Renewable Energy Technologies for Federal Facilities

Transcription

1 Renewable Energy Technologes for Federal Facltes Ths report was prepared as an account of work sponsored by an agency of the Unted States Government. Nether the Unted States Government nor any agency thereof, nor any of ther employees, makes any warranty, express or mpled, or assumes any legal lablty or responsblty for the accuracy, completeness, or usefulness of any nformaton, apparatus, product, or process dsclosed, or represents that ts use would not nfrnge prvately owned rghts. Reference heren to any specfc commercal product, process, or servce by trade name, trademark, manufacturer, or otherwse does not necessarly consttute or mply ts endorsement, recommendaton, or favorng by the Unted States Government or any agency thereof. The vews and opnons of authors expressed heren do not necessarly state or reflect those of the Unted States_Governmentor_any-agency-thereof. Photovoltacs Convertng Sunlght nto Electrcty Serves Vared Power Needs Photovoltac (or PV) cells are devces that use semconductormateral to convert sunlght drectly nto electrcty. ndvdual solar cells, most commonly squares of slcon, are wred together and lamnated wthn a thn, protectve glass case to make a module. n other cases, a very thnlayer of noncrystallne slcon s coated on an nexpensve base. Though the thn-flm materal s less effcent at convertng sunlght to electrcty compared wth other systems, ts low cost and smplctyare perfect characterstcs for certan applcatons. These modules can then be joned to form PV arrays. The amount of electrcty generated by an array ncreases as more modules are added. PV systems range from very smple to complex. They can also be ether remote or connected to the electrc utlty grd. n remote (or off-grd) applcatons, PV power s ndependent of exstng utlty lnes and power grds. There are numerous examples of cost-effectve PV applcatons wthn the federal government today, most of whch are off-grd. The smplest PV system generates drectcurrent electrcty when the sun s shnng and runs equpment such as water pumps or fans. A power nverter can be used to convert drect current to alternatng current. And for powerng equpment n remote locatons, PV systems nclude batteres that store electrcty for use at nght or when the sun sn t shnng. The prmary uses for PV today are for telecommuncatons, securty and lghtng systems, water pumps, and load management. n some cases, power must be avalable on demand, or perhaps the electrcty requred occasonally exceeds the PV system s supply. Here, an electrc generator can work effectvely wth PV to supply the load. Remote locatons where loads are currently suppled by desel generators alone are good canddates for PV systems wth generators. Stes n natonal parks and natonal forests present good opportuntes for PV/hybrd systems. PV systems have many benefts: Portanbl&-can move PV unts easly to other locatons Hgh relabltt,l--pv modules operate relably for long perods of tme wth vrtually no mantenance Low operafng costs-fuel s free, and there are no movng parts Low envronmental mpact-nonpollutng and quet Sfand-aloneazpablhpfmremofe areas not served by a utlty power grd Modularfy-energy output can easly be ncreased or decreased by changng the number of panels Safe&-not flammable VersafltzJ-approprate for vrtually any clmate. What are the opportuntes? Photovoltacs should be consdered for any remote applcaton wth a daly electrcalload of a few watt-hours up to about 00 klowatt-hours.

2 What are the mportant terms? Balance of Sysfem-all components and factors other than the PV modules that contrbute of the cost of the system: desgn costs, land, ste preparaton, system nstallaton,support structures, power condtonng, operaton and mantenance costs, and ndrect storage. Break-Even-the cost of a PV system at whch the value of electrcty t produces exactly equals the cost of electrcty from an alternatvesource plus the delvery of ths electrcty to the ste. A break-even dstance s the dstance a power lne can be extended to match the nstallaton cost of PV. Concentrrrtor Collector-a PV module that uses optcal elements to ncrease the amount of sunlght strkng a PV cell, thus yeldng better effcences than flat-plate systems. Concentratng arrays must track the sun and use only the drect sunlght because dffuse lght cannotbe focused onto the PV cells. Effccbzcy-the percentage of avalable sunlght converted to electrcty by a module or cell. Techncally, ths s the rato of electrc power produced by a cell at any nstant to the power of the sunlght strkng the cell. Flat-Plnfe Away-a PV array that conssts of non-concentratng elements. t uses drect and dffuse sunlght, but f the array s fxed n poston, some porton of the drect sunlght s lost because of oblque sun-angles n relaton to the array. Peak Waft-maxmum "rated" output of a cell, module, or system. The amount of power a PV devce wll produce at noon on a clear day wth the sun approxmately overhead when the cell s facng drectly toward the sun. relablty of the utlty's power may be too low for a partcular applcaton. Or a federal agency may have hgher electrcty charges for mdday use of electrcty. The Natonal Park Servce has 455 exstng PV systems prmarly assocated wth equpment for montorng resources. And other cost-effectve, wdely demonstrated resdental and commercal of-grd applcatons nclude Street lghts for hghways Offshore drllng platforms Campgrounds and marnas Water-supply dsnfecton Remote-area fans and lghts Remote montorng equpment Communcatons equpment/ facltes (e.g., emergency roadsde phones, mcrowave repeater statons) Weather statons Cathodc protecton Hghway/warnng sgns Fre watch towers Landscape lghtng Securty systems Lvestock waterng pumps and rrgatonsystems Transmsson tower beacons Emergency power durng crses. What s requred? Modules need to face south and be unshaded Modules can be mounted on the applcaton tself, on the roof, or on the ground Batteres requre mantenance and are usually needed to meet peak loads or nghttmeusage The system needs a power nverter f the load requres alternatng current PV system must be evaluated on cost, system performance, system relablty, and mantenance requrements. What does t cost? On a frst-cost bass, PV systems' nstalled costs can be less than the cost of utlty servce. For larger loads where utlty power exsts, PV may stll be applcable. For example, the On a 20-year lfe-cycle cost bass, the cost of a remote PV system ranges from 25e-5Oc per klowatt-hour. For off-grd stes, there are numerous examples n the federal government where PV s more cost effectve than the alternatve fuel sources. Also, PV equpment s avalable from companes lsted on the General Servce Admnstraton's Federal Supply Schedule. For More nformaton For addtonal nformaton about photovoltacs, contact: John Thornton Natonal Renewable Energy 67Cole Boulevard Golden, CO (303) Hal Post PV Desgn Assstance Center Sanda Natonal Albuquerque, NM (505) Keth h a n d Solar Energy ndustres Assocaton 22 C Street, NW, 4th Floor Washngton, DC 2000 (202) To nqure about renewables desgn assstance avalable through FEMP, contact: ' j Nancy Carlsle Natonal Renewable Energy 67Cole Boulevard Golden, CO (303) FEMP Help Lne: Fax: hternet: Produced for the U.S.Department of Energy (DOE)by the Natonal Renewable Energy, a DOE natonal laboratory DE DOE/GO A revson of NREL/TM May 996 #* p mw Prnted wth a renewablesource nk on paper contanngatleast 50%wastepaper, ndudng20%postconsumerwaste j

3 DSCLAMER Portons of ths document may be llegble n electronc mage products. mages are produced from the best avalable orgnal document.

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5 Renewable Energy Technologes for Federal Facltes Photovoltacs Convertng Sunlght nto Electrcty Serues Vared Power Needs Photovoltac (or PV) cells are devces that use semconductormateral to convert sunlght drectly nto electrcty. ndvdual solar cells, most commonly squares of slcon, are wred together and lamnated wthn a thn,protectve glass case to make a module. n other cases, a very thn layer of noncrystallne slcon s coated on an nexpensve base. Though the thn-flm materal s less effcent at convertng sunlght to electrcty compared wth other systems, ts low cost and smplctyare perfect characterstcs for certan applcatons. These modules can then be joned to form PV arrays. The amount of electrcty generated by an array ncreases as more modules are added. PV systems range from very smple to complex. They can also be ether remote or connected to the electrc utlty grd. n remote (or off-grd) applcatons, PV power s ndependent of exstng utlty lnes and power grds. There are numerous examples of cost-effectve PV applcatons wthn the federal government today, most of whch are off-grd. The smplest PV system generates drectcurrent electrcty when the sun s shnng and runsequpment such as water pumps or fans. A power nverter can be used to convert drect current to alternatng current. And for powerng equpment n remote locatons, PV systems nclude batteres that store electrcty for use at nght or when the sun sn t shnng. The prmary uses for PV today are for telecommuncatons, securty and lghtng systems, water pumps, and load management. n some cases, power must be avalable on demand, or perhaps the electrcty requred occasonally exceeds the PV system s supply. Here, an electrc generator can work effectvely wth PV to supply the load. Remote locatons where loads are currently suppled by desel generators alone are good canddates for PV systems wth generators. Stes n natonal parks and natonal forests present good opportuntes for PV/hybrd systems. PV systems have many benefts: Porfaablty-can move PV unts easly to other locatons Hgh relnblty-pv modules operate relably for long perods of tme wth vrtually no mantenance Low operatng costs-fuel s free, and there are no movng parts Low envronmenfnl mpact-nonpollutng and quet Stand-alonecapablhpfmremote arms not served by a utlty power grd Modularty-energy output can easly be ncreased or decreased by changng the number of panels Safety-not flammable Versntlty-approprate for vrtually any clmate. PV-powered securty lghtng at Rooseuelt Lake n Arzona. Photovoltacs should be consdered for any remote applcaton wth a daly electrcalload of a few watt-hours up to about 00 klowatt-hours. U.S. Department of Enerw What are the opporhmtes?

6 What are the mportant terms? Balance of System-all components and factors other than the PV modules that contrbuteof the cost of the system: desgn costs, land, ste preparaton, system nstallaton,support structures, power condtonng, operaton and mantenance costs, and ndrect storage. Break-Even-the cost of a PV system at whch the value of electrcty t produces exactly equals the cost of electrcty from an alternatvesource plus the delvery of ths electrcty to the ste. A break-even dstance s the dstance a power lne can be extended to match the nstallaton cost of PV. Concentrator Collector-a PV module that uses optcal elements to ncrease the amount of sunlght strkng a PV cell, thus yeldng better effcences than flat-plate systems. Concentratng arrays must track the sun and use only the drect sunlght because dffuse lght cannot be focused onto the PV cells. Efckncy-the percentage of avalable sunlght converted to electrcty by a module or cell. Techncally, ths s the rato of electrc power produced by a cell at any nstant to the power of the sunlght strkng the cell. Flat-Plute Array-a PV array that conssts of non-concentratng elements. t uses drect and dffuse sunlght, but f the array s fxed n poston, some porton of the drect sunlght s lost because of oblque sun-angles n relaton to the array. Peak Watt-maxmum "rated" output of a cell, module, or system. The amount of power a PV devce wll produce at noon on a clear day wth the sun approxmately overhead when the cell s facng drectly toward the sun On a frst-cost bass, PV systems' nstalled costs can be less than the cost of utlty servce. For larger loads where utlty power exsts, PV may stll be applcable.for example, the relablty of the utlty's power may be too low for a partcular applcaton. Or a federal agency may have hgher electrcty charges for mdday use of electrcty. The Natonal Park Servce has 455 exstng PV systems prmarly assocated wth equpment for montorng resources. And other cost-effectve, wdely demonstrated resdental and commercal 0f-p.d applcatons nclude Street lghts for hghways Offshore drllng platforms Campgrounds and marnas Water-supply dsnfecton Remote-area fans and lghts Remote montorng equpment Communcatons equpment/ facltes (e.g., emergency roadsde phones, mcrowave repeater statons) Weather statons Cathodc protecton Hghway/warnng sgns Fre watch towers Landscape lghtng Securty systems Lvestock waterng pumps and rrgaton systems Transmsson tower beacons Emergency power durng crses. What s requred? Modules need to face south and be unshaded Modules can be mounted on the applcaton tself, on the roof, or on the ground Batteres requre mantenance and are usually needed to meet peak loads or nghttmeusage The system needs a power nverter f the load requres alternatng current PV system must be evaluated on cost, system performance, system relablty, and mantenance requrements. What does t cost? On a 20-year lfe-cycle cost bass, the cost of a remote PV system ranges from per 4 klowatt-hour. For off-grd stes, there are numerous examples n the federal government where PV s more cost effectve than the alternatve fuel sources. Also, PV equpment s avalable from companes lsted on the General Servce Admnstraton's Federal Supply Schedule. J For More nformaton b For addtonal nformaton about photovoltacs, contact: John Thomton Natonal Renewable Energy 67Cole Boulevard Golden, CO (303) Hal Post PV Desgn Assstance Center Sanda Natonal Albuquerque, NM (505) Sethb a n d Solar Energy ndustres Assocaton 22 C Street, NW, 4th Floor Washngton, DC 2000 (202) To nqure about renewables desgn assstance avalable through FEMP, contact: Nancy Carlsle Natonal Renewable Energy 67 Cole Boulevard Golden, CO (303) FEW Help Lne: Fax: nternet: Produced for the U.S.Department of Energy (DOE)by the Natonal Renewable Energy, a DOE natonal laboratory DE DOE/GO A revson of NREL/TP May 996 q* Prnted wtha renewablesource nkon paper Fontanngat least 50%wastepaper, ndudng20% postconsumerwaste '