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www.iaei.org January.February2008IAEI NEWS 79

IAEI The Other Code: The National Electrical Safety Code

Aswesawinpart1othisseries, it is tough to makealternative electric sources

economicalwhenyouaretryingtooperate a completely independentsystem.Usuallytheonlytimepeo-pleinstallsuchsystemsiswhenthenormalelectricserviceisnotavail-able. Utilizing alternative energysources as a supplement to your

normal electric service is a verydierentworld.Renewableenergysourcesthatoperateinparallelwiththeutilitycanbeveryeconomical.Inthesesystems,thegoalotheal-ternativeenergysourceistoreduceexpenses.

Parallel SystemsAll parallel system designs mustbeapprovedbytheelectricutilitybeoreinstallation.Someutilities

requirethecustomertoinstallsophisticatedandexpen-siveprotectionsystemsorparalleloperation.Iunder-standthatsomeutilitiesdonotallowparalleloperation.In most parallel systems involving alternative energysourceslikesolarandwind,theinteracebetweentheutilitysourceandthecustomerssourceisusuallyanin-verterdesignedorparalleloperation.Solarvoltaiccellsandmostsmallwindmillsproducelowvoltagedcpower.Teinverterconvertsthelowvoltagedctotheutility60Hz.acservicevoltage.Forresidentialcustomers,someutilitiesallowthekWhmeteronthesideothecustom-

ershousetorunbackwardswhenthecustomerissellingexcesspowertotheutilityaslongasthecustomerusageeachmonthismorethantheysell.Teutilitywantstosendoutabillnotacheck.TisisthebestsituationorthecustomerbecauseeverykWhhegeneratesisworth

whatthecustomerpaysorenergy.Someutilitiesinstallseparatemeters,onetomeasure

howmuchenergythecustomerpurchasedandonetomeasurehowmuch energythe customersold. Inthiscase,themetersaremodiedsotheywillnotoperatebackwards and the utility usually purchases energy

If Electricity Is So

Expensive, Why DontYou Buy a Generator?

Part2,ParallelSystemsbyDavidC.Young,P.E.

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80 IAEI NEWSJanuary.February2008 www.iaei.org

IAEI The Other Code: The National Electrical Safety Code

romthecustomerataratewellbelowthatwhichthecustomer is paying tobuy energy. Teutilityusuallypurchasesenergyromthecustomeratthesameratetheypaylargegeneratingcompaniesorenergy.

Safetyoprotecttheutilitylinemenromshockandothercus-tomersequipment romdamage, mostutilities requirecustomerswiththeirowngenerationautomaticallytodis-connectromtheutilitysourceanytimetheutilitysourceislost.Tisiswherethesophisticatedrelayingcomesin.

Government IncentivesInsomestates,alternativeenergysystemscanbeeco-nomicalbecauseothetaxcreditsorstategrantsavail-abletopeopleandcompanieswhoinstallsuchsystems.

IunderstandthatCaliorniaoersthegreatestbenets.Massachusetts and Delaware are examples o stateswheregrantsareavailableuptotypercentothecostotheinstallation.Contactyourstateenergyofcetoseewhatincentivesareavailableinyourstate.HundredsohomeownersandcompaniesallovertheU.S.aretak-ingadvantageothegrantsandtaxincentives.

According to an IEEE SpectrummagazineOctober2007article,TeGreeningoGoogle,thelargestcor-porateinstallationosolarpanelsinNorthAmericaisaGoogleofcecomplexinCaliornia.TeGooglesolar

voltaicarraywillproduce1.6millionwattsoelectric-itybytheendothisyear.Morethanninethousand(9,509) parallelsolarsystems(101millionwatts)wereinstalledintheU.S.in2006.Seventypercent othese

systemswhereinstalledinCaliornia.Expertsestimatethat a solar installation costs between$3 and $5 per

wattinCaliorniaandbet ween$6and$10perwatt intherestothecountry.

Electricalcontractorsalloverthecountryarenowoer-inginstallationosolarsystemsorhomesandbusinesses.Onecontractorinmyareaworkswiththeutility,installsacompletelyautomaticsystemandevenllsoutthepa-perworkortheownertogetthegrantromthestate.Allthecustomerhastodoissignthecontractandwriteoutacheck.Insomestates,therearecompanieswhowillinstall

andmaintainsolarpanelsonyourrooorree.Allyoudoissigna15-yearcontracttopurchasetheenergyromthesolarpanelsataxedrate,whichislessthanwhatyouarepresentlypayingorenergyromyourlocalutility.

Te FutureWeneedtoencourage ourstategovernmentsto createtaxcreditsand/orstategrantslikeCaliornia,NewJer-sey, Massachusetts and Delaware to promote alterna-tive energy generationand conservation.In Germany,homeownersarepaying35centsperkWhorelectricenergy.Forthenexttwentyyears,theGermangovern-

mentpromisestopaytycentsperkWhorenergyproducedbyhomeowners and companies who installsolarandwindgenerators.TerearearmersinGerma-nywhohavecoveredtheireldswithsolarpanels.Teyarenowsolararmers.Mostothemmakemoremoneyasasolararmerthantheyeverdidasacroporcattlearmer.MosthousesinGermanyhavesolarpanelsontheirroosandmoreimportantly,thewholecountryisreducingairpollutionandrapidlybecominglessdepen-dantoncoal,oil,gasandnuclear.Formoreinormation,seetheNOVAspecialSolar Energy, Saved by the Sun.

Pleasesendmeyourcommentsonthisarticle.Iyouhavegeneralquestionsaboutelectricity,electricpowerdistribution or the National Electrical Saety Code(NESC), please e-mail me at dave@daveyoungengi-neering.comorcallmeat302-633-1044.

Dave is an electric power consulting engineer and president of YoungEngineering, Inc. of Wilmington, Delaware. Dave has been workingwith and teaching all aspects of the NESC and electric power distribu-tion for over 35 years. Dave teaches electric power at the University ofDelaware and is a member of the NESC Interpretations Subcommit-tee and the Overhead Line Clearances Subcommittee. Dave is also aninspector member of the IAEI.