

FSCMNO

DWGNO

REV

E1.1

0

SCALE

NTS

Date:

SHEET

DrawnBy:

CheckedBy:

DESCRIPTIONORCO

NDUCTORTYPE

USE-2

orPVWIRE

BARECOPPEREQ.G

RD.COND.(EGC)

THWN-2

orXHHW

-2

orRHW-2

THWN-2

orXHHW

-2

orRHW-2

INSULATEDEGC

DCGROUNDINGELE

CTRODECOND.

THWN-2

orXHHW

-2

orRHW-2

INSULATEDEGC

TAG

12345

CONDUITANDCONDUCTORSCHEDULE

COND.

GAUGE

10AWG

10AWG

10AWG

N/A

N/A

6AWG

8AWG

10AWG

NUMBEROF

CONDUCTORS

8BLACK

1BARECU

4-R,4-W,1-G

N/A

N/A

1BARECU

1-R,1-B,1-W

1GREEN

CONDUIT

TYPE

N/A

N/A

EMT

N/A

N/A

EMT

CONDUIT

SIZE

N/A

N/A

"

N/A

N/A

"

DESCRIPTION

SOLARPVMODULE

PVARRAY

J-BOX(IFUSED)

COMBINER(IFUSED

)

DCDISCONNECT

DC/ACINVERTER

GENMETER(IFUSE

D)

ACDISCONNECT(IF

USED)

SERVICEPANEL

TAG

123456789

PARTNUMBER

SW175mono

N/A

SMA-supplied

SMA-supplied

SB7000US

FORM2S

D222NRB

SD200SL

NOTES

SOLARWOR

LD,QUANTITY-36(SEENOTESSHEETFORDETAILS)

ARRAYIS4

STRINGSWITH12MODULESPERSERIES

STRING

NEMA4,PVCJUNCTIONBOX

15-AMAXFUSEW/15-AFUSES,600VDC,4-STRINGMA

X

LISTEDWITHINVERTER,600VDC,60-AMP(SEEGUIDE

APPENDIXB)

SMA7000W

ATT,SINGLEPHASE(SEENOTESSHEETFORDETAILS)

GENERALE

LECTRIC4-JAW

SQUARED,

240VAC,60-AMPFUSED(SEEGUIDEAPPE

NDIXB)

240VAC,200

-AMAIN,200-ABUS,40-AINVERTEROCPD

(SEENOTE5FORINVERTEROCPDs,ALSOSEEGUIDESECTION9)

FORUNUSEDSERIESSTRINGS

PUT"N/AinBLANKABO

VE

SEEGUIDEAPPENDIXB

FOR

INFORMATIONONMODUL

EAND

ARRAYGROUNDING

___12___MODULES

IN

SERIESSOURCE-CIRC

UIT

___12___MODULES

IN

SERIESSOURCE-CIRC

UIT

___12___MODULESIN

SERIESSOURCE-CIRC

UIT

___12___MODULESIN

SERIESSOURCE-CIRC

UIT

DC

DISCO

INVERTER

A

C

DIS

CO

AC

DC

M

BUILDING

GROUNDING

ELECTRODE

G

Disrega

rdif

providedwith

inverter

COMBINER

MUTILITY

SERVICE

MAINSERVICE

PANEL

MAIN

OCPD

INVERTER

OCPD

J-BOX

1

1

3

4

5

6

7

9

2

3

4

5

8

2

EQUIPMENTSCH

EDULE


26/51


27/51

26

APPENDIXB:STRUCTURAL

STRUCTUREWORKSHEETWKS1

Ifarrayisroofmounted:

Thissectionisforevaluatingroofstructuralmembersthataresitebuilt.Thisincludesrafter

systemsandsitebuilttrusses.Manufacturedtrussandroofjoistsystems,wheninstalledwith

properspacing,meettheroofstructurerequirementscoveredinitem2below.

1. Roofconstruction: Rafters Trusses Other:

___________________________________

2. Describesitebuiltrafterororsitebuilttrusssystem.

a. RafterSize:___x___inches

b. RafterSpacing:________inches

c. Maximumunsupportedspan:_____feet,_____inches

d. Aretheraftersoverspanned?(seetheIRCspantablesinB.2.) Yes No

e. IfYes,completetherestofthissection.

3. Iftheroofsystemhas:

a. overspannedraftersortrusses,

b. thearrayover5lbs/ft2onanyroofconstruction,or

c. theattachmentswithadeadloadexceeding40lbsperattachment;

itis

recommended

that

you

provide

one

of

the

following:

i. Aframingplanthatshowsdetailsforhowyouwillstrengthentherafters

usingthesuppliedspantablesinB.2.

ii. Confirmation certifiedbyadesignprofessionalthattheroofstructurewill

supportthearray.

Ifarrayisgroundmounted:

1. Showarraysupports,framingmembers,andfoundationpostsandfootings.

2. Provideinformationonmountingstructure(s)construction.Ifthemountingstructureis

unfamiliarto

the

local

jurisdiction

and

is

more

than

six

(6)

feet

above

grade,

it

may

requireengineeringcalculationscertifiedbyadesignprofessional.

3. Showdetailonmoduleattachmentmethodtomountingstructure.


28/51

27

B.2 SPANTABLESAframingplanisrequiredonlyifthecombinedweightofthePVarrayexceeds5poundsper

squarefoot(PSForlbs/ft2)ortheexistingraftersareoverspanned.Thefollowingspantables

fromthe2003InternationalResidentialCode(IRC)canbeusedtodetermineiftheraftersare

overspanned.Forinstallationsinjurisdictionsusingdifferentspantables,followthelocal

tables.

SpanTableR802.5.1(1),

Usethistableforrafterspansthathaveconventionallightweightdeadloadsanddonothaveaceilingattached.

10 PSF Dead LoadRoof live load = 20 psf, ceiling not attached to rafters, L/=180

Rafter Size 2 x 4 2 x 6 2 x 8 2 x 10 2 x 12

Spacing(inches)

Species GradeThemeasurementsbelowareinfeetinches

(e.g.910=9feet,10inches).

16Douglas

Firlarch

#2or

better910 144 182 223 259

16 Hemfir#2or

better92 142 1711 2111 255

24Douglas

Firlarch

#2or

better710 119 1410 182 210

24 Hemfir#2or

better73 115 148 1710 209

Usethistableforrafterspansthathaveheavydeadloadsanddonothaveaceilingattached.

20 PSF Dead LoadRoof live load = 20 psf, ceiling not attached to rafters, L/=180


Spacing(inches)



16Douglas

Firlarch

#2or

better86 125 159 193 224

16 Hemfir#2or

better85 123 156 1811 220

24Douglas

Firlarch

#2or

better611 102 1210 158 183

24 Hemfir#2or

better610 100 128 156 1711


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28

SpanTableR802.5.1(2),

Usethistableforrafterspanswithaceilingattachedandconventionallightweightdeadloads.

10 PSF Dead LoadRoof live load = 20 psf, ceiling attached to rafters, L/=240


Spacing(inches)



16Douglas

Firlarch

#2or

better811 141 182 223 259

16 Hemfir#2or

better84 131 173 2111 255

24Douglas

Firlarch

#2or

better710 119 1410 182 210

24 Hemfir#2or

better73 115 148 1710 209

Usethistableforrafterspanswithaceilingattachedandwhereheavydeadloadsexist.

20 PSF Dead LoadRoof live load = 20 psf, ceiling attached to rafters, L/=240


Spacing(inches)



16Douglas

Firlarch

#2or

better86 125 159 193 224

16 Hemfir#2or

better84 123 156 1811 220

24

DouglasFirlarch

#2or

better611

10

2

1210

15

8

183

24 Hemfir#2or

better610 100 128 156 1711

Usetheconventionallightweightdeadloadtablewhentheexistingroofingmaterialsarewood

shake,woodshingle,compositionroofingorlightweighttileroofs.(Therationaleforallowing

thesetablestobeusedisthattheinstallationofaPVsystemshouldbeconsideredaspartof

theliveload,sinceadditionalloadingwillnotbeaddedtothesectionoftheroofwhereaPV

arrayisinstalled.)

Whereheavy

roofing

systems

exist

(e.g.

clay

tile

or

heavy

concrete

tile

roofs),

use

the

20

lbs/ft

2

deadloadtables.


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29

APPENDIXC:SPECIALELECTRICALTOPICS

ModuleFrameGrounding:

Theprimary

concern

raised

by

industry

experts,

including

the

Solar

ABCs,

has

been

the

fact

that

theanodizedaluminumframesincontactwithanodizedaluminumrailsmaynotcreatean

adequateandreliableelectricalconnection.Untilthisissuewasraised,mostinspectorsand

contractorsweresatisfiedwithgroundingthemetalsupportstructureratherthangrounding

individualmodules.Severalstandardandnewgroundingmethodscanaddresstheelectrical

bondofthemoduleframetoitssupportbypenetratingeachnonconductivesurfacewitha

sharp,metallurgicallycompatibledevice.Thisdevicemaybeasimpleasastainlesssteelstar

washer,orasuniqueasaspeciallydesignedgroundingclipwithsharppointstopiercethe

anodizing.

PVmodule

grounding

options

include

avariety

of

methods

including

grounding

screws

or

lugs

oneachmoduleconnectedtoagroundwire,ormethodsthatcreateanelectricalbond

betweenthemoduleframeanditssupportstructure.InstallationmanualsforPVmoduleshave

becomemoreexplicitaboutgroundingmethods,butitisnotnecessaryforthemanualtostate

everypossiblemethodofcompliance.TheUL1703teststandardforthesafetyofPVmodulesis

beingrevisedtoallowanymethodthatmeetstherequirementsofUL467,Groundingand

BondingEquipmentaslongasthemetalsarecompatibleandthematerialsareableto

withstandanoutdoorenvironmentandexpandstheoptionsforgroundingmodules.


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30

ACConnectiontoBuildingElectricalSystems

ACConnectiontoLoadSideofMainServicePanel

The

connection

of

PV

systems

inverter

output

circuit

to

the

load

side

of

the

Main

Service

panel

isthemostcommoninstallationmethod.Thistypeofconnectionisgovernedbythe

requirementsofNEC690.64(B). TheserequirementsdictatethatthemaximumsumofOCPDs

thatcanbefedintoaconductororbusbaris120%ofthebusbarorconductorrating(NEC

690.64(B)(1)).Forexample,ifabusbarhasacurrentratingof225amps,andamainbreaker

ratedat200amps,thenthemaximumbreakerratingforaPVinverteris70ampsasshown

below:

MaximumallowableOCPD:Busbar=225A;120%ofBusbar=225Ax1.2=270A

ExistingMainOCPD=200A

MaximumPVOCPD=MaximumallowableOCPDExistingMainOCPD

=270A200A=70A

Todeterminethemaximumsizeinverterthatcanbefedintoa70AOCPD,rememberthatmost

circuitbreakersandotherOCPDsarelimitedto80%oftheircurrentratingforcontinuous

operation. Thismeansthat70Acircuitbreakermustbesizedsothat56Acanpassthroughthe

breakeronacontinuousbasis(3hoursormore).SincePVinvertersareratedbasedontheir

maximumpowerat40Cforacontinuous3hourperiod,aninvertercapableofacontinuous

56Aiscapableof11,648Wattsat208Vac;13,440Wacat240Vac;and15,512Wacat277Vac.

Theonlywaytoputmorecurrentintotheloadsideoftheservicepanelinthisisexample,isto

reducethesizeofthemainOCPD.TotheextentthatthemainOCPDisreduced,thePVinverter

OCPDmaybeincreased.However,anytimeamainOCPDisreduced,aloadcalculation

followingtherequirementsofNECArticle220mustbecalculatedtoshowthattheloadonthe

mainOCPDwillnotseemorethanan80%continuousloadatthechosenOCPDrating.

Ifnootherpanelboardsexistonthisservice,theonlyotheropportunitytoinstallalargerPV

systemistomakeasupplysideserviceconnection(NEC690.64(A)).Thismethodisdiscussedin

theACSupplySideConnectionsectioninthisAppendix.


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31

ACConnectiontoSubpanel:

Whenasiteservicecontainsmorethanonepanelboard,thepanelsfedfromthemainservice

panelarereferredtoassubpanels.TheNEC,in690.64(B)(1),allowstheinverterOCPDtobe

connectedatanylocationinthepremiseswiringsystem,providedthatthe120%ofbusbarand

conductorampacity

limitation

is

observed.

Forexample,alargeresidencehasamainpanelwitha400ampratingwitha400ampmain

OCPD.Froma200ampbreakerinthis400amppanelisa200amppanelattheoppositeend

oftheresidence.Inthisexample,thePVarrayislocatedmuchclosertothe200amppanel,so

thepreferredinterconnectionpointisthe200amppanel.AslongastheinverterOCPD

complieswithlimitationsofthe200amppanel,theinvertercaninterconnectatthatpanel.

Witha200ampbusbaranda200ampmainbreaker,thelargestPVOCPDallowedinthatpanel

is40amps(seediscussiononACConnectiontoLoadSideofMainServicePanelinthis

Appendix).Assuming

a40

amp

PV

OCPC

is

sufficient

for

the

PV

inverter

(e.g.

7000

Watt

inverter),theissuesofconcerninthesubpanelareaddress.

Nowconsiderthecurrentflowatthemainservicepanel.The2008NECinstructstheinstallerto

calculatethesumofthesupplyOCPDsatthemainservicepanelbasedontheratingofinverter

OCPD,whichis40amps,notthe200ampfeederbreakerthatfeedsthesubpanel[NEC

690.64(B)(1)].Clearly,the40ampPVOCPDdoesnotexceedthe120%ofbusbarratinginthe

400amppanel,whereas,hadthe200ampfeederbreakervaluebeenusedinthecalculation,

theinstallationwouldhavebeeninviolation.

Takingthisexampleoneadditionalstep,shouldanotherPVinverterbedesired,duetothelarge

electricalconsumptionoftheresidence,thereisstillampacityallowanceinthe400ampmainpanelbusbar.TheallowableinverterOCPDsizewouldbecalculatedasfollows:

MaximumallowableOCPD:Busbar=400A;120%ofBusbar=400Ax1.2=480A

ExistingMainOCPD=400A;InverterOCPDin200Asubpanel=40A

MaximumPVOCPDin400Apanel=MaximumallowableOCPDExistingMainOCPD

InverterOCPDin200Asubpanel=480A400A=40A

Thereforean

additional

40A

inverter

OCPD

could

be

placed

in

the

main

panel

without

any

changestothepanel.

ShouldalargerPVsystembedesiredthancouldbehandledbythetwo40Abreakersinthis

example,refertothediscussionsinACConnectiontoLoadSideofMainServicePanelinthis

Appendix.


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32

ACSupplySideConnection:

WhenthesizeofPVsystemisrelativelylargerelativetothesizeofthesiteservice,itisfairly

commontoconsiderasupplysideconnectionfortheinverterOCPD.Wheneverthe120%

allowanceforOCPDsconnectedtobusbarsorconductorscannotbeobserved,duetosizeof

therequired

PV

OCPD

and

the

limited

size

of

the

service

panel,

the

supply

side

connection

may

betheonlyalternativeavailable.Asupplysideconnectionbydefinitionismadebetweenthe

servicemeterandtheservicedisconnect.

Notallservicescanbelegallyconnectedatthispoint.Forinstance,manyallinonemeter

panels,usedroutinelyinnewresidentialconstruction,havenomeansofmakingsucha

connectionwithoutviolatingthelistingoftheproduct.Ontheotherendofthesizespectrum,

manylarge3,000ampservicepanelshavenospaceforsuchaconnection.Tofurther

complicatethissituation,someutilitieshavebegunrequiringmeteringcurrenttransformersto

beinstalledontheloadsideofserviceOCPD,makingasupplysideconnectionimpossible.

Withthosecomplicationsaside,wewilldiscussthesituationswhereasupplysideconnectionis

possibleanddoesnotviolatetheequipmentlistingsoftheserviceequipment.TheNECcovers

supplysideconnectionsin230.82.ThesupplysideconnectionforthePVsystemmusthavea

disconnectandOCPDlocatedimmediatelyadjacenttothemainservicedisconnectasspecified

in230.91.Eventhoughthetaprule,discussedinArticle240.99doesnotapplytosupplyside

connections,thesizeoftheconductorsconnectingthesupplysideconnectiontothePVOCPD

aresizedaccordingtoratingoftheOCPD.Therefore,ifa60ampfuseddisconnectisusedas

thePVOCPD,theconductorsizebetweenthesupplysideconnectionandthePVOCPDneed

onlybe6AWG,regardlessofthesizeofserviceconductors.

ThemethodofterminationofPVconductorstothesupplyconductorsorbusbar,dependsontheserviceequipmentandconductors.Inanycase,theservicevoltagewillneedtobe

interruptedtotieintotheserviceconductorsorbusbarunlesstheveryrareexceptions

outlinedinNFPA70Eareinvolvedatfacilitieslikehospitalswherethecutinprocessmustbe

donewhileenergized.Typicalterminationmethodsincludeseveraloptions:

1. luggingtoanaccessibleperforatedbuswithinserviceequipment;

2. usingemptysetofdoublebarrellugswithinserviceequipment;

3. usingpiercinglugsonconductorsbetweenmeterandservicedisconnect;

4. anylugidentifiedformakingconnectionstoconductorsofthesizerangeinstalled.

Ofteninstallinglugsonserviceconductorswillrequireremovalofserviceconductorsand

conduitandreinstallingconductorswithajunctionboxtoaccommodatetheconnection.


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33

SourceCircuitOvercurrentProtection:

SourcecircuitovercurrentprotectionmustbesizedsothatboththePVmoduleandthe

conductorfromthemoduletotheovercurrentdeviceareproperlyprotected[690.9(A),240.20

(A)].PVmodulesmustbeprotectedsothatthemaximumseriesfuserating,printedonthe

listinglabel,

is

not

exceeded.

It

is

important

to

note

that

even

though

the

listing

label

states

fuserating,amoreaccuratetermwouldbethemaximumseriesovercurrentprotection

ratingsinceeitherafuseoracircuitbreakermaybeusedtosatisfythislistingrequirement.The

modulemaybeprotectedeitherbyinstallingfusesorcircuitbreakersinaseriesstringof

modulesorbythedesignofthePVsystem.

InverterslistedwithaMaximumutilitybackfeedcurrentthatiswellabove2amps(typically

equaltothemaximumallowableoutputovercurrentprotection)mustbeassumedtoprovide

backfeedcurrenttothePVarray.Eachsourcecircuitmusthaveovercurrentprotectionthatis

greaterthanorequaltotheminimumPVSourceCircuitcurrentratingandlessthanorequalto

the

maximum

series

fuse

rating.

Explanation:Foranarraywithamaximumsourcecircuitcurrentof6.8ampsandamaximum

seriesfuseratingof15amps,Theminimumfuseratingwouldbe9amps(nextlargerfuseratingabove

8.5amps;6.8Ax1.25=8.5A)andthemaximumwouldbe15amps.

Inverterslistedwithamaximumutilitybackfeedcurrentthatis2ampsorless(e.g.FroniusIG

5100),twosourcecircuitscanbeconnectedtotheinverterwithoutrequiringovercurrent

protectiononeithercircuit.

Explanation:Ifanarraycontainingtwostringsinparallelisconnectedtoaninverterthatisa

limitedbackfeedingsource(2ampsorless),themaximumcurrentinastringisequaltothecurrentfrom

theotherstringinparallelplusthemaximumbackfedcurrentfromtheinverter.Ifthemaximumcurrent

ofeachstringis6.8Amps,andtheinverterprovides2amps,thenthemaximumcurrentinafaultatanyPVmoduleis8.8Ampsandthemaximumseriesfuseratingofthemodulewillneverbeexceeded(i.e.a

modulewithanISCof5.4ampwillhaveamaximumseriesovercurrentdeviceratingofatleast10amps).

Forsmallerinverterslistedwithamaximumutilitybackfeedcurrentthatisnolargerthanthe

modulemaximumovercurrentdevicerating(e.g.EnphaseM200witha1.6amputility

backfeed),asinglesourcecircuitcanbeconnectedtotheinverterwithoutrequiring

overcurrentprotectiononthearraycircuit.

Explanation:Ifasinglestringarray(couldbeasinglemodulearray)isconnectedtoaninverter

thatprovideslessthantheratedmodulemaximumovercurrentdeviceratinginbackfeedcurrent,itis

equivalenttohavingthatsizeovercurrentdevicepreventcurrentflowfromtheutilityandthearrayis

protected.ThemaximumreversefaultcurrentatanyPVmoduleistheamountoftheinverterutilitybackfeedcurrentandthemaximumseriesfuseratingofthemodulewillneverbeexceeded.


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34

DisconnectingMeans:

TheNECdefinesdisconnectingmeansinthefollowway:

NECArticle100DisconnectingMeans.Adevice,orgroupofdevices,orothermeansbywhich

theconductors

of

acircuit

can

be

disconnected

from

their

source

of

supply.

Aprimarypurposeofadisconnectingmeansistoopenacircuitprovidingasourceofsupplyso

thattheequipmentfedbythatsourcecanbemaintainedwithoutexposingtheoperatorto

hazardousvoltages(NFPA70E).

DisconnectingMeansinInverters:

Variousinvertershaveprovidedavarietyofintegraldcandacdisconnects.Thesedisconnects

mayormaynotprovidethenecessaryisolationformaintenance.Thekeyindifferentiating

whetherthesupplieddisconnectsprovidetheappropriateisolationistoreviewtheprimary

method

of

maintenance

and

repair

of

the

device.

If

the

device

has

a

standard

means

of

removingthepartsneedingservice,withoutexposingthetechniciantohazardousvoltages

(anythingover50Volts),thesupplieddisconnectsmeettheintentofmaintenance

disconnectingmeans.Ifthetechnicianisexposedtovoltagesabove50Voltsduringservice,

evenwiththesupplieddisconnectingmeans,externaldisconnectingmeansmaybenecessary.

ItisimportanttopointoutthateverycurrentlyavailablePVinverter,thatdoesnotoperateon

abatterysystem,hasinputcapacitors.Thesecapacitorsmayremainenergizedforfiveormore

minutesafterallexternalsourcesareremovedfromaninverter.Internalbleedresistors

removethisvoltageoveraprescribedtimeperiod,andwarninglabelsareprovidedonthe

invertertoidentifythishazard.Thishazardistypicalofelectricalequipmentusingsignificant

capacitance.This

capacitive

source

is

controlled

by

warning

signage

and

bleed

resistors

and

not

generallybyinternalorexternaldisconnects.Disconnectsshouldnotberequiredtocontrolthe

capacitivesourceduringmaintenanceorserviceoftheinverter.

UtilityRequiredDisconnectingMeans:

UtilitiesmayrequiresomemethodtoisolatePVsystemsfromtheirgridduringmaintenance

procedures.Theisolationdeviceisusuallyrequiredtoprovideavisiblebreakinorderto

comply,andmoldedcasecircuitbreakersdonotmeetthatrequirement.Severalutilities,

includingtheutilitywiththemostPVinstallationsintheU.S.,PacificGas&Electric,have

adoptedapolicy

of

allowing

residential

PV

systems

with

self

contained

meters

(the

most

commonresidentialtypemeter)toprovidethenecessaryvisiblebreakviaremovalofthe

meter.Forinstallationswithcurrenttransformermeters,aseparatevisiblebreakswitchis

almostalwaysrequired.Whentheutilityrequiresavisiblebreakswitch,thisswitchmaybe

usedtoprovidetheNECrequiredacswitchformaintainingtheinverteriftheinverterislocated

intheimmediatevicinityoftheswitch.


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35

Provisionsforthephotovoltaicpowersourcedisconnectingmeans:

The2005NECstatesin690.14(C)(1),Location.Thephotovoltaicdisconnectingmeansshallbe

installedatareadilyaccessiblelocationeitheroutsideofabuildingorstructureorinside

nearestthepointofentranceofthesystemconductors.Thephotovoltaicsystemdisconnecting

meansshall

not

be

installed

in

bathrooms.

a) ReadilyaccessibleNECArticle100states,Accessible,Readily(ReadilyAccessible).

Capableofbeingreachedquicklyforoperation,renewal,orinspectionswithoutrequiring

thosetowhomreadyaccessisrequisitetoclimboverorremoveobstaclesortoresortto

portableladders,andsoforth.

b) Readilyaccessibleprovisionisprimarilyforemergencyoperation.Ifthedisconnectis

notmountedincloseproximityoftheserviceentrancedisconnect(usuallywithin10

feetofthemeterlocationorservicedisconnectswitch),thenadiagramordirectory

mustbeprovidedtoclearlyidentifywherethedisconnectingmeansislocated.

c) A

rooftop

disconnect

on

a

residential

roof

will

normally

not

qualify

as

a

readily

accessibledisconnect.

Anexceptiontothisrequirementwasaddedtothe2005NECtoprovideadditionalclarification

forresidentialandbuildingintegratedPVsystems.Thisexceptionreads:

Exception:Installationsthatcomplywith690.31(E)shallbepermittedtohavethe

disconnectingmeanslocatedremotefromthepointofentryofthesystemconductors.

NEC690.31(E)states:

(E)Direct

Current

Photovoltaic

Source

and

Output

Circuits

Inside

aBuilding.

Where

direct

currentphotovoltaicsourceoroutputcircuitsofautilityinteractiveinverterfromabuilding

integratedorotherphotovoltaicsystemareruninsideabuildingorstructure,theyshallbe

containedinmetallicracewaysorenclosuresfromthepointofpenetrationofthesurfaceofthe

buildingorstructuretothefirstreadilyaccessibledisconnectingmeans.Thedisconnecting

meansshallcomplywith690.14(A)through690.14(D).

Althoughmetalcladcableisnotspecificallycalledoutin690.31(E),manyjurisdictionsconsider

installationswithmetalcladcableasmeetingtheintentofthisnewprovision.Notethatthis

newsectionspecificallymentionsbuildingintegratedsystems.Thewaythe2002NECwas

written,aroof

integrated

PV

system

cannot

reasonably

comply

the

690.14(C)(1)

as

written.


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36

APPENDIXD:COSTSOFPERMITS

Eachjurisdictionmayhavedifferentinternalcostsstructuresandapproachestoworking

withsolarPVsystems.Thefollowingsectionisprovidedasasuggestionindevelopingthe

coststructureforalocaljurisdiction.

Explanation:Costsforpermitsareoftenbasedontheoverallprojectcost.Thisworkswellfor

manyconventionalprojectsbecausethisaccuratelyrepresentsthescaleoftheproject.However,

withaPVinstallation,theequipmentcostsaremuchhigherthanwithotherprojectsofsimilar

scope.ItisthereforerecommendedthatanalternativepermitfeescalebeusedforPVsystem

installations.ThescopeofaPVinstallationissimilartothatofinstallingaretrofittedresidential

HVACsystem.ThepermittingcostsforaPVsystemshouldbesimilartothoseforanHVAC

system.

Althoughinitialplanreviewandfieldinspectioncostsmaybeslightlyhigherforthefirstfew

systems,thosecostsshouldreduceasthelocaljurisdictionbecomesfamiliarwiththe

installations.Asubdivisionofmorethan10unitsshouldbeconsideredforanadditionalfee

reductionbasedontherepetitivenatureofthereviews.Asuggestedfeescheduleisasfollows:

SmallPVsystem(upto4kW):$75 $200

LargePVsystem(upto10kW):$150 $400

Forsystemsof1050kW,considerapermitcostof$15 $40perkW.

Forsystemsof50100kW,considerapermitcostof$1,500.

Forsystemsof100500kW,considerapermitcostof$3,000.

Forsystemsupto1000kW,considerapermitcostof$3,000$5,000.


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37

APPENDIXE:TEMPERATURETABLES


39/51

High2%

DB 0"0.5" 0.5"3.5" 3.5"12" 12"36" Max Min

AK BARROW 4 14 47 36 31 28 19 43

AK DEADHORSE 23 19 52 41 36 33 24 45

AK BARTERISWSOAP 11 15 48 37 32 29 N/A N/A

AK KOTZEBUE 5 20 53 42 37 34 24 39

AK BETTLES 205 26 59 48 43 40 29 47

AK FORTYUKON 135 27 60 49 44 41 29 48

AK NOME 7 21 54 43 38 35 24 37

AK SAINTMARY`S(AWOS) 95 22 55 44 39 36 24 34

AK UNALAKLEETFIELD 4 21 54 43 38 35 N/A N/A

AK BETHEL 46 22 55 44 39 36 25 35

AK MCGRATH 103 25 58 47 42 39 2846

AK TALKEETNA 105 24 57 46 41 38 27 36

AK KENAIMUNICIPALAP 26 20 53 42 37 34 24 33

AK SOLDOTNA 33 21 54 43 38 35 24 34

AK NENANAMUNICIPALAP 109 27 60 49 44 41 30 46

AK FAIRBANKS 138 27 60 49 44 41 31 43

AK EIELSONAFB 167 27 60 49 44 41 31 44

AK BIGDELTA 388 25 58 47 42 39 28 47

AK FTRICHARDSON/BRYANTAPT 115 23 56 45 40 37 27 31

AK GULKANA 481 24 57 46 41 38 27 45

AK ELMENDORFAFB 65 23 56 45 40 37 25 29

AK ANCHORAGE 35 22 55 44 39 36 25 26

AK ANCHORAGEMERRILLFIELD 42 23 56 45 40 37 26 26

AK VALDEZWSO 7 21 54 43 38 35 25 17

AK WHITTIER 9 21 54 43 38 35 23 17

AK SEWARD 18 21 54 43 38 35 26 17

AK NORTHWAYAIRPORT 522 26 59 48 43 40 28 48

AK CORDOVA 12 21 54 43 38 35 26 23

AK STPAULIS. 7 12 45 34 29 26 15 19

AK COLDBAY 29 15 48 37 32 29 19 17

AK DILLINGHAM(AMOS) 29 21 54 43 38 35 24 34

AK KINGSALMON 15 22 55 44 39 36 25 35

AK PORTHEIDEN(AMOS) 29 18 51 40 35 32 N/A N/A

AK ILIAMNAARPT 56 21 54 43 38 35 N/A N/A

AK HOMERARPT 27 18 51 40 35 32 21 21

AK MIDDLETONISLANDAUT 36 17 50 39 34 31 19 10

AK KODIAK 34 20 53 42 37 34 24 17

AK YAKUTAT 9 20 53 42 37 34 2421

AK SITKAJAPONSKIAP 4 19 52 41 36 33 24 11

AK JUNEAUINT`LARPT 3 23 56 45 40 37 27 18

AK WRANGELL 13 21 54 43 38 35 25 13

AK KETCHIKANINTLAP 23 22 55 44 39 36 25 14

AK ANNETTE 34 23 56 45 40 37 27 12

AK SHEMYA 30 13 46 35 30 27 14 8

AK ADAKNAS 5 15 48 37 32 29 20 11

AK FIVEFINGERISLAND 7 18 51 40 35 32 22 9

AL MOBILE 67 34 67 56 51 48 36 7

AL MONTGOMERY 62 36 69 58 53 50 37 9

DesignTemperaturesForVariousU.S.CitiesThefollowingtableindicatesthe2%designtemperature(averagedforJuneAugust)forvariouscities;andthe

lowestexpectambienttemperature[690.7]foreachlocation(MinMeanExtremeAnnualDB).Thefirstcolumnis

elevationofthestationforcomparingclimateswithlocationsnotlisted.ColumntworepresentstheASHRAE2%

designtemperature(1).Thethirdthroughsixthcolumnistheresultantambienttemperatureinsidetheconduit

unloaded(2).Itisthetemperaturethewireissubjectedto.Thelastcolumnisthelowestexpectambient

temperatureforthatcity,basedon30yearsofweatherdata.Thisisthetemperaturetobeusedformaximum

voltagecalculationsinNEC690.7.AlltemperaturesinCelcius.

Distanceaboveroof.Temp.

in

Conduit

in

Sunlight

(C)Elev

(M)

ExtremeAnnual

DB

MeanState Station


40/51

State Station Elev (M) 2% 0"-0.5" 0.5"-3.5" .3.5"-12" 12"-36" Max Min .

AL MAXWELLAFB 53 36 69 58 53 50 38 6

AL DOTHANMUNICIPALAP 97 35 68 57 52 49 37 8

AL CAIRNSFIELDFORTRUCKER 91 35 68 57 52 49 37 8

AL BIRMINGHAM 192 35 68 57 52 49 37 12

AL GADSENMUNI(AWOS) 173 34 67 56 51 48 N/A N/A

AL TUSCALOOSAMUNICIPALAP 51 36 69 58 53 50 37 12

AL ANNISTONMETROPOLITANAP 186 35 68 57 52 49 37 12

AL CENTREVILLEWSMO 140 34 67 56 51 48 36 11

AL HUNTSVILLE 190 35 68 57 52 49 36 13

AL MUSCLESHOALSREGIONALAP 164 35 68 57 52 49 37 13

AL DAUPHINISLAND 8 31 64 53 48 45 33

2

AR NORTHLITTLEROCK 170 35 68 57 52 49 37 12

AR LITTLEROCKADAMSFIELD 78 37 70 59 54 51 39 12

AR LITTLEROCKAFB 103 37 70 59 54 51 39 13

AR WALNUTRIDGE(AWOS) 83 35 68 57 52 49 38 13

AR JONESBOROMUNICIPAL 80 36 69 58 53 50 38 16

AR BLYTHEVILLEAFB 79 36 69 58 53 50 38 15

AR STUTTGART(AWOS) 68 36 69 58 53 50 38 9

AR PINEBLUFFFAAAP 63 36 69 58 53 50 38 9

AR TEXARKANAWEBBFIELD 110 37 70 59 54 51 39 10

AR ELDORADOGOODWINFIELD 76 37 70 59 54 51 39 9

AR FORTSMITH 141 37 70 59 54 51 39 14

AR BENTONVILLE(AWOS) 395 34 67 56 51 48 36 17

AR FAYETTEVILLE

DRAKE

FIELD 381 35 68 57 52 49 37

18AR HARRISONFAAAP 418 35 68 57 52 49 37 16

AR FLIPPIN(AWOS) 350 36 69 58 53 50 N/A N/A

AR BATESVILLE(AWOS) 141 37 70 59 54 51 38 13

AR ROGERS(AWOS) 415 34 67 56 51 48 37 16

AZ DOUGLASBISBEEDOUGLASIN 1249 37 70 59 54 51 40 9

AZ TUCSON 779 41 74 63 58 55 43 3

AZ DAVISMONTHANAFB 808 40 73 62 57 54 43 2

AZ SAFFORD(AMOS) 950 40 73 62 57 54 42 10

AZ PHOENIX 339 43 76 65 60 57 46 0

AZ LUKEAFB 331 44 77 66 61 58 47 1

AZ YUMAINTLARPT 62 44 77 66 61 58 47 2

AZ KINGMAN(AMOS) 1033 38 71 60 55 52 40 8

AZ PAGEMUNI(AMOS) 1304 37 70 59 54 51 40 9

AZ PRESCOTTLOVE

FIELD 1536 35 68 57 52 49 37

13

AZ WINSLOWMUNICIPALAP 1490 36 69 58 53 50 39 15

AZ FLAGSTAFF 2135 30 63 52 47 44 32 22

CA ELTOROMCAS 116 33 66 55 50 47 38 3

CA TUSTINMCAF 18 34 67 56 51 48 39 2

CA MARCHAFB 462 38 71 60 55 52 42 2

CA ONTARIO 303 38 71 60 55 52 42 1

CA NORTONAFB/SANBERN 353 39 72 61 56 53 43 2

CA BURBANKGLENDALEPASADENA 225 37 70 59 54 51 41 1

CA SANLUISOBISPO 64 31 64 53 48 45 37 2

CA SANDIEGO 9 29 62 51 46 43 34 5

CA SANDIEGONORTHISLANDNA 14 28 61 50 45 42 34 5

CA CAMPPENDLETONMCAS 22 34 67 56 51 48 39 3

CA SANDIEGOMIRAMARNAS 139 33 66 55 50 47 38 1

CA LOSANGELES 32 29 62 51 46 43 35 4

CA LONGBEACH 17 33 66 55 50 47 39 2

CA EDWARDSAFB 705 41 74 63 58 55 44 10

CA DAGGETT 588 42 75 64 59 56 45 5

CA LANCASTERGENWMFOXFIEL 712 39 72 61 56 53 42 9

CA GEORGEAFB 869 38 71 60 55 52 41 6

CA SANDBERG 1376 33 66 55 50 47 35 6

CA BAKERSFIELD 150 40 73 62 57 54 43 2

CA FRESNO 100 40 73 62 57 54 42 3

CA VISALIAMUNI(AWOS) 89 38 71 60 55 52 40 3

2


41/51

State Station Elev (M) 2% 0"-0.5" 0.5"-3.5" .3.5"-12" 12"-36" Max Min .

CA PT.PIEDRASBLANCA 21 26 59 48 43 40 N/A N/A

CA POINTMUGUNF 3 28 61 50 45 42 34 2

CA SANTABARBARAMUNICIPALA 2 29 62 51 46 43 35 1

CA SANTAMARIA 72 29 62 51 46 43 35 3

CA PASOROBLESMUNICIPALARP 243 39 72 61 56 53 43 6

CA BISHOPAIRPORT 1250 38 71 60 55 52 41 14

CA CASTLEAFB 60 38 71 60 55 52 40 3

CA SACRAMENTO 8 38 71 60 55 52 41 3

CA MATHERFIELD 29 38 71 60 55 52 41 3

CA MCCLELLANAFB 25 39 72 61 56 53 42 3

CA BEALEAFB 38 38 71 60 55 52 41

3

CA SACRAMENTOMETROPOLITANA 7 38 71 60 55 52 41 3

CA SALINASMUNICIPALAP 21 28 61 50 45 42 35 1

CA STOCKTONMETROPOLITANARP 6 38 71 60 55 52 41 3

CA OAKLANDMETROPOLITANARPT 1 28 61 50 45 42 33 1

CA SANFRANCISCO 5 28 61 50 45 42 35 1

CA SANJOSEINTLAP 15 34 67 56 51 48 38 0

CA BLUECANYONAP 1609 29 62 51 46 43 31 9

CA UKIAHMUNICIPALAP 188 38 71 60 55 52 42 3

CA REDBLUFFMUNICIPALARPT 106 41 74 63 58 55 44 4

CA REDDINGMUNICIPALARPT 153 41 74 63 58 55 44 5

CA EUREKA 18 20 53 42 37 34 N/A N/A

CA ARCATA 69 21 54 43 38 35 28 3

CA MOUNT

SHASTA 1077 33 66 55 50 47 35

12CA ALAMEDANAS 4 29 62 51 46 43 34 3

CA MOUNTAINVIEWMOFFETTFLD 11 31 64 53 48 45 36 0

CA TRAVISFIELDAFB 18 37 70 59 54 51 41 3

CA LEMOOREREEVESNAS 73 40 73 62 57 54 42 3

CA IMPERIAL 17 44 77 66 61 58 47 1

CA PALMSPRINGSTHERMALAP 34 44 77 66 61 58 48 5

CA BLYTHERIVERSIDECOARPT 118 45 78 67 62 59 48 1

CA POINTARENA 12 17 50 39 34 31 21

Date post:	03-Apr-2018
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