1、 An Americ An nA tion Al St And Ard NECA 412-2012 Standard for Installing and Maintaining Photovoltaic (PV) Power Systems Published by National Electrical Contractors AssociationT #% $% #ional $;andard u!iem $afe; Genera Safe Wor? Practices ectrica !azards attery Systems ns;alling $olar “ho;ovol;ai+
2、 “oer $s;ems Genera Potovotaic rrays %a*le of on;en;s iv Inverters and er $s;ems nne? #eferen+e $;andardsN #% $% #s and ppli+a;ions n+lded Tis standard covers te instaation of ow votage and potovotaic power systems rated V and ess for grid connected and stand aone operation for residentia commercia
3、and industria appications See igure for an exampe of potovotaic modues forming an array tat is part of a potovotaic power system “rod+;s and ppli+a;ions ?+lded Tis standard does not appy to soar eating systems or potovotaic power systems rated more tan V #egla;or and !;her #eqiremen;s a information
4、in tis pubication is intended to conform to te Nationa ectrica ode NSI NP Standard Instaers sa compy wit te N appicabe state and oca codes and manufacturers instructions wen instaing soar potovotaic power systems b Ony quaified persons as defined in te N famiiar wit te construction and instaation of
5、 soar potovotaic power systems soud perform te tecnica wor? described in tis pubication dministrative functions suc as receiving anding and storing required in Section and oter tas?s can be performed under te supervision of a quaified person wor? soud be performed in accordance wit NP erna;ingrren;
6、a+ odle l;erna;ing rren; “ho;ovol;ai+ odle compete environmentay protected unit consisting of soar ces optics inverter and oter components excusive of trac?er designed to generate ac power wen exposed to sunigt rra mecanicay integrated assemby of modues or panes wit a support structure and foundatio
7、n trac?er and oter components as required instaed as a system to form a directcurrent power producing unit See igure for an exampe of a potovotaic array ;hori; aving risdi+;ion n organization office or individua responsibe for enforcing te requirements of a code or standard or for approving equipmen
8、t materias an instaation or a procedure zim;h Te orientation ange of te soar array wit respect to soar sout expressed in degrees Sun position to te east of soar sout is typicay represented by a positive azimut ange were sun position to te west of soar sout is typicay represented by a negative azimut
9、 ange a;er n eectrocemica device tat transforms stored cemica energy into eectric energy during discarge a;er harger device tat can maintain a unidirectiona current in a battery in te opposite direction to tat during discarge tereby converting efini;ions igure ypical roof9ounted photovoltaic array $
10、hoto irol;e Liquid soution of diute sufuric acid in wic battery eements are immersed for te ifetime of te ce qipmen; ronding ond+;or Te conductive pats instaed to connect normay non current carrying meta parts of equipment togeter and to te system grounded conductor or to te grounding eectrode condu
11、ctor or bot rid+onne+;ed Generation tat operates in parae wit te eectric utiity grid rond Te eart ronded ronding onnected connecting to ground or to a conductive body tat extends te ground connection *rid $s;em system comprised of mutipe power sources Tese power sources may incude potovotaic wind mi
12、cro ydro generators enginedriven generators and oters but do not incude eectrica production and distribution networ? systems nergy storage systems suc as batteries do #% $% # angle Orientation ange of te sun wit respect to te orizon expressed in degrees nsola;ion Te average soar energy tat reaces te
13、 earts surface at a given ocation per day expressed as ?iowatt ours per square meter per day ?W m day n;era+;ive $s;em soar potovotaic system tat operates in parae wit and may deiver power to an eectrica production and distribution networ? or te purpose of tis definition an energy storage subsystem
14、of a soar potovotaic system suc as a battery is not anoter eectrica production source nver;er quipment tat is used to cange votage eve or waveform or bot of eectrica energy ommony an inverter aso ?nown as a power conditioning unit PU or power conversion system PS is a device tat canges dc input to a
15、n ac output Inverters may aso function as battery cargers tat use aternating current from anoter source and convert it into direct current for carging batteries See igure for an exampe of a sma inverter instaed for a PV system nver;er np; ir+i; onductors between te inverter and te battery in stand a
16、one systems or te conductors between te inverter and te potovotaic output circuits for eectrica production and distribution networ? nver;er !;p; ir+i; onductors between te inverter and an ac paneboard for stand aone systems or te conductors between te inverter and te service equipment or anoter eect
17、ric power production source suc as a utiity for eectrica production and distribution networ? nver;er +on;rols ontros tat reguate power conversion from to syncronize to te eectric utiity grid monitor bus votage and frequency and provide protection in te event of a faut faiure or abnorma operating con
18、dition odle compete environmentay protected unit consisting of soar ces optics and oter components excusive of trac?er designed to generate dc power wen exposed to sunigt onopole $*arra PV subarray tat as two conductors in te output circuit one positive and one negative Two monopoe PV subarrays are
19、used to form a bipoar PV array Ne;me;ering Utiity biing practice tat permits power deivery from distributed generation sources to te eectric utiity grid across te utiity revenue meter N #% $% #iner $oer *er Power consumed by induction macusted for environmenta conditions at te instaed ocation $olar
20、+ell Te basic potovotaic device tat generates eectricity wen exposed to igt $olar rradia;ion Te tota amount of soar energy accumuated on an area over time typicay expressed as ?iowatt ours per square meter ?W m Soar irradiation is te principe measurement used to quantify soar energy production over
21、time so see Insoation and Pea? Sun !ours $olar modle Severa soar ces tat are eectricay and mecanicay interconnected and encapsuated $olar “ho;ovol;ai+ $s;em Te tota components and subsystems tat in combination convert soar energy into eectric energy suitabe for connection to a utiization oad $;andlo
22、ne $s;em soar potovotaic system tat suppies power independenty of an eectrica production and distribution networ? See igure next page as an exampe of a stand aone system $*arra n eectrica subset of a PV array #% $% #ion Process of matcing te operating votage frequency and pase ange of one source to
23、anoter source prior to paraeing te sources togeter %il; angle Te orientation ange of te soar array wit respect to te orizon expressed in degrees &;ili;in;era+;ive inver;er n inverter intended for use in parae operation wit an eectric utiity to suppy common oads tat may deiver power to te utiity N #%
24、 $% #rod+;ion igure a?ic co9ponent? of a photovoltaic ?y?te9 +illu?tration i? intended a? a concept only igure ypical photovoltaic ?y?te9 with battery ?torage dc ?y?te9 output +“ote hi? i? a ?i9plified diagra9 concept and i? not intended to ?how all wiring grounding bonding overcurrent protection an
25、d ?o forthtransfer from ter $s;em !pera;ion Power output from a soar potovotaic array is greatest on a brigt sunny day wit ow ambient temperature Soar power output drops off wit sunigt intensity suc as during coudy days wen te soar panes are saded in some way at sun up dus? or oter times wen te soar
26、 panes are not pointed directy at te sun Soar power production aso drops off as te soar panes eat up suc as on a very ot summer day Severa factors affect soar power production incuding atmosperic conditions ambient temperature and ground snow cover tmosperic conditions suc as coudy overcast s?ies ig
27、 umidity or poution in te air and te tic?ness of te atmospere due to eevation can negativey affect soar power production Soar power production is most efficient in ower ambient temperatures as cooer conductors and equipment suc as soar panes and inverters operates more efficienty and drops off wit i
28、ncreasing operating temperature of equipment inay ground snow cover can increase soar power production by refecting soar energy from te ground into soar panes Soar potovotaic power is a passive generation tecnoogy Soar power generation is a function of sunigt magnitude and duration Wen te sun sines
29、soar potovotaic power systems generate power Wen tere is no sunigt no power is produced Soar power generation cannot be increased in response to an increase in te oad Once a soar potovotaic power system is instaed and activated tere is no contro over ow muc soar power is generated onsequenty soar po
30、wer generation cannot be predicted at any given time Soar power generation owever can be accuratey predicted over a reativey ong period of time s a passive generation tecnoogy soar panes ony produce power wen exposed to sunigt and cannot store energy for ater use or grid connected systems soar power
31、 is ony avaiabe wen te eectric utiity grid is operationa !ybrid soar potovotaic power systems ave battery bac?up and are capabe of stand aone operation wen te eectric utiity grid is not avaiabe Off grid or stand aone soar potovotaic power systems require energy storage batteries and or aternative po
32、wer generation sources to provide power during nondayigt ours In genera soar panes must be ocated cear of obstructions and sadows tat can significanty reduce soar power production Soar panes must be ocated in areas wit sun exposure for most ours of te day Soar panes soud be oriented towards te sun a
33、nd tited at an ange tat maximizes soar power production Potovotaic power systems convert soar radiation into eectrica energy and deiver tat power to te eectrica power distribution system at te point of connection of te system Soar panes transform soar radiation into votage Soar panes are interconnec
34、ted as one or more soar arrays and suppy votage to one or more inverters Te inverter converts votage into an votage waveform tat is compatibe wit te eectrica distribution system deivering power to te grid Te inverter bot monitors contros and protects te potovotaic power system and te eectrica power N #% $% #&!i# # i#i#i# $v$!i $*% +&“&
