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Building-Integrated PhotovoltaicDesigns for Commercial andInstitutional Structures

A Sourcebook for ArchitectsPatrina Eiffert, Ph.D.Gregory J. Kiss

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AcknowledgementsBuilding-Integrated Photovoltaics for Commercial and Institutional Structures: ASourcebook for Architects and Engineerswas prepared for the U.S. Department of Energy's (DOE's) Office of Power Technologies, Photovoltaics Division, and the

Federal Energy Management Program. It was written by Patrina Eiffert, Ph.D.,of the Deployment Facilitation Center at DOE’s National Renewable EnergyLaboratory (NREL) and Gregory J. Kiss of Kiss + Cathcart Architects.

The authors would like to acknowledge the valuable contributions of SheilaHayter, P.E., Andy Walker, Ph.D., P.E., and Jeff Wiechman of NREL, and AnneSprunt Crawley, Dru Crawley, Robert Hassett, Robert Martin, and Jim Rannels of DOE. They would also like to thank all those who provided the detailed design briefs, including Melinda Humphry Becker of the Smithsonian Institution,Stephen Meder of the University of Hawaii, John Goldsmith of Pilkington SolarInternational, Bob Parkins of the Western Area Power Administration, SteveCoonen of Atlantis, Dan Shugar of Powerlight Co., Stephen Strong and BevanWalker of Solar Design Associates, Captain Michael K. Loose, Commanding

Officer, Navy Public Works Center at Pearl Harbor, Art Seki of Hawaiian ElectricCo., Roman Piaskoski of the U.S. General Services Administration, Neall Digert,Ph.D., of Architectural Energy Corporation, and Moneer Azzam of ASE Americas,Inc.

In addition, the authors would like to thank Tony Schoen, Deo Prasad, PeterToggweiler, Henrik Sorensen, and all the other international experts from theInternational Energy Agency’s PV Power Systems Program, TASK VII, for theirsupport and contributions.

Thanks also are due to staff members of Kiss + Cathcart and NREL for theirassistance in preparing this report. In particular, we would like to acknowledgethe contributions of Petia Morozov and Kimbro Frutiger of Kiss + Cathcart, andRiley McManus, student intern, Paula Pitchford, and Susan Sczepanski of NREL.

On the cover: Architect’s rendering of the HEW Customer Center in Hamburg, Germany,showing how a new skin of photovoltaic panels is to be draped over its facade and forecourt(architects: Kiss + Carthcart, New York, and Sommer & Partner, Berlin).

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ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

Design Briefs4 Times Square . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Thoreau Center for Sustainability . . . . . . . . . . . . . . . . . . . . . . . . . . .7

National Air and Space Museum . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

Ford Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Western Area Power Administration . . . . . . . . . . . . . . . . . . . . . . .24

Photovoltaic Manufacturing Facility . . . . . . . . . . . . . . . . . . . . . . .28

Yosemite Transit Shelters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34Sun Microsystems Clock Tower . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

State University of New York, Albany . . . . . . . . . . . . . . . . . . . . . .38

Navajo Nation Outdoor Solar Classroom . . . . . . . . . . . . . . . . . . . .40

General Services Administration, Williams Building . . . . . . . .42

Academy of Further Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

Discovery Science Center . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

Solar Sunflowers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50Ijsselstein Row Houses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Denver Federal Courthouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54

BIPV Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58

BIPV Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69

Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70

Appendix A: International Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

Appendix B: Contacts for International Energy AgencyPhotovoltaic Power Systems Task VII—Photovoltaics in theBuilt Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Appendix C: Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

About the Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

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IntroductionBuilding-integrated photovoltaic (BIPV) electric power systems not only produce electricity, theyare also part of the building. For example, a BIPV skylight is an integral component of the building envelope as well as a solar electric energy system that generates electricity for the building. Thesesolar systems are thus multifunctional construction materials.

The standard element of a BIPV system is the PV module. Individual solar cells are interconnectedand encapsulated on various materials to form a module. Modules are strung together in anelectrical series with cables and wires to form a PV array. Direct or diffuse light (usually sunlight)shining on the solar cells induces the photovoltaic effect, generating unregulated DC electricpower. This DC power can be used, stored in a battery system, or fed into an inverter thattransforms and synchronizes the power into AC electricity. The electricity can be used in thebuilding or exported to a utility company through a grid interconnection.

A wide variety of BIPV systems are available in today's markets. Most of them can be groupedinto two main categories: facade systems and roofing systems. Facade systems include curtainwall products, spandrel panels, and glazings. Roofing systems include tiles, shingles, standing seam products, and skylights. This sourcebook illustrates how PV modules can be designed asaesthetically integrated building components (such as awnings) and as entire structures (such asbus shelters). BIPV is sometimes the optimal method of installing renewable energy systems inurban, built-up areas where undeveloped land is both scarce and expensive.

The fundamental first step in any BIPV application is to maximize energy efficiency within thebuilding’s energy demand or load. This way, the entire energy system can be optimized.Holistically designed BIPV systems will reduce a building’s energy demand from the electric

utility grid while generating electricity on site and performing as the weathering skin of thebuilding. Roof and wall systems can provide R-value to diminish undesired thermal transference.Windows, skylights, and facade shelves can be designed to increase daylighting opportunitiesin interior spaces. PV awnings can be designed to reduce unwanted glare and heat gain. Thisintegrated approach, which brings together energy conservation, energy efficiency, building envelope design, and PV technology and placement, maximizes energy savings and makes themost of opportunities to use BIPV systems.

It is noteworthy that half the BIPV systems described in this book are on Federal buildings. This isnot surprising, however, when we consider these factors: (1) the U.S. government, with more thanhalf a million facilities, is the largest energy consumer in the world, and (2) the U.S. Departmentof Energy (DOE) has been directed to lead Federal agencies in an aggressive effort to meet thegovernment’s energy-efficiency goals. DOE does this by helping Federal energy managers identifyand purchase the best energy-saving products available, by working to increase the number andquality of energy projects, and by facilitating effective project partnerships among agencies,utilities, the private sector, and the states.

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Because it owns or operates so many facilities, the U.S. government has an enormous number of opportunities to save energy and reduce energy costs. Therefore, the Federal Energy ManagementProgram (FEMP) in DOE has been directed to help agencies reduce energy costs, increase theirenergy efficiency, use more renewable energy, and conserve water. FEMP's three major work areasare (1) project financing; (2) technical guidance and assistance; and (3) planning, reporting, andevaluation.

To help agencies reach their energy-reduction goals, FEMP’s SAVEnergy Audit Program identifiescost-effective energy efficiency, renewable energy, and water conservation measures that can beobtained either through Federal agency appropriations or alternative financing. FEMP's national,technology-specific performance contracts help implement cutting-edge solar and other renewableenergy technologies. In addition, FEMP trains facility managers and showcases cost-effectiveapplications. FEMP staff also identify Federal market opportunities and work with procurement

organizations to help them aggregate purchases, reduce costs, and expand markets. All these activities ultimately benefit the nation by reducing building energy costs, saving taxpayersmoney, and leveraging program funding. FEMP’s activities also serve to expand the marketplacefor new energy-efficiency and renewable energy technologies, reduce pollution, promoteenvironmentally sound building design and operation, and set a good example for state and localgovernments and the private sector.

This sourcebook presents several design briefs that illustrate how BIPV products can be integratedsuccessfully into a number of structures. It also contains some basic information about BIPV andrelated product development in the United States, descriptions of some of the major software design

tools, an overview of international activities related to BIPV, and a bibliography of pertinentliterature.

The primary intent of this sourcebook is to provide architects and designers with useful informationon BIPV systems in the enclosed design briefs. Each brief provides specific technical data about theBIPV system used, including the system’s size, weight, and efficiency as well as number of invertersrequired for it. This is followed by photographs and drawings of the systems along with generalsystem descriptions, special design considerations, and mounting attachment details.

As more and more architects and designers gain experience in integrating photovoltaic systemsinto the built environment, this relatively new technology will begin to blend almost invisibly into

the nation’s urban and rural landscapes. This will happen as BIPV continues to demonstrate acommercially preferable, environmentally benign, aesthetically pleasing way of generating electricity for commercial, institutional, and many other kinds of buildings.

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Close-up view of curtain wall illustrates that BIPV panels (dark panels) can be mountedin exactly the same way as conventional glazing (lighter panels).

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4 design briefs: 4 Times Squar

4 Times SquareLocation: Broadway and 42nd Street, New York City, New YorkOwner: Durst CorporationDate Completed: September 1999 Architect & Designer: Fox & Fowle Architects, building architects;

Kiss + Cathcart Architects, PV system designersPV Structural Engineers:

FTL/HappoldElectrical Engineers: Engineers NYTradesmen Required: PV glazing done by shop labor at curtain wall fabricator Applicable Building Codes: New York City Building Code Applicable Electric Codes: New York City Electrical Code and National Electric CodePV Product: Custom-sized BIPV glass laminateSize: 14 kWpProjected System Electrical Output: 13,800 kWh/yrGross PV Surface Area: 3,095 ft 2

PV Weight: 13.5 lb/ft 2

PV Cell Type: Amorphous siliconPV Module Efficiency: 6%PV Module Manufacturer: Energy Photovotaics, Inc.Inverter Number and Size: Three inverters; two 6 kW (Omnion Corp.), one 4 kW (Trace Engineering)Inverter Manufacturers: Omnion Corp. and Trace EngineeringInterconnection: Utility-Grid-Connected

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DescriptionThe tallest skyscraper built in New YorkCity in the 1990s, this 48-story office towerat Broadway and 42nd Street is a some-what unusual but impressive way todemonstrate "green" technologies. Itsdevelopers, the Durst Organization, wantto show that a wide range of healthybuilding and energy efficiency strategiescan and should be incorporated into realestate practices.

Kiss + Cathcart, Architects, are consul-tants for the building tower’s state-of-the-art, thin-film BIPV system. Working incollaboration with Fox and Fowle, archi-tects for the base building, Kiss + Cathcarthave designed the BIPV system to func-tion as an integral part of the tower's

curtain wall. This dual use makes it oneof the most economical solar arraysever installed in an urban area. EnergyPhotovoltaics of Princeton, New Jersey,developed the custom PV modules tomeet rigorous aesthetic, structural, andelectrical criteria.

Traditionally, solar technologies havebeen considered economical only inremote areas far from power grids or inareas with an unusually high amount of sunlight. Advances in PV efficiency are

overturning these assumptions, allowingsolar electricity to be generated cost-effectively even in the heart of the city.In fact, PV is the most practical means of generating renewable electricity in anurban environment. Further, BIPV can bedirectly substituted for other claddingmaterials, at a lower material cost thanthe stone and metal it replaces. As thefirst major commercial application ofBIPV in the United States, 4 Times Squarepoints the way to large-scale productionof solar electricity at the point of greatest

use. The next major market for PV maywell be cities like New York that have bothhigh electricity costs and high-qualitybuildings.

Special Design ConsiderationsThe south and east facades of the 37ththrough the 43rd floor were designatedas the sites for the photovoltaic "skin."BIPV was incorporated into the designafter the tower’s general appearancehad already been decided upon, so the

design briefs: 4 Times Square

BIPV panels have beenintegrated into thecurtain wall instead of conventional glassspandrel panels on the37th through the 43rdfloor.

The custom-made BIPV panels are visible in thissidewalk view fromBroadway.

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installation was made to harmonize withthe established design concept.

PV System ConfigurationThe PV modules replace conventionalspandrel glass in the south and east

facades. There are four different sizesof modules, and they correspond to thespandrel sizes established earlier in thedesign process.

PV Module Mounting and Attachment DetailsThe PV modules are attached to the build-ing structure in exactly the same way thatstandard glass is attached. The glassunits are attached with structural siliconeadhesive around the back edge to an alu-minum frame. An additional silicone bead

is inserted between the edges of adjacentpanels as a water seal.

There is a separate electrical system foreach facade. Each system consists of twosubsystems, feeding two 6-kW invertersand one 4-kW inverter. The larger invert-ers serve the two large-sized PV modules,which have electrical characteristics thatare different from those of the smallerones. Using multiple inverters enables thesystem to perform more efficiently. Theinverters are located in a single electrical

closet at the core of the building. The ACoutput of the inverters is transformedfrom 120 V to 480 V before being fed intothe main electrical riser.

6 design briefs: 4 Times Square

4 Times Square during construction

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Location: Presidio National Park, Building 1016, San Francisco, CaliforniaOwner: U.S. Department of Interior, National Park ServiceDate Completed: May 1996 Architect & Designer:

Tanner, Leddy, Maytum, StacyStructural and Electrical Engineers: Equity BuildersTradesmen Required: Glaziers Applicable Building Codes: California structural and seismic codes Applicable Electric Codes: National Electric CodePV Product: Roof-integrated, translucent glass-laminate skylightSize: 1.25 kWpProjected System Electrical Output: 716.4 kWh/yr/ACGross PV Surface Area: 215 ft2

PV Weight: 8 lb/ft 2

PV Cell Type: Polycrystalline siliconPV Efficiency: 11% cell, 7% modulePV Module Manufacturer: Solar Building Systems, Atlantis EnergyInverter Size: 4 kWInverter Manufacturer and Model: Trace Engineering Model 4048Interconnection: Utility-Grid-Connected

design briefs: Thoreau Center for Sustainability

Thoreau Center for Sustainability

Presidio National Park, Building 1016

The first application for integrating photovoltaicsinto a Federal building is theskylighted entryway of theThoreau Center in PresidioNational Park.

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DescriptionThe Greening of the Presidio demon-strates the impact of successful partner-ships between the private and publicsector. The Thoreau Center for Sustain-ability is a historic building, located in theNational Historic Landmark District of thePresidio in San Francisco, California. Thegoal of transforming this historic buildinginto an environmentally responsive struc-ture produced an opportunity to applyprinciples of sustainable design andarchitecture and educate the public aboutthem. Within this building rehabilitationproject, materials selected for the renova-tion included recycled textile materials,recycled aluminum, recycled newsprint,recycled glass, and wood grown andharvested sustainably.

The environmentally friendly strategyincluded reducing energy consumptionthrough a Demand Side Management(DSM) Program with the local utility com-pany, PG&E. The building has a highly effi-cient direct/indirect lighting system withtranslucent office panels to allow innerzones to borrow daylight from the perime-ter. The building is heated by an efficientmodular boiler and is cooled by naturalventilation. The BIPV system is a highlyvisible sustainable building feature. Thedemonstration of this power system byDOE FEMP, the National RenewableEnergy Laboratory (NREL), and numerousprivate-sector partners illustrates thatBIPV is a technically and economicallyvaluable architectural element fordesigners.

The skylit entryway of the Thoreau Centerfor Sustainability at Presidio NationalPark was the first demonstration in theUnited States of the integration of photo-voltaics into a federal building. Laminated

to the skylight glass are photovoltaic cellsthat produce electricity and also serveas a shading and daylighting design ele-ment. Atlantis Energy provided custom-manufactured PV panels and the systemdesign and integration for this project.The firm was joined by constructionspecialists who made it possible totransform this historic building into anenvironmentally responsive structure.

The solar electricity generated in thePV system in the skylight offsets power

provided by the utility, thereby conservingfossil fuels and reducing pollution.Converting the DC electricity to AC, thesystem can produce about 1300 wattsduring periods of full sun. The systemis fully automatic and requires virtuallyno maintenance. Like other PV systems,it has no moving parts, so this solargenerating system provides clean, quiet,dependable electricity.

The entry area into the Thoreau Center isa rectangular space with a roof slopingslightly to the east and west. The roof isconstructed entirely of overhead glazing,similar to a large skylight. PV cells arelaminated onto the 200 square feet of available overhead glazing to produceapproximately 1.25 kW of electricity understandard operating conditions. The PV-produced DC electric power is convertedto high-quality AC by a power-conditioningunit (inverter). After it is converted, thepower enters the building to be consumedby the building’s electrical loads.

Special Design ConsiderationsDesign and construction issues for therelatively small Thoreau Center systemwere similar in many ways to issuesinvolved with designing and constructingmuch larger systems. The panels for this

project were custom-manufactured byAtlantis Energy to meet the estheticrequirements of the architect. The square,polycrystalline PV cells are spaced farenough apart from one another to permitdaylighting and provide pleasant shad-ows that fall within the space. The amountof daylight and heat transfer throughthese panels was considered in determin-ing the lighting and HVAC requirementsfor the space. The panels themselveswere constructed to be installed in a stan-dard overhead glazing system framework.

The system is installed above seismic-code-approved skylight glazing. The day-lighting and solar gains through the PVmodules mounted above the skylight sys-tem do affect the building lighting andHVAC loads, but the modules do not alsoserve as the weathering skin of this build-ing envelope. Originally, the design calledfor the PV modules to replace the skylightunits. But during design approval, localbuilding code authorities were uncertainwhether the modules could meet seismiccode requirements. So the alternativedesign, stacking the skylights and themodules, was used instead.

To ensure that the glazing used in manu-facturing the PV panels was acceptableaccording to Uniform Building Codes

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The PV arrays produce electricity and serve as a daylighting designelement.

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This schematic drawing shows how the PV modules were attached above the conventional skylight glazing.

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(UBC), building code issues wereaddressed. Special arrangements weremade with the local electrical utility toensure that the grid-tied system wouldmeet safety requirements. Finally,installing the system required coordina-tion between the panel supplier, electri-cian, glass installer, and Presidio facilitiespersonnel.

PV System ConfigurationThe BIPV glazing system consists of 24 PVglass laminates. The spacing of the cellswithin the modules allows approximately17% of the sunlight into the entryway,reducing the need for electric lights. Themodules consist of 6-mm Solarphireglass, 36 polycrystalline silicon PV cells,

an ethylene-vinyl acetate coating, atranslucent Tedlar-coated polyester back-sheet, and two sealed and potted junctionboxes with a double pole plug connector.The PV cells are laminated in a 6-cell x 6-cell matrix. The minimum spacingbetween cells is 1.25 cm (1/2 in.). Thedimension of each module is 81 cm x 94 cm (32 in. x 37 in). The gross area of the entire structure is 18.8 m 2 (200 ft2 ).

The power produced by the system is con-verted to high-quality AC electricity andsupplements power supplied to the build-ing by the utility. The system is rated at1.25 kW. Each of the 24 PV modules gen-erates 8.5 V of DC power at approximately5.5 amps. Six modules per sub-array are

connected in series to feed the sine-waveinverter, which is configured to 48 V andrated at 4,000 W capacity.

PV Module Mounting and Attachment DetailsStructural upgrades were made to accom-modate the additional weight of the PVsystem. These added about $900 to thetotal cost, for structural components.

10 design briefs: Thoreau Center for Sustainability

This drawing shows how the photovoltaic skylight array was arranged. The total array area is 20.6 square meters.

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design briefs: National Air and Space Museum

National Air and Space MuseumLocation: Dulles Center, Washington, DCOwner: Smithsonian InstitutionDate Completed: Construction begun in 2000, scheduled for completion in 2003 Architect & Designer: HOK, Building Architects; Kiss + Cathcart Architects, PV System Designers;

Satish Shah, Speigel, Zamel, & Shah, Inc.Structural Engineers: N/AElectrical Engineers: N/ATradesmen Required: Building tradesmen Applicable Building Codes: BOCA, Metropolitan Washington Airport Authority Applicable Electric Codes: National Electric CodePV Product: Various BIPV systemsSize: To be determined for BIPV curtain wall, facades, and canopyProjected System Electrical Output: 15.12 kWh for the canopy systemGross PV Surface Area: 223 m2 for the canopy systemPV Weight: 5 lb/ft 2 for the canopy systemPV Cell Type: Polycrystalline cells, amorphous silicon film for various systemsPV Efficiency: Systems will range from 5% to 12%PV Module Manufacturer: Energy Photovoltaics, Inc., for the

canopy systemInverter Number and Size: To be determinedInverter Manufacturer & Model: To be determinedInterconnection: Utility-Grid-Connected

Project Overview: Axonometric

PV CanopyPV Curtain Wall

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The BIPV installations at theentryway will demonstratedifferent BIPV systems andtechnologies, such as thinfilms and polycrystallinesolar cells.

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DescriptionThe National Air & Space Museum(NASM) of the Smithsonian Institution isone of the most-visited museums in theworld. However, its current building onthe Mall in Washington, D.C., can accom-modate only a fraction of NASM’s collec-tion of historical air- and spacecraft.Therefore, a much larger expansion facil-ity is planned for a site adjacent to DullesAirport. Since the new facility will exhibittechnologies derived from space explo-ration, the use of solar energy, which haspowered satellites and space stationssince the 1950s, is especially fitting forthis new building.

Kiss + Cathcart, Architects, are undercontract to the National RenewableEnergy Laboratory as architectural-photovoltaic consultants to the

Smithsonian Institution. Working withthe Smithsonian and HOK Architects,Kiss + Cathcart is identifying suitableareas for BIPV, selecting appropriatetechnologies, and designing the BIPVsystems. For DOE FEMP, a partner in theproject, a primary goal is to demonstratethe widest possible range of BIPV applica-tions and technologies in one building.Construction should begin in 2000.

The NASM Dulles Center will serve asan exhibit and education facility. Its

core mission is to protect the nation’scollection of aviation and space-flight-related artifacts. It will also house thepreservation and restoration workshops

of the Air and Space Museum.The center’s design includes a large,hangar-style main exhibition space thatwill allow visitors to view the collectionsfrom two mezzanines as well as fromground level. It is estimated that morethan 3 million people will visit the centerannually to view aircraft, spacecraft, andrelated objects of historic significance,many of which are too large to display atthe National Air and Space Museum inWashington, D.C. The facility will set new

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Plan view of BIPV installation at entry areas

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The south- and west-facing facades of the entry hall will be glazed with polycrystalline glass laminates.

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standards for collections managementand the display of large, 20th-centuryfunctional objects.

Smithsonian staff are evaluating the inte-gration of a number of grid-connectedBIPV systems into the building. The NASMDulles Center will be a very large structure(740,000 ft 2 ), with commensurate energyand water requirements. As part of itseducational mission, the museum plansto exhibit hardware that points to thehistoric use of photovoltaic (PV) powersystems in space; the museum wouldalso like to demonstrate how that tech-nology can be used today in terrestrialapplications such as BIPV. To this end,the Smithsonian is evaluating the highlyvisible application of BIPV at this facilityto meet a portion of its energy require-ments. In this way, two objectives will be

met: (1) reduce the amount of energyrequired from the power grid, especiallyduring peak times, and thus conserveenergy and save operational funds, and(2) demonstrate the use of PV in a highlyvisible context in a much-visited Federalfacility.

Five BIPV subsystems could be demon-strated at the new NASM facility, includingthe south wall and skylight of the entry"fuselage," the roof of the restorationhangar and space shuttle hangar, thefacade of the observation tower, andawning canopies. The entry fuselagefigure clerestory windows will be a highlyvisible way of demonstrating PV to visi-tors approaching the center. Once in theentryway, visitors would also see thepatterns of shadow and light the frittedglass creates on the floor, thus focusing

visitors attention on the PV. Labels,exhibit material, and museum tour staff could further highlight the PV arrays andcall attention to the energy savings beingrealized. PV would also be used to powersome exhibit material exclusively. Therelated exhibit materials could highlightthe many connections between PV and

the field of space exploration and utiliza-tion, as well as today’s construction andbuilding industry.

14 design briefs: National Air and Space Museum

BIPV Canopy detail 1:10

Canopy:Structural Details

BIPV Canopy - section 1:60

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Thin-film BIPV glasslaminates will functionas the canopy.

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Fuselage detail illustrates patterns of polycrystalline glazing.

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Curtain wall details indicate how mullion channels will act as electrical conduits.

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The canopy plan and perspective demonstrate how shading and power output are combined in one architecturalexpression.

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Curtain walls typically will be 16 polycrystalline solar cells per panel, laminated between two clear glass panes.

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design briefs: Ford Island

Ford Island

Building 44, Pearl Harbor Naval Station

This illustration is a view of the building from the southwest corner; the dark areasrepresent the photovoltaic standing-seam metal roofing material.

Location: Honolulu, HawaiiOwner: U.S. Navy, Department of Defense, and Hawaiian Electric CompanyDate Completed: September 1999

Architect & Designer: Victor Olgyay, Fred Creager, and Stephen Meder, University of Hawaii, School ofArchitecture

Structural Engineers: Hawaiian Electric Co.Electrical Engineers: Hawaiian Electric Co.; Peter Shackelford, Renewable Energy Services, Inc., system integratorTradesmen Required: Roofers, electrical contractors Applicable Building Codes: Uniform Building Code Applicable Electric Codes: National Electric CodePV Product: Integrated standing seam metal roof Size: 2.8 kW DCProjected System Electrical Output : 9,720 kWh per monthGross PV Surface Area: 571 ft2

PV Weight: 4 lb/ft 2, with the roof PV Cell Type: Multijunction amorphous siliconPV Module Efficiency: 5%-6%PV Module Manufacturer: Uni-SolarInverter Number and Size: One, 4-kWInverter Manufacturer and Model: Trace SW 4048PVInterconnection: Utility-Grid-Connected

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DescriptionA partnership consisting of the U.S. Navy,Hawaiian Electric Co. (HECO), theUniversity of Hawaii, the U.S. DOE FederalEnergy Management Program (FEMP),and the Utility PhotoVoltaic Group (UPVG)was created in order to design and installa 2-kW, grid-intertied, BIPV retrofit sys-tem using the Uni-Solar standing seammetal roofing product and to monitor itsperformance for one year. The Universityof Hawaii School of Architecture designedand administered the project and a localutility, HECO, funded it. Additional con-struction cost support was supplied byFEMP, NREL, and the Navy. The utility andthe Navy determined the site, and theinstallation date was scheduled for thethird quarter of 1998 (Figure 1). HECO wasdesignated to be the client for the firstyear, after which the Navy will assumeownership of the system.

The tropical location (21° North) and thesite’s microclimate make it an ideal loca-tion for PV installations. Project plannersexpected an annual daily average of 5.4 peak sun hours and 20 to 25 in.(57 cm) of annual rainfall. This project, atthis particular site, will also be testing thelimits of the products used in the installa-tion. Monitoring the performance of the

PV system, the McElroy metal substrate,and the Trace inverter in a tropical marineenvironment will provide valuable perfor-mance information to guide the futuredevelopment and use of these products.

The total cost of this project was $92,000.This included design, procurement, roof removal and BIPV installation, and a yearof monitoring.

Special Design ConsiderationsThe context of this project is the navalindustrial site at Pearl Harbor NavalBase.The site contained a 90 ft x 52 ft(27.4 m x 15.8 m) open-wall boathousestructure. The existing roof of the struc-ture was made of box rib metal on trusses(Figure 2) in gable form, divided longitudinally on its east-west axis. The south

20 design briefs: Ford Islan

In this illustration, the dark areas represent amorphoussilicon laminates on standing seam metal roofing panels.

The array in mid-installation is shaded only by cloud cover.

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slope provides a 90 ft x 26 ft (27.4 m x 7.9 m) surface at a 5° incline. This half

of the roof measured approximately2,340 ft 2 (217 m2 ). The box rib roofingwas removed from the entire south-facingslope, and new standing seam pans,including 24 of the Uni-Solar SSR 120photovoltaic standing seam panels,replaced the original roofing.

Integrating the new metal roofing withthe existing roof posed several designand construction challenges. In addition,the longest panel that Uni-Solar could

provide is 20 ft (6.09 m) and the requiredrun is 26+ ft (8 m). This shortfall required

overlapped joints to be used on the endsof the panels and additional purlinesto be welded for support. Full-length,standing-seam panels and non-PV panelswere set in an alternating pattern withthe PV modules. This arrangementallowed the full-length pans to addstrength over the required lap joint ofthe shorter PV units.

The length limitation of the Uni-Solarpanels was a design deficiency of the

Uni-Solar product; unless new PV-to-metal laminating processes are devel-oped, this product will be substantiallylimited in metal roofing applications. Joining the panels to extend their lengthnot only increases material and labor

costs, it also provides opportunities forwater penetration and corrosion. The"galvalum" coating is cut away every-where the panel is modified. This exposesthe steel of the standing seam panel tothe marine environment. Therefore,McElroy, Uni-Solar’s metal roof supplier,will not warranty the product for marineapplications.

In addition, to match the paint of theexisting structure, McElroy required aminimum order to custom-paint the newroof panels. Therefore, about one-thirdmore roofing panels had to be purchasedthan were needed, and this increased theoverall project cost. The extra panelsturned out to be useful, however, sincemany were damaged during transport toHawaii.

The part of the roof to be retrofitted spansa dock area below. This presented stagingchallenges for the roofing and electricalcontractors. Along with restricted accessto the military base and the need to take abridge to the site, the location of the roof added to the complexity and costs of theproject. And the harsh marine environ-ment could have a corrosive effect on thearray and its components.

PV System ConfigurationThe system is rated at 2.175 kW AC(2.8 kW DC). The estimated system out-put is 9,720 kWh per month. The buildingis not independently metered. It is fed bythe Pearl Harbor grid, to which HECO supplies power. The estimated demand of thebuilding is about 12000 kWh per month.The energy generated by the PV systemwill feed but not meet the average loadsof this building.

PV Module Mounting and Attachment DetailsIntegrated connection follows standardmetal seam roof attachment process.Notched PV panels are secured to non-PVpanels with metal fasteners.

design briefs: Ford Island

This illustration shows how the notched BIPV standing-seam componentsoverlap the regular roofing panels.

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Junction box at ridge, viewed from below

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Junction box at ridge, viewed from above

Additional electrical junction boxes were required over potted terminals and raceways at the ridge, before theridge cap was installed.

Workers install short lapped roofing pans at BIPV module sections.

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The part of the roof containing BIPV spans a dock area, as shown in this illustration.

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DescriptionStaff in the Department of Energy’sWestern Area Power AdministrationSierra Nevada Region (SNR) have had twomain goals for SNR's photovoltaic (PV)program: (1) promote PV systems as arenewable energy resource, and (2) doso in a cost-effective manner. In supportof these goals, SNR has incorporatedPV panels into the roofs of buildings inElverta and Folsom, California. The build-ing-integrated systems will repay invest-ments in them by extending roof lives,reducing maintenance costs, generatingelectric power, and reducing the build-ings' cooling requirements.

In Phase I, a 40-kW building-integratedphotovoltaic system was installed at

SNR's Elverta Maintenance Facility. TheSacramento Municipal Utility District(SMUD) funded the PowerLight Corp.PowerGuard® system, while Westerncontributed funds equivalent to the costof replacing the facility roof. Funding wasalso provided by the Utility PhotovoltaicGroup (UPVG) through TEAM-UP, withsupport from the U.S. Department of Energy.

With a power capacity of 40 kW peak DCand an annual energy output of more

than 70,000 kWh/year, the PV systemshave significant environmental benefits.Phase I prevents the emission of 2,300 tons of carbon dioxide, 8.7 tonsof nitrogen oxides and 16.4 tons of sulfurdioxides; these emissions would be theresult if fossil fuels were burned togenerate the same amount of electricity.Because this system is designed to havea life expectancy of 20 years, the cumula-tive benefits for the environment aremany.

Special Design ConsiderationsPowerGuard PV tiles were used to reroof the building, saving on the cost of con-ventional roofing material. The patentedPowerGuard tiles incorporate high-effi-ciency polycrystalline silicon cells fromSolarex. Site conditions were favorablefor this sytem: 38° latitude; a dry, sunnyclimate throughout most of the year; andno shading. The system features horizon-tal tiles and tiles with an 8° southerly tilt

for greater annual energy production. In

addition to generating clean renewableenergy, the lightweight system providesR10 roof insulation for improved buildingcomfort and membrane protection forextended roof life. Installation took only7 days to complete once the building'sold roof was replaced with a new single-ply membrane roof.

PV System ConfigurationA 40-kW PowerGuard building-integratedPV system was installed at the ElvertaMaintenance Facility in Western's SierraNevada Region to function as both a roof and solar electric photovoltaic (PV) powerplant. Phase I modules were installed inparallel strings containing 56 modules perstring (7 series, 8 parallel).

design briefs: Western Area Power Administration 2

A view of the rooftop of the Elverta facility after the PV system installation.

A PowerLight rooftop PV system is installed on Western’s facility inElverta, California.

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PV Module Mounting and Attachment DetailsThe panels are designed to interlockusing a tongue-and-groove assembly.Panels with 3/8-in. concrete topping,instead of PV modules, are set amongthe PV panels to allow working accessthroughout the roof. Along the edgesof the PV array, a steel ribbon links the

modules together, in order to connecteverything structurally.

26 design briefs: Western Area Power Administration

The temperature curves show how the PV-integrated roof compares with various roofs without solar electricsystems. Roof-integrated PV with integral insulation reduces a building’s heat load as much as 23°C. Themeasurements were derived from sensors placed in representative roof specimens.

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Workers carry PV modules with attached foam backing in preparation for rooftop mounting. Smaller panels with concrete topping were alsoinstalled as a walking surface.

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DescriptionThis 38-kW BIPV system supplements thePhase I system. Both systems completelycover the Elverta roof and are the largestPV application of its kind in the UnitedStates. Phase II is totally funded andowned by Western. The PV systems utilizethin-film amorphous silicon technology.The DC output from the PV modules isconverted to 240 V AC by means of acustom-built 32-kW Trace inverter, andthen stepped up to 480 V, three-phaseAC by a 45-kVA transformer for directconnection to the building's servicepanel. Besides replacing grid power, thePowerlight system protects the roof

membrane, which extends its life. The roof system also provides R10 insulation toreduce cooling and heating loads, therebydecreasing energy consumption.

Special Design ConsiderationsThe flush roof design provides excellentinsulation as well as electricity, as shownin the graph comparing roof temperaturedata.

PV System ConfigurationThe Solarex modules were installed in254 parallel strings, with three Solarex modules in series per string. The modules

produce 43 watts each. The APS moduleswere installed in 22 parallel strings with12 modules in series per string. The APSmodules produce 22 watts each.

PV Module Mounting and Attachment DetailsSame as those for Phase I.

design briefs: Western Area Power Administration 2

The illustration shows how the layers in the roofs provide above-averageinsulation as well as a good base for the PowerGuard PV system.

RoofingMembrane

Solar ElectricPanel

Styrofoam® Insulation

Substrate Roof Deck 02527234m

Phase IILocation: Elverta, CaliforniaOwner: U.S. Department of Energy (DOE) Western Area Power AdministrationDate Completed: June 1998 Architect & Designer: DOE Western Area Power Administration, PowerLight Corporation

System Integrator: PowerLight CorporationStructural Engineers: DOE Western Area Power AdministrationElectrical Engineers: DOE Western Area Power AdministrationTradesmen Required: Electrical and building contractors Applicable Building Codes: Standard California building codes Applicable Electric Codes: National Electric CodePV Product: PowerGuard™ BIPV roof tilesSize (kWp): 38 kW DCProjected System Electrical Output: 67,500 kWh/yearGross PV Surface Area: 9,900 ft 2

PV Weight: 5 lb/ft 2

PV Cell Type: Thin-film amorphous siliconPV Efficiency: 4%-5%PV Module Manufacturer: Solarex (762 modules) and APS (264 modules)Inverter Number and Size: One 32-kW ACInverter Manufacturer and Model: Trace TechnologiesInterconnection: Utility-Grid-Connected

Phase I

Phase II

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28 design briefs: Photovoltaic Manufacturing Facility

Photovoltaic Manufacturing Facility Location: Fairfield, CaliforniaOwner: BP SolarDate Completed: 1993 Architect & Designer: Kiss Cathcart Anders, ArchitectsStructural Engineers: Ove Arup & Partners

Electrical Engineers: Ove Arup & PartnersTradesmen Required: Glaziers, electricians Applicable Building Codes: BOCA and California Title 24 Applicable Electric Codes: National Electric CodePV Product: Glass laminates as curtain wall spandrel, skylight, and awningSize: 9.5 kWpProjected System Electrical Output: 7.9 kWGross PV Surface Area: 1,975 ft2

PV Weight: 3 lb/ft 2

PV Cell Type: Amorphous siliconPV Efficiency: 5%PV Module Manufacturer: APSInverter Number and Size: 6 kWInverter Manufacturer: Omnion CorporationInterconnection: Utility-Grid-Connected

Views looking north (top) and south show how BIPV is integrated into both the facade and thecanopy that runs the length of the building.

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DescriptionCompleted in 1993, this 69,000-ft 2 manu-facturing facility houses a new generationof production lines tailored to thin-film

PV technology. The building also incorpo-rates into its design several applicationsof thin-film solar modules that are proto-types of BIPV products.

The heart of the project is a 22.5-ft-highBIPV glass cube containing the factory’scontrol center and visitor facilities. Thiscube is perched on the second floor, andhalf of it is outside of the manufacturingbuilding, emphasizing its status as anindependent element and a prototype

that demonstrates BIPV in a typical com-mercial building. The cube’s PV cladding,the solar entrance canopy, and the trans-lucent BIPV skylight provide more thanenough energy to power the controlcenter’s lighting and air-conditioning

systems.The production floor and warehousespace are housed in a tilted-up concreteshell with a steel intermediate structureand a timber roof. Glass blocks embeddedas large-scale "aggregate" in the outsidewalls provide a pattern of light in the inte-rior during the day and on the exterior atnight. Mechanical service elements arecontained in a low, steel-framed structureon the north side of the building. Theentry court is paved in a pattern of tintedconcrete and uplighting that representsan abstracted diagram of solar energygeneration.

Special Design ConsiderationsIn addition to providing a working productdevelopment test bed for BIPV systems,the project serves an educational functionfor public and private groups. Thelobby/reception area provides displayspace for products and research. A pat-tern cast into the paving in front of themain entry combines a sun path diagram

with a representation of the photovoltaiceffect at the atomic level. The controlroom/cube also serves an educational

design briefs: Photovoltaic Manufacturing Facility 2

Interior view shows how BIPV isused with vertical and slopedglazing.

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This office interior view demonstrates the quality of light transmittedby the approximately 5% translucent BIPV panel skylight.

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Sectional view indicates skylight configuration and curtain-wall facade.

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function; a raised platform allows groupsof visitors to view the control equipment,and beyond it, the production line.Computerized monitoring equipment dis-plays the status of the PV systems as wellas information regarding building HVAC

and lighting energy use, exterior ambientconditions, insolation, and other data.

Wherever possible, the PV systems aredesigned to do double duty in terms of energy management by reducing heatgain while providing power. The curtainwall and skylight are vented, eliminatingradiant heat gain from the modules andenhancing natural ventilation in the cube.The awning is designed to shade the rowof south-facing windows that open intothe production area and employeelounge. The cube curtain wall integratesPV modules with vision glass in astandard pressure plate curtain wallframing system, modified to be self-ventilating. The system is intended tobe economical and adaptable to newconstruction or retrofit.

PV System ConfigurationThe PV module is a nominal 2.5 ft x 5.0 ft,a-Si thin-film device rated at 50 Wp stabi-lized. The PV system contains 84 full-sizemodules mounted on the awning, 91 mod-ules installed in the curtain wall, and 8 ina skylight. The curtain wall modules areinstalled in custom sizes as required byarchitectural conditions. The system hasa total capacity of 7.9 kW; because of thevarying orientations of the modules, thepeak output is 5 kW. Despite the hot localclimate, the power consumed by the cubefor cooling and lighting never exceeds3.5 kW, producing a surplus of PV powerwhich is directed into the main buildinggrid.

PV Module Mounting and Attachment DetailsStandard PV modules are 31 in. x 61 in.but can be produced in custom sizes asrequired to fit the framing requirements of the curtain wall. One unique feature isthat the modules are glass-to glass lami-

nated products. The modules are installedwith an insulated inner liner, which formsa plenum for ventilation. Heat radiatedinto the curtain wall plenum is vented tothe outside by natural convection throughholes drilled in the horizontal mullions. In

some cases, the hollow vertical mullionsare used as ducts to direct the warm airupward.

The skylight panels are standard modulesthat transmit approximately 5% of thesunlight through the laser scribe lines.The PV modules are supplemented byclear glazing units to increase light trans-mission. Another unique feature of thisBIPV system is that the skylight is ventedto remove heat gain from the modules.

The awning panels are bolted through the

steel tube awning structure to aluminumchannels epoxied to the encapsulatingglass. This is the attachment used in typi-cal field-mounted arrays.

design briefs: Photovoltaic Manufacturing Facility 3

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34 design briefs: Yosemite Transit Shelter

Yosemite Transit Shelters

The transit shelter prototype makes use of both high-tech and low-tech materials, combining locally forested lumber with BIPV panels.

02527238m

Location: Yosemite National Park, CaliforniaOwner: U.S. Department of Interior, National Park ServiceDate Completed: Scheduled for system completion in 2001 Architect & Designer: Kiss + Cathcart, ArchitectsStructural Engineers: Ove Arup & Partners, Structural Engineers

Electrical Engineers: None; design overview provided by inverter manufacturerTradesmen Required: Standard Contractor/Carpenter and Electrician Applicable Building Codes: National Park Service, self-regulating Applicable Electrical Codes: National Park Service, self-regulatingPV Product: Amorphous silicon glass panelsSize: 560 Wp per transit shelterProjected System Electrical Output: 1.15 MWh/yrGross PV Surface Area: 112 ft2

PV Weight: 3.375 lb/ft 2

PV Cell Type: Amorphous siliconPV Efficiency: 6%PV Module Manufacturer: Energy Photovoltaics, Inc.Inverter Numbers and Size: 1 kWInverter Manufacturer: Advanced Energy SystemsInterconnection: Optional—Grid-Connected or Stand-Alone

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Description Yosemite National Park is one of the mosttreasured environments in the UnitedStates – and also the site of serious vehic-ular traffic congestion. The National ParkService is working to reduce traffic andpollution in Yosemite by expanding theshuttle bus service and introducing elec-tric shuttle buses. This necessitates aninfrastructure of combined weather shel-ters and information boards at the newshuttle stops.

Funded by DOE FEMP, Kiss + Cathcart,Architects, is under contract to NREL todesign a prototypical bus shelter incorpo-rating BIPV panels. The park will begininstalling the first of 19 new shuttle stopsin the summer of 2000. The shelters that

are near existing electrical lines will sendthe power they generate into the utilitygrid system serving Yosemite; the moreremote shelters will have battery storagefor self-sufficient night lighting.

Special Design ConsiderationsThe design mandate for this project is tobalance a sense of the rustic historicalbuilding style of the Yosemite Valley withthe frankly technological appearance of BIPV systems. The overall structure isa composite of heavy timber and steelplates that serves two purposes: accom-modating heavy snow loads with mini-mum structural bulk and projecting anappearance that is rustic from a distancebut clearly modern in a close-up view.The structural timbers (unmilled logsfrom locally harvested cedar) are splitin half, and the space between them isused for steel connections, wiring, andmounting signage. The BIPV roof struc-ture is made of a single log cut into eightseparate boards.

A shallow (10°) tilt was chosen for the PVroof. A latitude tilt of approximately 37°would provide the maximum annual out-put in an unobstructed site; however, ashallower angle is better suited to Yosemite because of the considerableshading that occurs at low sun angles inthe valleys, especially in winter. A steeperslope would also have made the shuttlestop much taller, significantly increasingstructural loading and demanding a heav-ier structure. This was determined to be

undesirable in terms of both appearanceand material use.

PV System ConfigurationFourteen semitransparent, 40-W thin-filmmodules make up the PV system for eachshelter. Power is fed to a single inverter.Some systems will be grid-connected andsome will be stand-alone with batteriesfor backup.

PV Module Mounting and Attachment DetailsThe PV roof of the shelter is not designedto be watertight like the roof of anenclosed building. Instead, it is designedto be waterproof so that water does notdrip through the roof in normal weather

conditions. Therefore, the PV modules areoverlapped (shingled) slightly along thecenter seam, and sheet metal gutters areinserted at the seam between the roughwood rafters and the modules.

design briefs: Yosemite Transit Shelter 3

Yosemite National Park

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38 design briefs: State University of New York, Albany

State University of New York, Albany

Looking southeastat the Center for EnvironmentalSciences andTechnology Management

Location: Albany, New YorkOwner: State University of New York, AlbanyDate Completed: Summer 1996 Architect: Cannon ArchitectsElectrical Engineer: Cannon Architects

Solar Consultant: Solar Design Associates, Inc.Tradesmen Required: Beacon Sales Corporation, roofing contractors Applicable building codes: New York State Building Code and ANSI Z97.1 Applicable electrical codes: National Electric CodePV product: Kawneer 1600 PowerWall™Size: 15 kWpProject System Electrical Output: 19,710 kWh / yr.Gross PV Surface Area: 1,500 ft2

PV Weight: 1.93 lb / ft 2

PV Cell Type: Polycrystalline siliconPV Cell Efficiency: 12%PV Module Manufacturer: Solarex Inverter Number and Size: AES 250 wattInverter Manufacturer and Model: Advanced Energy Systems Micro InverterInterconnection: Utility-Grid Connected

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40 design briefs: Navajo Nation Outdoor Solar Classroom

Navajo Nation Outdoor Solar Classroom

Each new BIPV structure at the Seba Dalkai School will serve as an open-air classroomsupported by timber columns in a concrete foundation.

Location: Seba Dalkai, Navajo Reservation, ArizonaOwner: Seba Dalkai Boarding SchoolScheduled Completion Date: Fall 1999 Architect: Kiss + Cathcart, ArchitectsElectrical Engineer: Energy Photovoltaics, Inc.

Solar Consultant: Kiss + Cathcart, ArchitectsTradesmen Required: Electricians, laborers Applicable Building Codes: Standard building codes Applicable Electrical Codes: National Electric CodePV Product: Energy Photovoltaics EPV-40 modulesSize: 4.0 kWpProjected System Electrical Output: 5,818 kWh/yrGross PV Surface Area: 625 ft 2

PV Weight: 3.75 lb/ft 2

PV Type: Amorphous siliconPV Efficiency: 6%PV Module Manufacturer: Energy Photovoltaics, Inc.Inverter Number and Size: Four 2.5 kW invertersInverter Manufacturer: Trace EngineeringInteronnection: Stand-Alone System

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DescriptionThe Seba Dalkai Boarding School, aBureau of Indian Affairs school on theNavajo Reservation in Arizona, is con-structing a new K-8 facility to be com-pleted in 2001. Funded by DOE FEMP, thisfacility will incorporate a BIPV systemcapable of producing approximately4.0 kW of electricity.

The school is currently housed in atraditional hogan and in a stone facilitybuilt in the 1930s. These will remain andbe juxtaposed with a new school facility.The photovoltaic component of thisproject will mediate between the old andthe new, and it will add a structure thatclearly expresses solar technology andBIPV principles. Funded by DOE FEMP,this structure will serve as an outdoorclassroom and as part of the school’sHVAC circulation system. It will also be ahands-on laboratory for educating peopleabout BIPV systems and training them insystem installation.

Special Design ConsiderationsThe installation is designed to minimizethe cost of the support structure whileincorporating sustainable constructionmaterials. Within an enforced simplicity,the design attempts to establish a con-nection with Navajo building traditions.

PV System ConfigurationThe design includes two 25-ft x 25-ft,open-sided, timber-framed structures.Each one supports 2.88 kW of semitrans-parent PV modules, and each oneincludes two Trace 2.5-kW inverters plusbatteries for three days’worth of energystorage. Each structure will function as anopen-air classroom.

PV Mounting and AttachmentDetailsThe PV modules are attached with alu-minum extrusions fixed with silicone tothe back of the glass (four per module).Each aluminum channel is 12 ft long. The

channels are supported on a grid of roughtimber beams, which in turn are sup-ported by timber columns on concretefoundations.

design briefs: Navajo Nation Outdoor Solar Classroom 4

The design attempts to establish a connection with Navajo building traditions.

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DescriptionIn this project, a regularly scheduled roof replacement was upgraded to the installa-tion of a building-integrated photovoltaicroof. The BIPV roof is installed on theWilliams Building in downtown Boston.The U.S. Coast Guard is the leading tenantof this 160,000-ft 2 building, which sits onRowe’s Wharf at 408 Atlantic Avenue, nearthe city’s financial district.

In addition to the new PV system for theroof, the building is also switching fromdistrict steam to on-site gas boilers. Two75-kW Teco-gen co-generation units arealso being added, as well as a high-efficiency chiller, more efficient lighting,and upgraded, more efficient motors.

Special Design ConsiderationsThe building is located on a wharf, so thedesign must take into account not onlythe water but also 140-mile-per-hour windconditions at the site.

After a site review, including a review of the wind conditions, the contractordecided to use a PowerLight RT photo-voltaic system. The RT system was chosenfor its cost-effectiveness when extremeroof penetrations are required (for exam-ple, with penthouses, skylights, and HVACframes).

PV System ConfigurationThis system produces 37 kWp DC and28 kW AC. Its 372 PV panels are con-nected in sets of 12. Each panel has a

maximum output of 100 watts.

PV Mounting and AttachmentDetailsA metal raceway, ballast, and anchoringsystem is used. It was also necessary toadd rigid insulation for thermal protection.

The PowerLight RT system is fastened tothe roof along its perimeter using epoxy-embedded anchors set into the concretedeck. These use pitch pans and a racewayfor moisture protection. The systemallows water to flow under thePowerGuard to existing roof drains. Itshould not be necessary to add newdrains.

A harness from the panels goes throughtwo conduits into attic space locatedabove the eighth floor. Part of the attic

needed additional metal decking.

design briefs: General Services Administration, Williams Building 4

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View of the new BIPV roof onthe Williams Building, during and after construction

Pavers are in foreground, PV array is in background onthe rooftop.

Wiring for the rooftop installationPaul King, DOE Boston Regional Office FEMPliaison, surveys the installation work.

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The plan for the roof of the Williams Building included a rooftop BIPV system consisting of 372 solar panels.

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Co-funded by the DOE FEMP Renewable Energy Program, this BIPV application illustrates how thetechnology can be introduced into complex roof spaces.

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Shading from other buildings is not a problem at thissite, which is in urban Boston.

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design briefs: Academy of Further Education 4

Academy of Further Education

The Academy of Further Education under construction in Herne, Germany

Location: Herne, North Rhine-Westphalia, GermanyOwner: EMC, Ministry of Interiors of North Rhine-Westphalia, City of HerneDate Completed: May 1999 Architect & Designer: Jourda et Perraudin Architects, HHS ArchitectsStructural Engineers: Schleich, Bergermann and Partner

Electrical Engineers: HL-TechnikTradesmen Required: Glaziers, electriciansPV Product: BIPV roof Size: 1 MWpProjected System Electrical Output: 750,000 kWh/yrGross PV Surface Area: 10,000 m 2

PV Weight: 130 kg per each 3.2 m 2 modulePV Cell Type: Polycrystalline and monocrystalline siliconPV Efficiency: 12.8% to 16%PV Module Manufacturer: Pilkington Solar International, CologneInverter Number and Size: 600, 1.5 kWInverter Manufacturer and Model: SMA, KasselInterconnection: Utility-Grid-Connected

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DescriptionAs part of the International ConstructionExhibition, Emscher Park, the site of a for-mer coal mine in Herne, Germany, is beingused for a new purpose. A comprehensiveurban development plan is providing thedistrict of Sodingen with a new center-piece: the Academy of Further Education,Ministry of Interior, North Rhine-Westphalia.

The large glass hall incorporates not onlythe Academy but also a hotel, library, andadministrative municipal offices. Theglass hall is multifunctional. It protectsthe interior from harsh weather and usessolar energy both actively and passivelyby producing heat as well as electricpower.

Special Design ConsiderationsApproximately 3,180 multifunctional roof and facade elements are the core of thesolar power plant. With a total area of 10,000 square meters, most of the roof and the southwest facade is covered byphotovoltaics, making this system thelargest building-integrated PV powerplant in the world. It produces approxi-mately 750,000 kWh of electric powerper year. This is enough to supply morethan 200 private residences. About200,000 kWh is used directly by theAcademy building, and the remaining550,000 kWh is fed into the public powergrid in Herne.

PV System ConfigurationThe Optisol photovoltaic elements wereproduced by Pilkington Solar at a site inGermany. The PV system consists of solarcells embedded between glass panes.Daylighting needs were taken intoaccount in designing the roof- and facade-integrated system. The PV modules haveareas of 2.5 to 3.2 square meters and anoutput of 192 to 416 peak watts each. Thismakes them larger and more powerfulthan most conventional solar modules.

Direct-current electricity is converted to230 V alternating current by means ofa modular inverter. This is made up of roughly 600 decentralized string invertersand allows optimal use of the incidentsolar radiation.

Mounting and AttachmentDetailsThe building-integrated photovoltaicpanels are set into aluminum mullionslike skylights. The rooftop panels arepositioned at an angle to capture as muchof the incident sunlight as possible.

46 design briefs: Academy of Further Education

An inside view of the Academy building as construction progressed

This photo shows how the PV panels are angled to capture the sunlightshining on the roof.

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Rooftop view shows placement of insulation and PV panels.

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48 design briefs: Discovery Science Cente

Discovery Science Center

Architect’s renderingof the Discovery Science Center Cubein Santa Ana,California

Location: Santa Ana, CaliforniaScheduled Completion Date: November 1999 Architect & Designer: Arquitectonica for the cube, Solar Design Associates for the PV systemStructural Engineers: Advanced Structures, Inc.Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians Applicable Building Codes: Building Administrators Code Administrators International (BOCA) Applicable Electrical Codes: National Electric CodePV Product: Thin-film photovoltaic systemSize: 20 kWpProjected System Electrical Output: 30,000 kWh/yrGross PV Surface Area: 4,334 ft 2

PV Weight: 3 lb/ ft 2

PV Cell Type: Thin-film technologyPV Efficiency (%): 5.1 %PV Module Manufacturer: BP Solarex Inverter Number and Size: 4Inverter Manufacturer and Model: Omnion 2400, Model 5015Interconnection: Utility Grid-Connected

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DescriptionThis solar electric system, located inSanta Ana, California, boasts one of theworld's largest building-integrated thin-film applications to date. The PV-coveredsurface of the cube is tilted at 50° formaximum visual impact and optimal solarharvest. BP Solarex's Millennia modulescover the entire 4,334-ft 2 top of the cubeThe thin-film modules are treated as an

architectural glazing element, replacingwhat would have been a glass canopy.They produce up to 20 kW of DC electricityat mid-day and 30,000 kWh of electricalenergy per year, which is enough to runfour typical homes.

The solar energy system is connectedto the Discovery Science Center's mainutility line. When the solar system pro-duces energy, it feeds the energy to the

Science Center, displacing conventionalutility power. When the solar systemproduces more electricity than theScience Center needs, the excess elec-tricity is "exported" to the utility, therebyeffectively spinning the electric meter

backwards.

design briefs: Discovery Science Center 4

The view from inside the cube

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50 design briefs: Solar Sunflowers

Solar Sunflowers

These Solar Sunflowerstrack the sun to produceelectricity.

Location: Napa, CaliforniaDate Completed: N/A Architect & Designer: Solar Design Associates, Inc.Structural Engineers: Solar Design Associates, Inc.Electrical Engineers: Solar Design Associates, Inc.

Tradesmen Required: Electricians Applicable Building Codes: Building Officials Code Administrators International (BOCA) Applicable Electrical Codes: National Electric CodePV Product: BP Solarex Size: 36,000 WpProjected System Electrical Output: N/AGross PV Surface Area: 3,456 ft 2

PV Weight: 3.4 lb/ ft 2

PV Cell Type: PolycrystallinePV Efficiency: 11.1%PV Module Manufacturer: BP Solarex Inverter Number and Size: 6Inverter Manufacturer and Model: Omnion Series 2400, Model 6018Interconnection: Utility-Grid-Connected

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DescriptionNestled atop a hillside in NorthernCalifornia, 36 Solar Electric Sunflowersrepresent an elegant combination of artand technology. The clients requested anunconventional and artistic installation.They got just that.

Just like a sunflower, the Solar ElectricSunflowers look and act like nature's ownvariety. Making use of a two-axis trackingsystem, the sunflowers wake up to followthe sun's path throughout the day,enabling the system to produce enough

energy for eight to ten homes.

design briefs: Solar Sunflowers

Solar electric sunflowers resemble nature’s own.

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DescriptionThis Dutch-American design collaborationis intended to develop a new standard inEurope for moderately priced housingwith integrated solar electric systems. Thefirst phase consists of 14 row-house units,each with its own grid-connected BIPVarray. As part of a highly ordered "newtown" development adjacent to the citycenter of Ijsselstein, these units conformto strict space and budget guidelinesas well as to advanced standards of PVintegration.

The overall design is a composition of brick volumes and two-level, wood-framed sunrooms. The latter are partiallyclad in opaque and translucent PV units,and they are raised and staggered tomaximize solar exposure. The sunroomvolumes are wood-paneled on the sidesfacing north.

The Netherlands is home to some of themost advanced PV systems in the world.However, before this project began, littlework had been done on integrating solararrays into the prevailing Dutch architec-tural idiom of abstract cubic forms. TheIjsselstein row houses demonstrate howphotovoltaics can be a fully participatingelement in the design, rather than justan applied system. Amorphous siliconmodules in particular are generating very

positive responses among many Dutcharchitects, who perceive them as lookingmuch more like an architectural materialthan polycrystalline panels do.

Special Design ConsiderationsIn marked contrast to the United States,The Netherlands favors residential designthat is largely modern and rational in

character. The ubiquitous pitched roofsof North American houses (which provideconvenient mounting surfaces for PVarrays) were considered aestheticallyundesirable at Ijsselstein. However, athigher latitudes with low sun angles, ver-tically mounted BIPV panels can generatepower at output levels competitive withthose of optimally angled panels. Thedesign takes advantage of this by usingstandard-sized units as glazing andexterior enclosure combined in a simplewooden frame wall.

Extensive computer modeling studieswere done to ensure that the complex massing of the row houses works to pro-vide maximum solar exposure for eachunit’s array and minimum shadowing of BIPV surfaces by adjacent units.

Given that BIPV glass is a major claddingcomponent for the sunroom elements,excessive interior heat loss or gain wasa significant design consideration. Theadjacent stair serves as a convection

chimney that actually uses the heatedair produced in the sunrooms to draw aircurrents through the entire row house,cooling it in warm weather. Cold weatherconditions are addressed simply byproviding a suitable layer of insulationbetween the cladding and the interiorfinish.

PV System ConfigurationA 1.6-kW, grid-connected BIPV system ispart of each row house. Each system willbe individually metered, and there is nobattery storage.

PV Module Mounting and Attachment DetailsStandard PV modules are set into a woodframing system, which can be either site-built or prefabricated. The opaque unitsare set as typical single glazing, usingminimum-profile glazing stops and caulk.The translucent panels are incorporatedinto double-glazed window units. Thehorizontal members of the wood framehave an absolute minimum exposeddepth to prevent shadowing. The verticalmembers, which are not as likely to inter-fere with solar exposure, have a raisedprofile.

design briefs: Ijsselstein Row Houses 5

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Sample floorplans for row-house units

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54 design briefs: Denver Federal Courthouse

Denver Federal Courthouse

The U.S. Court House expansion in Denver will be a showcase for sustainable building design.

Location: Denver, ColoradoOwner: U.S. General Services AdministrationDate Completed: Scheduled for completion in 2002 Architect & Designer: Anderson Mason Dale (Architects); Hellmuth, Obata, & Kassabaum, St. Louis

(Designers); Architectural Energy Corporation (Energy Consultants)System Integration: Altair Energy (PV Consultant)Structural Engineers: Martin/Martin, Inc.Electrical Engineers: The RMH Group, Inc.Tradesman Required: Building tradesmen/glaziers Applicable Building Codes: Uniform Building Code (1997) Applicable Electric Codes: National Electric Code (1999)PV Product: Custom-sized BIPV glass laminateSize: 15 kWp (roof); 3.4 kWp (skylight)Projected System Electrical Output: 20,150 kWh per year (roof); 4,700 kWh per year (skylight)Gross PV Surface Area: 172 m2 (roof); 59 m 2 (skylight)PV Module Weight: 4,661 kg (roof); 2,749 kg (skylight)PV Cell Type: Single- or polycrystalline siliconPV Efficiency: 10% or greaterPV Module Manufacturer: Pilkington SolarInverter Number & Size: One 20-kW and one 3.4-kW inverterSuggested Inverter Manufacturers: Trace Technologies, Trace Engineering, OmnionInterconnection: Utility-Grid-Connected

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DescriptionThe United States Courthouse Expansionin Denver, Colorado, consists of 17 newcourtrooms and associated supportspaces for an additional 383,000 ft 2(35,600 m 2 ). The U.S. General ServicesAdministration (GSA) approached theexpansion of this Federal Courthouse indowntown Denver as a showcase buildingfor sustainable design. One of the GSA’sproject goals was to "use the latest avail-

able proven technologies for environmen-tally sensitive design, construction, andoperation. It should set a standard and bea model of sustainable design." Anothergoal was to create a building that wouldremain usable for its 100-year lifespan.

The design projects an image of respectand reflects the city’s rich architecturalheritage. The 11-story structure housessix floors of district courts, two floors of magistrate courts, offices for the UnitedStates Marshal, a jury assembly area,

and a special proceedings courtroom.Anderson Mason Dale P.C. is the architectof record, and HOK served as the designarchitect.

Recalling a traditional town squarecourthouse, the two-story pavilion is anarrangement of two geometric formsunder a large horizontal roof. It is thefrontispiece of the entire composition.An open peristyle colonnade supportsthe roof and transparently encloses the

entrance lobby and the drum-shapedsecured lobby. As a series of verticallyoriented rectangular planes, the

courthouse tower caps the structurewith an open framework and a floatinghorizontal roof of photovoltaic panels.

With technical assistance provided byFEMP, the project’s sustainable designconsultant, Architectural Energy Corpora-tion of Boulder, Colorado, and the designteam developed the building’s overallsustainable design strategies. The build-ing achieves a high level of energy effi-ciency through a combination of

strategies that seek first to reduce build-ing energy loads as low as possible andthen to satisfy the remaining reduced

design briefs: Denver Federal Courthouse 5

This chart summarizes the BIPV system design:Component Orientation Effective Size Annual

Area (m2 ) (kW) kWh

Roof area Horizontal 173.4 13.9 23,300

Lobby skylight Horizontal 63.6 4.4 7,400

Photovoltaics will be integrated into the top roof louver of the tower and into a skylight above the lobby rotunda.

0 2 5 2 7 2 7 8 m

Standard SkylightGlazing

InsulatedPhotovoltaicGlass

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loads through state-of-the-art, high-efficiency mechanical and electrical sys-tems and renewable energy sources. Theunique attributes of the Denver climate,sunny skies and low humidity, are usedthroughout the design to minimize energy

consumption. The resulting building isa visible expression of sustainabilitythrough features that work together inan integrated energy-efficient system.

The improved building envelope allowssubstantial reductions in energy use forlighting, ventilation, and cooling. Thesereductions, along with the energy gener-ated from the BIPV system, will make theannual operating energy costs of the newcourthouse 43% lower than those of abuilding designed according to Depart-ment of Energy standards for energyefficiency (10 CFR Part 436, which isbased on ASHRAE 90.1-1989).

Energy savings were calculated by con-structing a simulation model of the build-ing that meets the minimum requirementsof the Federal Energy Standard (10 CFRPart 435). This minimally compliant build-ing (the base building) was the baselinefrom which energy savings were calcu-lated. A comparison of the simulatedannual energy costs for the base buildingand the proposed design is shown below.

Local materials, such as precast concreteand native stone, have been incorporatedinto the exterior cladding system. Thebuilding will have a steel frame with recy-cled material content. Most of the flooringmaterials in the building are made fromrecycled or native sources, includingnative stone, cork, or recycled plastics.Low-impact landscaping is used to mini-mize water use, reduce the "urban heatisland" effect, and provide an attractiveoutdoor space. Low-flow lavatory faucetsand water closets will be used throughoutto minimize water use. All interior finishmaterials were carefully selected on thebasis of their impacts on the environmentand occupants.

The building is crowned by a series of glazing-integrated PV modules incorpo-rated into the top horizontal roof louver of the tower and the skylight element abovethe cylindrical volume of the secure lobbyrotunda. This bold architectural statement

expresses both energy efficiency andadaptation to climate. The glazing-integrated PV array at the top horizontalroof louver of the tower is composed of crystalline cells covering approximately87% of the visible glazing area. This is

intended to be a highly visible element of the building’s architecture, recognizablefrom many places around the city.

The cylindrical volume of the secure lobbyrotunda culminates in an insulated BIPVglass skylight using crystalline cells cover-ing approximately 60% of the visible glaz-ing area; it provides necessary shadingwhile generating power for the buildingand making a statement about alternativeenergy sources. Perimeter skylightsaround the outside of the rotunda arelaminated glass. Setting the tone forother special places within the building,a perforated metal scrim ceiling diffusesthis light.

The BIPV panels provide electricity duringdaylight hours, reducing the building’speak electricity requirements. Direct cur-rent from the BIPV system is fed into thebuilding’s electrical system via a DC to ACpower-conditioning unit. Since the systemis utility-interconnected, battery storageis not necessary. Estimated total energyproduction from the two systems isapproximately 25,000 kWh per year, orabout 2% of the building’s total annualelectrical consumption.

The new U.S. Federal Courthouse expan-sion lends an optimistic, forward-lookingimage to the City of Denver while makinga strong case for sustainable design.Inside the courthouse, the design willproject a bright, airy appearance. "Green"design features also improve the workenvironment, which can lead to increasesin employee productivity and satisfaction.

By investing in improved materials andsystems, and using an integrated, envi-ronmentally conscious design approach,the GSA will reduce environmentalimpacts as well as long-term operatingcosts. Because the courthouse expansionhas been designated a "demonstrationproject" by GSA, it will be used to influ-ence future courthouse design projects.

Special Design ConsiderationsThe basic laminated BIPV glazing panelsare a compilation of square polycrystalinecells measuring 125 mm x125 mm. Themanufacturing process varies the densityand coverage of these cells within theBIPV panel to accommodate the designintent. This ability to custom-design indi-vidual BIPV panels allowed the designteam to specify skylight panels to be morelight transmissive, thereby providingample illumination of the lobby rotunda,and to design the roof louver panels withgreater opacity, thereby providingincreased power capabilities.

The laminated BIPV glazing panel of theskylights allows the phototvoltaic systemto be responsive to indoor safety and

security requirements. Condensation con-cerns also required that the skylight’sBIPV panels be integrated into an insu-lated glazing element.

In addition, the inside glass pane is lami-nated with a milk-white, PVB (polyvinylbutyral) inner layer to diffuse direct sun-light and obscure the less visually appeal-ing side of the crystalline cells from view.

PV System ConfigurationA one-line electrical schematic is given

for the two photovoltaic systems. Thephotovoltaic modules are wired in seriesand parallel to meet the voltage and cur-rent input requirements of the powerconditioning unit (PCU). To simplify thewiring between the PV array and the PCU,combiners are installed near the array.The array combiners include reversecurrent protection, surge protection,and series string fusing, and they providea convenient place for testing andtroubleshooting the PV array.

DC and AC disconnects enable properdisconnection and protection for the PCU.Depending on whether the output of thePCU is compatible with utility voltage andgrounding requirements, an external (tothe PCU) isolation transformer may beneeded. A utility-required relay mecha-nism provides over- and under-frequencyprotection and over- and under-voltageprotection. The utility disconnect is aredundant measure required by the utilityto ensure that the PV system will not

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backfeed utility lines that are not meantto be energized. The PCU has an anti-islanding feature that is the first line of defense against undesired backfeedonto the utility grid. The point of intercon-nection can be made in any electrical

distribution panelboard with the propervoltage and current ratings.

Because the BIPV arrays are located indifferent places on the building, eacharray will be equipped with its own dataacquisition system. The data acquisitionsystems will measure and record fourparameters that can be used to scrutinizethe performance of the BIPV systems.These parameters are the four requiredby the Utility Photovoltaic Group (UPVG)for its monitoring and rating program.This may also make the PV systemseligible for cost-sharing with UPVG. Thefollowing measurements and sensorswill be employed:

(1) Plane-of-array global solar irradiance(W/m2 ) will be measured with a Licorpyranometer mounted on the array.

(2) Wind speed (m/s) will measured withan NRG systems cup anemometermounted near the array.

(3) Ambient temperature (°C) will bemeasured with a thermistor insidea radiation shield mounted near thearray.

(4) PV system AC power/energy output(kW/kWh) will be measured with astandard accumulating energy meterwith a special pulse output device.This device will be located near thePCU.

The data from the two data acquisitionsystems will go to a central computer viastandard telephone wire. The computerwill probably be in a busy area, such asthe special proceedings lobby, to helpeducate the general public about BIPVsystems. The computer will have custom-designed software for displaying the datain a "cockpit" format (i.e., with graphicelements such as dials and strip charts).Both real-time and archived data will be

available on this display, along witheducational screens.

PV Module Mounting and Attachment DetailsThe glazing-integrated PV modules will

be shipped to the site individually withterminals for making electrical connec-tions. Because the skylight installer willmount the modules into the mullions andmake the electrical connections, the elec-trical connections must be very simple.Electrical terminals are located on thepanel edges so they are concealed bythe mullion system. Traditional moduleshave a junction box mounted on the back.Special plug-and-socket connectors willenable easy one-wire connections to bemade between adjacent modules. The

mullions will be constructed so that indi-vidual modules may be removed f