ORL NO. 154 DOE/JPL 955893DRO NO. MA-7 DISTRIBUTION CATEGORY UC-63

Irrtegrated ResidentialPhotovoltaic ArrayDevelopment

QUARTERLY REPORT NO. 1

PREPARED UNDER JPL CONTRACT 955893REPORT DATE: APRIL 10, 1981PREPARED BY: G.C. ROYAL, III

The JPL Low-Cost Solar Array Project is sponsored by the U.S.Department of Energy and forms part of the Solar PhotovoltaicConversion Program to initiate a major effort toward the develop.meet of low-cost solar arrays. This work was performed for theJet Propulsion Laboratory, California institute of Technology byagreement between NASA and DOE.

AIA Research Corporation

1735 New York Avenue, N.W.

Washington D.C. 20006

This report was prepared as an account of work sponsored by the United StatesGovernment Neither the United States nor the United Steles Department ofEnergy, nor any of their employees, nor any of their contractors, subcontrac-tors, or their employees, makes any warranty, express or implied, or assumesany legal liability or responsibility for the accuracy, completeness or usefulnessof any information, apparatus, proeuct or process disclosed, or represents thatits use would not infringe privately owned-rights.

ii

ABSTRACT

This first quarterly report on a contract to develop an optimal inte-

grated residential photovoltaic array describes sixteen conceptual

designs produced by eight teams. Each design concept was evaluated by an

industry advisory panel using a comprehensive set of technical, economic

and institutional critaria. Key electrical and mechanical concerns that

affect further array sub-system development are also discussed.

Three integrated array design concepts were selected by the advisury

panel for further optimization and development. From these concepts a

single one will be selected for detailed analysis and prototype fabrication.

The three conccpts selected are the following:

1) An array of frameless panels/modules sealed in a "T" shaped

zipperlocking neoprene gasket grid pressure fitted into an

extruded aluminum channel grid fastened across the rafters.

2) An array of frameless modules pressure fitted in a series of

zipperlocking EPDM rubber extrusions adhesively bonded to

the roof. Series string voltage is developed using a set of

integral tongue connectors and positioning blocks.

3) An array of frameless modules sealed by a silicone adhesive

in a prefabricated grid of rigid tape and sheet metal attached

to the roof.

i i i

TABLE OF CONTENTS

SECTION PAGE

1 Summary . . . . . . . . . . . . . . . . . . . . . . . . 1-1

2 Introduction . . . . . . . . . . . . . . . . . . . . . 2-1

3 Technical Discussion . . . . . . . . . . . . . . . . . 3-1

3.1 Evaluation Criteria

3.2 Description of Concepts Considered

3.3 Concept Evaluation

3.4 Concept Selection

4 Concl,isi ons and Rt :!3nenda* i cns . . . . . . . . . . . . 4.1

LIST OF TABLES

TABLE NUMBER PAGE

Table 1. Tabular Summary of Integrated ResidentialPV Array Design Concepts . . . . . . . . . . . . 3-10

LIST OF FIGURES

FIGURE NUMBER PAGE

2-1 Design Team, Workshop Lectures, AdvisoryPanel . . . . . . . . . . . . . . . . . . . . . 2-3

2-2 Project Activity Diagram . . . . . . . . . . 2-43-1 Design Concept 1 Electrical Characteristics . . . 3-123-2 Design Concept 1 Mechanical Characteristics . . . 3-133-3 Design Concept 2 Electric<l Characteristics 3-1"3-4 Design Concept 2 Mechanical Characteristics 3-15

3-5 Design Concept 3 Electrical Characteristics . . . 3-16

3-6 Design Concept 3 Mechanical Characteristics . . . 3-17

3-7 Design Concept 4 Electrical Characteristics . . . 3-18

3-8 Design Concept 4 Mechanical Characteristics . . . 3-19

3-9 Design Concept 5 Electrical Characteristics . . . 3-20

.)-10 Design Concept 5 Mechanical Characteristics . . . 3-21

3-11 Design Concept 6 Electrical Char cteristics . . . 3-22

3-12 Design Concept 6 Mechanical Characteristics . . . 3-23

3-13 Design Concept 7 Electrical Characteristics . . . 3-24

3-14 Design Concept 7 Mechanical Characteristics . . . 3-25

3-15 Design Cuncept 8 Electrical Characteristics . . . 3-263-16 Design Concept 8 Electrical Characteristics . . . 3-27

iv

LIST OF FIGURES (CONT'D)

FIGURE NUMBER PAGE

3-17 Design Concept 9 Electrical Characteristics . . . 3-283-18 Design Concept 9 Mechanical Characteristics . . . 3-293-19 Design Conce p t 10 Electrica l, Characteristics . . . 3-303-20 Design Concept 10 Mechanical Characteristics . . . 3-313-21 Design Concept 11 Electrical Characteristics . . . 3-323-22 Design Concept 11 Mechanical Characteristics . . . 3-333-23 Design Concept 12 Electrical Characteristics . . . 3-343-24 Design Concept 12 Mechanical Characteristics . . . 3-353-25 Design Concept 13 Electrical Characteristics . . . 3-363-26 Design Concept 13 Mechanical Characteristics . . . 3-373-27 Design Concept 14 Electrical Characteristics . . . 3-383-28 Design Concept 14 Mechanical Characteristics . . . 3-393-29 Design Concept 15 Electrical Characteristics . . . 3-403-30 Design Concept 15 Mechanical Characteristics . . . 3-413-31 Design Concept 16 Electrical Characteristics . . . 3-423-32 Design Concept 16 Mechanical Characteristics . . . 3-43

g

v

iSECTION 1

SUMMARY

This report discusses the first of three tasks to dofine an integrated

residential photovoltaic array. An optimum array configuration will satisfy

the needs of the earliest and largest market and provide electricity for the

least life cycle cost. This study emphasizes a systems approach to design

optimization that considers detailed electrical, mechanical, economic and

institutional factors. Further emphasis is the minimization of cost drivers

for these factors at several levels of annual production.

The study began with the competitive selection of 8 teams to produce a

set of design concepts. A workshop was conducted to review the current

technology base for residential photovoltaic systems. Workshop materials

referenced the following module/array topics: circuit design and perfor-

mance; wiring; mounting; installation, reliability and maintenance; codes

and standards; roof construction; and life cycle cost. These materials

were drawn from previous system definition and array requirements and 12

prototype designs for which detailed array and system analyses have been

performed.

The teams develop'd a total of 16 design concepts over a nine-week

period. Each concept was evaluated by an industry advisory panel convened

by the AIA/RC on the basis of the following criteria categories: market

penetration; fabrication requirements; design and specification requirements;

installation requirements; operation requirements; and maintenance require-

ments. Three design concepts selected for further development by the

advisory panel follow:

1) an array of frameless modules sealed in a zipperlocking neoprene

gasket grid in a grid of aluminum channels fastened across the

rafters;

2) an array of frameless modules sealed in a zipperlocking EPDM

extrusion adhesively bonded to the roof; and,

3) an array of frameless modules sealed by a silicune adhesive in

a prefabricated grid of rigid tape and sheet metal attached to

the roof.

1-1

This report summarizes the assumptions, rationale and methodology used

in the selection of the design concepts. Further concerns to be addressed in

subsequent study activities are also discussed.

1-2

SECTION 2

INTRODUCTION

The objective of this study is to develop optimal roof mounted arrays

for residences that provide energy for the least life cycle cost. Develop-

ment of an optimal array will follow an integrated systems approach that

considers detailea electrical, mechanical and environmental requirements,

as well as such regional variations as codes, construction practices and

local costs. The resulting array design will be fabricated in a prototype

partial roof/array model to identify additional roof array interface

concerns in prcduction, manufacturing, instailation or maintenance. Pro-

gram activity is organized into the three tasks listed below.

Task 1 - Alternative Design Concept Development

Task 2 - Preferred Design Concept Optimization

Task 3 - Prototype Roof/Array Section Fabrication

In Task 1 three (3) generic integrated photovoltaic ar:ay design

concepts are selected from a number of alternative concepts for residential

applications. This effort began with a solicitation to over 200 architects,

engineers, homebuilders and designers that asked for a statement of their

caoability to develop design concepts tc satisfy technical, economic and

institutional concerns. An industry advisory panel was convened by the

AIA/RC to select the most capable ,seams to develop a set of design

alternatives.

A workshop held at the AIA/RC for the design teams was used to esta-

blish a uniform starting point for the nine week concept design period.

The workshop was organized into three sessions. First an overview of

program activities and research results was presented. Next, project

activities and concept documentation requirements were reviewed. Then a

series of technical presentations were given for the following topics:

system design; module design; wiring and connector design; safety stan-

dards; and residential roof construction.

At the end of the concept design period, a presentation was given by

each of the eight design teams tc the advisory panel. The following

characteristics were reviewed in the presentation for each of the 16 con-

cepts developed: appropriateness for earliest and largest market

2-1

penetration; fabrication requirements; designed array output, modularity

and specification; array circuit design, wiring and module connection;

panel/module attachment; installation requirements; operation and

maintenance requirements; and, costs. Three concepts were selected b the

advisory panel for further development, prior to selection of a preferred

design for Task 2.

Design teams, workshop participants, and advisory panel members are

identified in Figure (2-1).

Based on the results of Task 1, one design concept will be selected

for further analysis and development under Task 2. Detailed production

design development and engineerinq trade-off studies will be performed

to further optimize the design for minimum life-cycle cost for the

installed array. Based on this detailed information, refined life-cycle

cost estimates will be generated for annual module production levels of

10000, 50000, and 500000 m2 . A se' or drawings and specifications will be

prepared to permit fabrication, installation and operation of the array

design by a third party. In addition, a full-scale prototype section/array

roof will be defined and a fabrication cost estimate prepared.

The Task 3 activity will include the fabrication on a full-scare

representative prototype section of the selected residential photovo'ta'c

array complete with electrical and mechanical interconnertors and array/

roof interface hardware. While this prototype section r;eed not be

electrically operational, it will serve as a useful model to identify

additional fabrication, installation, maintenance and other concerns.

A block diagram of program activities is shown in F i g ure (2-2). As of

this reporting date, all effort has been completed under Task 1 with the

exception of further development of the three selected conceots. This

report describes the results of the activities completed.

2-2

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2-4

SECTION 3

TECHNICAL DISCUSSION

This discussion summarizes key elements of the criteria, methodology

and rationale for selection of three design concepts from those considered.

The first section is a discussion of the assumptions and evaluation

criteria used in concept selection. The next section is a description of

each design considered. Subsequently, evaluation methodology is described

and major concerns for each concept are identified. Then, the rationale

and justification for selection of three concepts is pr,:sented.

she classification of mounting types in this study is based on a

performance approach. This approach distinguishes between mounting types

based on the method used to satisfy two roof functions: weather protection

and structural stability. This classification does not consider height

differences between array surface and roof, or material replacement.

Integral-mounted arrays provide ooth permanent and tempo rary weather

protection. Replacement support for lateral roof loads is required.

Modular array-edge support is required.

Direct-mounted arrays provide only permanent weather protection.

Replacement s upport for lateral roof loads is not required. Modular array-

edge support may not be required.

Standoff/Rack-mounted arrays do not provide weather protection.

Replacement support for lateral roof l oads is not required. Modular array-

edge support is required.

3-1

3.1 EVALUATION CRITERIA

The spectrum of technical, economic and institutiona' issues that affect

the fabrication, installation and operation of a residential photovoltaic

array have been grouped into six categories of evaluation criteria. Evalua-

tion objectives are the minimization of cost drivers associated with each

category. A partial listing of criteria follows the list of categories

below.

• Market Penetration

• Fabrication

' • Design and Specification

• Installation

9 Operation

• Maintenance

MARKET PENETRATION

The focus of this category is minimization of cost drivers for earliest

and largest market penetration. The characteristics of the maturing market as

well as the mature market are expected to establish a basis for the inter-

relationsh = p of fabrication, installation, residential construction,

operations and maintenance.

• The concept must satisfy the largest middle-income mass market.

• The concept must serve a variety of housing sizes, types, and

roof shapes.

• The concept must allow flexibility of selection by both large

and small volume builders.

9 The concept must allow flexibility in installation timing.• The concept must fit within the typical product delivery and

service chain of the homebuilding industry.

Fabrication

The focus of this category is an optimization of pe.sonnel, material

and equipment requirements from component delivery through shipment of the

assembly. That optimization should consider both number and type of person-

nel, material and equipment throughout the assembly sequence.

• The concept must optimize the mixture of factory and field labor

for array assembly.

3-2

• The concept must minimize the requirements for component inven-

tory.

• The concept must minimize the cost for shipping and handling yE

retain acceptable durability.

Design and Specification

The focus of this category is minimization of project-specific design

engineering. Elements considered include the ability to use equivalent

products, as well as the standardization of code approval, labor coordina-

tion, and engineering documentation.

• The concept must use the design engineering ca pability normally

employed by the builder or contractor.

• The concept must minimize field inspection and approval require-

ments of local building and zoning codes, the National Electrical

Code (NEC), fire codes and insurance warrants.

• The concept must allow use of equivalent materials and products

in standard construction practice.

• The concept must allow flexibility in labor and schedule

coordination that meets standard practice conditions.

• The concept's documentation must follow standard practice for

reliability, performance and cost estimates.

Installation

The focus of this category is minimization of installation time and cost.

Key concerns include array durability during site delivery and storage,

sequence of installation, required tools, equipment, labor and supervision.

An additional concern is minimization of field requirements for field

qualification and acceptance of the installed array.

• The concept must have little impact on the normal structural

and environmental exposure of the building.

• The concept must be compatible with standard construction

practices, tools and equipment.

• The concept must minimize field approval of electrical

connections, field cabling and grounding.

• The concept must minimize safety risk during installation.

• The concept must optimize handling and installation durability.

3-3

3-a

• The concept must optimize mechanical attachment and electricalconnection requirements.

Operation

The focus of this category is the optimization of reliable output

performance to match the requirements for system interface consistent with

standard safety conditions.

• The concept array must generate electricity within an acceptable

output range for size and temperature conditions.

• The concept array output must satisfy balance of system inter-

face requirements such as input voltage.

• The concept must minimize grounding concerns and requirements.

• The concept must address appropriate power and dimensional

modularity concerns.

• The concept must satisfy lifetime reliability and durability

conditions at an acceptable cost.

Maintenance

The focus of this category is the optimization of field maintenance,

repair and replacement consistent with least initial costs.

The concept must minimize the requirements for identification,

removal and replacement of failed parts consistent with reliability

and durability conditions.

• The concept must not interfere with normal building maintenance

and repair.

• The concept must minimize added life safety and building risks.

3.2 DESCRIPTION OF CONCEPTS CONSIDERED

Design concepts were developed by eight design teams for each of four mounting

strategies. In certain cases, the concepts were appropriate for more than one

mov,iting type. The following discussion summarizes key elements of concepts

developed for each of the mounting strategies. A tabular summary of system

descriptions is listed in Table ( 11. Condensed drawings of each concept

follow and appear as Figures 3-21 through 3-33.

Integral Mounting Concepts

Sample 1. Eighteen (18) unframed panels/modules are pressure fitted in a "T"

shaped neoprene gasket grid and sealed by a ziplocking strip. The

gasket grid is pressure fitted into an aluminum channel extrusion

grid fastened across the rafters. Array voltage is developed

along the roof height using a series string of two (2) panels/

modules. Array current is developed along the roof length using

nine (9) panel/module pairs attached to busbars at the top and

bottom of the array. Array termination is near the gutter along

the roof rake.

Sample 2. Ten (10) panel frames each made from two extruded aluminum carriage

pieces joined by lateral angles are bolted along the rafters. Each

of the nine (9) modules pressure fitted in a panel overlaps the

lower one and is held in place by a lap bar. The modules are

wired in series by commercially available 'quick connectors' with

return branch conductors attached to the rafters. Array voltage

is developed along the roof height from two (2) adjacent panels

wired in series through a junction box for each panel pair. Array

current is developed along the roof length from the five (5) panel-

pair junction boxes wired in parallel within the attic near the

ridge using redundant armored bus cable conductors.

Sample 3. Eighty (80) frameless modules are sealed using a silicone adhesive

to a prefabricated grid of rigid tape and metal channels bolted

across rafters. Array voltage is developed along the roof length

using a series string of 20 modules. Array current is developed

along the roof height using 4 parallel-wired module rows.

i

3-5

Integral Mounting Concepts (Cont'd)

Sample 4. Forty (40) gasketed modules are sealed in a set of prewired mounting

channels nailed along the length of the rafters. Array voltage is

developed along the length of the roof using a series string of 20

modules. Array current is developed along the height of the roof

using two (2) parallel-wired module rows.

Sample 5. Twenty-four (24) unframed modules are pressure fitted between a

series of extruded aluminum batten strips and plywood support strips

mounted along the rafters. Waterproof seal is provided by butyl

glazing tape at the top and sides of the modules. Array voltage

is developed along the roof length using three (3) modules wired in

series. Array current is developed along the roof height from

eight (8) branch circuits installed in three (3) rows. The bottom

row contains two (2) branch circuits while each of the two upper

rows contain three (3) branch circuits. Array termination occurs

in the power conditioning eyiupment room beneath the array.

Direct Mounting Concepts

Sample 6. Fifty-six (56) unframed modules are pressure fitted in a grid of

thermoplastic "T" and "I" shaped glazing gaskets fastened to the

roof. The "I" shaped sections have been coextruded with embedded

busbars for parallel module wiring. Each module rests on a ribbed

plastic backing sheet. Array voltage is developed along the roof

length from a seven (7) module series string wired through junction

boxes located in the attic. Array current is develo ped along the

roof height from eight (8) modules wired in parallel through the

integral busbars within the thermoplastic grid. Array termination

occurs through the ridge vent in the attic.

Sample 7. Eighty (80) frameless modules are sealed by a silicone adhesive

in a prefabricated grid of rigid tape and sheet metal attached to

the roof. Array voltage is developed along the roof length using

a series string of twenty (20) modules. Array current is developed

along the roof height using four (4) parallel-wired rows.

3-6

Direct Mounting Concepts (Cont'd)

Sample 9. Forty (40) gasketed modules are sealed in a set of prewired mounting

channels mechanically fastened to the roof. Array voltage is

developed along the length of the roof using a series string of 20

modules. Array current is developed along the height of the roof

using two (2) parallel-wired module rows.

Standoff Mounting Concepts

SaTple 9. Forty (40) unframed modules are pressure fitted in a series of

zipperlocking EPDM rubber extrusions adhesively bonded to the roof.

Array voltage is developed along the roof height using six (6)

series-wired modules interconnected by integral tongue connectors

and positioning blocks. Array current is developed along the roof

length using five (5) branch circuits. Array termination occurs

near the gutter.

Sample 10. Eighteen (18) framed and sealed panel/modules are fastened to 30

unequal leg "T" shaped brackets bolted to the rafters. The

longest leg of each bracket is overlapped by an existing shingle.

Array voltage is developed along the roof height using a series

string of two (2) panels/modules. Array current is developed

along the roof length using nine (9) panel/module pairs attached

to busbars at the top and bottom of the array. Array termination

is near the gutter along the roof rake.

Sample 11. Twelve (12) aluminum framed panels with laterally supporting "T"

struts are clamped to a standing seam insulated metal roof deck

mounted on the rafters. Each of the ten (10) gasketed modules

pressure fitted in a panel frame are wired in series by commer-

cially available "quick-connectors" beneath the modules. The

return branch conductor is placed along the standing seam within

the conduit formed by the panel frame and a continuous finish cap.

Branch wiring is routed beneath the ridge flashing into the attic

space below. Array volta ge is developed along the roof height

from two (2) panels wired in series through a junction box for

each panel pair. Array current is developed along the roof length

3-7

Standoff Mounting Concepts (Cont'd)

Sample 11. from the six (6) panel-pair junction boxes parallel-wired withinont

the attic near the ridge using redundant armored bus cable conduc-

tors.

Sample. 12. Forty-two (42) unframed modules are pressure fitted in a series of

Zipperlockine EPOM rubber extrusions adhesively bonded to the

roof of a manufactured house. Array voltage is developed along

the roof height using six (6) series-wired modules interconnected

by integral tongue connectors and positioning blocks. Array

current is developed along the roof length using seven (7) branch

circuits. Array termination occurs near the gutter.

Sample 13. Twenty-four (24) framed panels/modules are pressure fitted in five

(5) "T" shaped tracks along the length of the roof. Each track is

lag-bolted to the rafters through a neoprene gasket strip. Array

voltage is developed along the roof length using a series string

of six (6) pin connected panels/modules. An integral wiring

harness within each track terminates at a junction box on the

high voltage side of the series string. Array current is developed

along the roof height from four \'4) track junction boxes connected

by flexible conduit. Array termination near the gutter is made at

a seal fitted roof penetration.

Sample 14. Eighty (80) gasketed modules are pressure fitted between a series

of PVC hold down caps and extruded aluminum channels fastened to

the roof. Array voltage is developed along the roof height from

eight (8) series-wired modules mounted as two adjacent colunns,

each of four modules. Array current is developed along the roof

length from ten (10) series strings that each terminate in standard

junction boxes beneath the roof.

Sample 15. Eighty (80) gasketed modules are mounted over a series of contin-

uous metal pans and pressure fitted in steel battens fastened to

the roof. Array voltage is developed along the roof height from

eight (8) series wired modules mounted as two adjacent columns,

each of four modules. Array current is developed along the roof

length from ten (10) series strings that each terminate in stan-

dard junction boxes beneath the roof.

3-8

Rack Mounted Concepts

Sample 16. Eighty (80) gasketed modules are pressure fitted in a series of

PVC hold down caps and extruded aluminum channels bolted to a

slotted steel rack. Array voltage is developed along the rack

height from eight (8) series wired modules mounted as two

adjacent columns, each of four modules. Array current is

developed along the rack length from ten (10) series strings

that each terminate in standard junction boxes.

3-9

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XQCr nc &Jr--4 X3 ZLyn#04:Z ^' K- f1.>'L =.0 uucej=jT -A om

RG A-1 -CENTERS TRUSION

a^-

I=IG-A-Ia - ARRAY ENQ EXTRuL

-')9

DESIGN CONCEPT 10 ELECTRICAL - FIGURES-14

VEKjILAI, i^T1AK1

^--- QUIGIC GOf.IUF.(^."^

wof_..__.. fv/ &L.s hh

lV,' P-E HAP-1-3

6R,J,H F,L- f W/,f,/6M--4E F KALI^Lf

n

3-30

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DESIGN CONCEPT 10 MECHANICAL FIGURE 3-20

NoF-IZONTk^^EGTION

3-31

Aaf

—011.0 5w -W•/ .r r.3s 1 rwrirMlc.^rww^ ,r3i.AW

BR,AA./CN r0 B[./-r Q,A R W/R/NG.r, r. s.

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DESIGN CONCEPT 11 ELECTRICAL - FIGURE 3-21

-

w

P_A/J 1 - PV uUOULE•^^ r4,4 1 C.oc...lic..rart4-14YQl OLL! . yGwui/Y00111jW A/►1.N. .Y. .rZ^Q

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PL AM Z - PV PANEL.7'TALLEP Cl -Q QtGSOF i%-JL I TEv 1AUT"LOOP5C.ULt :

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DESIGN CONCEPT 11 MECHANICAL - FIGURE 3-22

3-33

DESIGN CONCEPT 12 ELECTRICAL - FIGURE 3-23

NON-ELECTRICAL

MODULE TO MODULEELECTRICAL

MODULE TO MODULE nacre -w-VI VCT4I CA.

434 1, z Sly" COWL BELOW U.S.E. BUS TERMINAL TERMINALP.Y. MODULE (TYPICAL) MODULE CABLE BLOCKS ATYPICAL) BLOCKS

(TYPICAL)

NOTE: CABLERUNS UNDER MODULESAND IS CONNECTED

AT TERMINAL BLOCKS

I I Y. . rv101uc ""' I

I ^ y I /,

I 1

Tb4 UWU- TCW.LG

CAru

-^" - ---

SEI l'-LOCKING SARI iEMITS AUDIBLE "SNAP', - ^-r CA cCLI R rlWHLN CLAMFiNG BARHAS CLOSED AND ELECTRIFIED BUS CABLE PIVOT PIN

FL,n4j VISA/ ! ENT7 VIA/.-

^ i

4

^ I

---,NwG A4 Cf-r• 1, BUS CABLE(1^4' TOTAL QD.)

- - - I^UL/STK^IJ I^ ^F"A:t1.nb.f[ IWIV!"

L WIRE FOPCEDINTO PLACEf OVER KNIvES 3Y CLOSING

-LANPING BAW

`JI(Z VIL'W

T`

3-34

RADIANT HEAT \ ^^REFLECTING FOILAPPLIED TO HOTTTIMOF TRUSS CHORD

BUS CABLE TO CONTROL ROOM ROOF

SELF-FLASHING COWL

ROLL ^^^333 r :" I.D.

ROOFING ^_•.' ^^kPDH GROMMET

DETAIL OF ENTRY COWL (N.T.S.)

Wn-" im A ►YJI; ^JC'ENTRY COWL

ROLL HOOFING

All

HOOF DECK

ILO ^/^ - CLalt^HOOF TAM

IN

/ GIDAIf1W. VH.J1L Y7PtIT WJT

)AT AS CLOSEDry

DESIGN CONCEPT 12 MECHANICAL - FIGURE 3-24

CLS1hJtYt1'^ viWL F4oGG VaJT —\—L^1^'"\'^ J I ...I

. _ioG 'MKMWAL eLMX -'—

tT'CM..MOIJ►.RMJ',^ CXTRIJ^IC7.^ --^

. .

A

r (70 --tPclht)

FOOT

_>^ 17CU7tlJa ^uR14CL^

Fl . A-1 -CENTER EXTRUSION

-1 vuFIG-A-Ia -ARRAY END EXTRUSION

3-35

DESIGN CONCEPT 13 EIECTF

1UNGTIOU IFR IGURs

ROOT $SALRICauRa

F 1 GURt 1ARRAY A-5eEMSLY

DOIL wIIl1YG=1 O AWGI.U1d WINCINGINGONDuIT

- I I- * I I- * i 1- + ,Jov I24Ov

:ovYom)

X12,

^ wIREIwr►Y

,L) c ouOUlr

I.zov

^TiM ^ G^NNi GTO IL .V^t^^ * ^

^^^ ^ ^ ^ FLlrlsl[o ^+Ou 17

^t MiT RAn 04^4"_ `. TMROUC•H ;OOP

sal p ' W Ili i.ITEM :- 4' . 4' MODULI, sown ^^ouNfJJ - D^i3D,(ALT[R MAT I . 2'. V" 0 ZAC:.ti wa -^MOOIJLLS)• A "AGi14T-L'AGJ^

• ^OLAtLOti' wITN LOG.KJKA9LVICL OM1TTtQ.

3-36

I^J

DESIGN CONCEPT 13 MECHANICAL - FIGURE 3-26

TRACK- A LUMIMUTA[x? ptulbiom -

GONN[GTORGtGURSO TO110-k W 1-

fIGuRG 1

TKAGK (-KQ== IwNoclaaw roamo"-

r.GTORY 16uaGOMNSG-riam

— I

1

1

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F;AM!- CUT-OUT IMWA`( Zr- GONMSGTOR.

WLAI-NTIGI4T MATING GOMMM4702L

CC o- IWAG'SaAL ) GIMILAR To AMrING•iOL-RLOGIL JJITNOu. IOGKING' TAlbtk.MODIPM0 TO FORM ASOVS RLUftKA5eG&M&L`f ).

FIGURE jFRA;vie CONNEGTog ASeEMBLY

3-37

DESIGN CONCEPT 14 ELECTRICAL — FIGURE 3-27

colrclw w w'Sam tt: - Y. • "Ate r olotl/l it" an+Me m

fet /lnlnie I1w•1 qq1 ca.eulwta (MINOR

tat0 - Nome• .1 to r. a& ItawM J.

i IOOM aFt Icw.! Wolf wr It19.I /

n atera ow e nc; • "FILM rR A tau = ta ' aPl.n1 a A oat (Iwo .ILAP (in. a sa— e -4 was tae w N►• 1 .q• qw .l a.wN.uls Yrall n terab (119.1rig earl o PLAN SAW" w wnlLM up, PY AIMA1 1100E RAN

aNO rmm swe t. Iwo we wmw o wMI Nelms SMfmck"s "Per Item. na/ w a.lw ru /letft'/.+.1101

-j It nuaw w It M rwrto-Ncla twno atoma a'^^ ^/ :OKA woven

Tli,

rwuaw (sells"tan wMM 1 le'Come ot1n 6006111

nn/.a/wells wall Iwo..

r no

*n OUR ITIV.I

"FILM rwawV~ if""M

- a77 RNt: YI nNl

/' / uM.tal MII I{V lot^• Y Ira tlala

7.19 Ned mom INl

m fWot w. tWllae

Hr 1 L.• nN* Gams am not1.IONS "01 n aeeil

%fr t IN• rkIllaw f.Yl 111. r-dIIpInVYNOIa to %= lFYlw

1"Mal: 3411 • /Oea •mlotu. LmLM%L n -^

r i^

( !Hea t elan /on /eMt: ne "LAM Slot 0 I-=M •f ella ttfsurlaw

IIa.1ao .0-M

^^ L " Niue rwlal/ am.am w w.l. a-seta

-alt/ rtteu/ .1n Illtolur ala Ialw N Mai wYF10

W. La aotf .t ltttr.lwt MISIM "1 m .tan (Iw.1

1.0 Y

1" 10 a.. h SN•t1YMte }ar- Ua/. n1YA. 10 ter I. y.^.

NO vtlw.1 wn— -sal cmw t

caawtl

Y 'ULAN ter n .CA mlan

(T Haletin It Iel

Air" .111 .1111or 'YNY or0'" Meet

1

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PV a p ll ► T FI ICTNtC ► l SCME4aT1iC

3-38

n -gnur( — nf nl^w

^' r n r.rrf ra Tltaw twu •pr,Iti s111tta

I NN•Itl waa^

DESIGN CONCEPT 14 MECHANICAL - FIGURE 3-28

! 101 --^ /1.W .. @tven M RAMIAi^ar wn(s —

slCT10i1 ^1tssra ow

All H<OIIA "limm a: •eir "W nWWII on IMCT PMJr nss

air w" •WNW w

mat, M11rrIA-

r 1 sr rAxu-

mom(_ p• t•__ _ }.-.. - .i

lr _ 1R 4i d ON

A Maua" woo w

11. '1 116

';^

-at ,Pt i nn utlrtoo Iwnls

L^• "rum

Ur ifl^ II

mcnoM D-O

Aca & .,%W

1/f' I Vr YbOY1 W f nuYMI[i f aril nn IA1l A 11/►rtr moon (l0 an lufl-

rinitl► XI/iM tiMn 111Y1iIfl — —^

O "A", td f1rM \u1on" rno Wwin \

7.0 WILL ^ I I:&IN rplt• u 114nii-^

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r 3 Dail R. w limit ll0.m il i1m an OLO

vhrC MQ(^ DOW" CW111160, W STAORIZ")

1tAa KYA .

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1

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w 11♦.

-Ij:! =4YIERT1CAL ALMMORM SUPPOPIT FITT M04P-A& SCJ"

3-39

r/ ^ r

rf

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DESIGN CONCEPT 15 ELECTRICAL - FIGURE 3-29

rata+ a9wu wt am wtA llw.l M llama or is r rrlw. slowftff .11I

• Iwo twstlQ h 11AP t0= N utra w N r. MOAp aw

1141, 111&111 A. yY .1911 A. oltllR NI j ,, alaga tM Itw. ltO t^lt^t—t I ,p Oi/tt^ IA sat .- / N A 1Mt OAI/IFR^ it to WAOM tWf (tN, w ".I

tar up-Munau —J9 -was. nil "It. , N19• .t lwO -._ rrn9 n0 (ram. • M)

La ^ N Rlw..tw uluw, PrArwAwt - rtlo up

rIIf9 tomAM11 aft 9[MAO _41111, 00. o.t,Ar

MR* a nw ^ 01111111111,1101111111111,1111I 410.1 ?am to" K IV 6K//r AIINAT NOW PAN

6sA6a /Mr

NA -wr t wr tlwl ow"tvwnul na9rtAO tea/

wr t 1/Y MLONNO ^ MaL[7.111,1111 sow. I9-""rKsas if rrlO

d A/e16 gifts I.wfor 101AO un s Jaw

rim ^ sl.w J..ow

rn9 CLM •'^ Yt• 6KI9 mom tMfr

K 9A9 JOla9

I^J- >r rat

^• eat 19CAnaa SECTION G-COCMA vr.r

n 6► tars

i'

CML I an in 3w

6111961MIM 61419.1W6r .1..fl69w6a rat MOM1 rw.1r

n 'MILM ,r M•

u 1141 [11

1r^1

JNg'1..1191 rrnr •IAAt 1rm+nc+9a

/V ARRAY VLICTTtICAL SCHFMATSM seats

3-40

a—Ttarty fla^ 1

.nn umtw Wn

rta-au IsMlfita M*nlnt oai; att ►mottatttlttta*%W P%AMWQ/M[TAL 0[CK 1^^

Wo" t.e►r

rarl. etp.1^ ter

. tae rn",Mon to

vwbl ltt0 vm[it lalg4LA" w

r t

• I

— rr est14• cm va.ggs

—^ otogr tt.atpy"go" Pun

.trsMor7 _ 1 S[CT)ON "acau r %r

Frtw s mr. rrr+_ _ wlma tlr qn

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DESIGN CONCEPT 15 MECHANICAL - FIGURE 3-30

Vt► Nos eai 1 -L

arras

I$gSnRN A-A

awA rw

—""" nP

lay Mrtta 1'lli^ \ _ ^i'/^ `. I. / la

- w MWAI/•Ip1Y tlU IaNe 1 0 VIII. TT~ l '

.^1 1/•1

SIM

YnU ple1M ^!1 i/. li l' qi - / 1 IaIY w. 1 ^ Y 4 fIlLL. [ q. 1 ^t Y NaI•1

Its "Itk,4 'ur

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3-41

A

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ry

DESIGN CONCEPT 16 ELECTRICAL - FIGURE 3-31

. iliir (wcta iillrl. 1^a • ^.Aiwa .(r rrnn ^(ln. I tiw tr it w w ~I4tiwl N tt/wwl

- w ^^, n Nl• i u lw. lrir w (lilil MI ^ —mww/ rrl. nul. (q,10mv e-t ^Tiw.i r

W la w t. nrnt A w 3owl A "a mmom140,0011111111Mae tawimaim140,0011111111

utMIIOw), J nlnc

lNll t. "scl (1Ml It" k rlint+0t7 ttol .Ni. w law t _ &W lwl r. Uwmtr. tol4 wav

SCUTN 00040 w &MAY 1100/ PLAN0MMTH Qmxv t0tLxfk-T-

—T

"' a s trl w vl • r a wititn-^^'^\lull y M1Y t(lt$ r(n1Y ,.l.ti—1160%M}^ 1

1171.t

M •i01Ai ter M.

unlnri

w "WAX"W w rt

JYJtI W14% 1111l+ -taw tarmwlR^

it m ina

►Y ARRAY nICTOiCAL 109HO AT1^l.• .e u

— .511itwiw rlt•w 1r mum inumm"

-rnwl llllnl ,wnrii l lawN n V * t/lr[1r " l/Al A~ two. IF a

r rwY lwir wow f1w. w t mltr►

— N Pon w w a. rwY st(nw 8101 to 31W t w /l/wltwo W0001, an tiw ru tOrlw nwiw.n ~

3-42

.- -ve. some v I/li/f fairw 'lIM/ M7MVM,lf. t.^, tlr \

1

X17.11. Ilfv.11r+tw urru Iwr.l

^.to "I. "Me",n1:1 Itw.lAIUM q1. IIlO1fwA

DESIGN . CONCEPT 16 MECHANICAL - FIGURE 3-32

al"WA visa & ftwit ItimMllwf y r room t.yr 1 t't: YIrAI N Itk 1.:—\UIN'111vfAnnn.le!. no I lf.c— —

I!. Y, AL. Ittlsa4

re w. w. taro Im.of w w. "GUArf xii,

`Ir.• UA ma,lf ott vivo MI/tffeM N Ysaatltaf It*.)

1811tr hlm IvNr1A MILI

-YN' r./rgtlf it Iw.nMnl.. lift"' 1..Vr 1 fir It W &ash lol.-

&.,tt trra7 Irw. tv • wroo

•--IH -f t... q . M. Wr.. 1..st1 w. w. M 177x.1

orw7 y ^fl.

in ~mmMCTIOM C-CKW VI'Ir

rlren. ,I.ra Iry w pw. ► r^1,•,

W of lrw Ir►wu411rf ^

11^ Ovlr7 11 --^► ^r{f

'I 1 - ^I oe. tar

^-tUtsa rtf 11 w.) nnf rt71M 177► .)

IH • f v17 1 N M 1 ^^ 7» . - —71A^1^ IT1► 1

.mm,

— f —1- 11

JIIIIM tIrn lau . - alIWI 77.

1rf '^ ^ ^ str

or

t.r I ^ 1 tapr/ . Ir

r• tw.

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— 444' --}

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f iT1AMif1^ F%-AN

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3.3 CONCEPT EVALUATION

Key evaluation objectives include: a) identification of major concerns

that affect concepts using the criteria discussed in Section. 3.1; and,

b) identification of each concept's significance in the optimization of

three generic concepts for least life cycle cost. Two stages of evaluations

were conducted following each team's concept presentation.. Major concerns

for proof of concept were assessed by the advisory panel using the market

penetration, fabrication, design and specification, installation, operation

and maintenance criteria. Then statistical methods were employed to rank

t.ne significance of each concept for cost optimization.

Factors that affect development and evaluation of all design concepts

are first discussed. Next factors that affect optimum use by mounting type

are summarized, followed by an identification of major concerns for each

concert. Factors that have broad applicability to design concept develop-

ment have been grouped into several major categories. A discussion of key

assumptions and evaluation observations in each category follows their

listing below.

e circuit configuration and wiring

e alignment and attachment

e reliability and operation

e codes and standards qualification

e roof construction practices

e life cycle cost estimation

Circuit Configuration and Wiring

An important assumption used was that array voltage is developed to

satisfy the voltage window of present day inverters to produce 240 Vac single

phase output for residential loads. Key considerations include: minimization

of busbar length; minimization of grounding needs; optimization of electrical

potential location and proximity; minimization of field electrical connections

and cabling; and optimization of circuit design to improve performance

reliability.

If module grounding needs can be minimized, major cost benefits from

reductions in the number of field connections can be realized using module

voltages higher than 30 Vdc at -200 C to reach present day inverter input

voltage requirements. Generic circuit configurations either develop array

3-44

voltage along the raof height with current along the roof length, or voltage

along the roof length and current along its height. In the first configuration

constant electrical potential along the eave can be maintained, as a safety

precaution, while for the second wiring costs associated with busbar length

can be minimized.

Alignment and Attachment

Major alignment concerns include minimization of individual module

positioning, reduction of cumulative positioning error and reduction of rough-

framing to finished-trim tolerance error. Panel/module attachment at the

roof/array interface must be durable and constructionally stable. The inter-

face must prevent water penetration, thermal expansion, and other environmental

hazards from causing damage to either the array or the residence. Important

criteria to evaluate the effectiveness of attachment was whether the array

surface serves as a watertight membrane. Live loads, dead loads, snow and

wind loads have been considered on a regional basis to ensure that damage to

the array or residence will not result.

Reliability and Operation

A major assumption was that module replacement would occur once every

four years, for a total of five replaced modules over the twenty-year service

lifa of the array. Among the types of degradation expected: soiling was

assumed to be minimized by nav;ral washing processes, assisted by some home-

owner upkeep; yellowing and insulation breakdown was assumed to be minimized

by ptimized module design. A fixed cell failure rate from cell cracking was

assumed to have a nominal value of one per ten thousand per year. Fatigue

and corrosion resulting in module wearout was expected to occur after 25

years.

Codes and Standards Qualification

While efforts are underway to incorporate photovoltaic systems in building

codes, specific provisions for photovoltaic arrays are not yet included.

Currently, arrays incorporated into or built onto roofs may be evaluated

under existing codes using requirements for such diverse elements, depending

on array mounting type, as roof coverings, roof structures, skylights, and

veneers. It was assumed that successful integration of the array/roof inter-

face will guide solutions to the inconsistencies of code inspection and approval.

3-45

Roof Construction Practices

Not only did evaluation of each concept consider ease of array installa-

tion preferably requiring minimal tools and expertise, it also considered

minimal departure from standard building construction practices. A key issue

of standard practice is dimensional modularity of rafter or trussed roof

framing as well as that of sheathing and roofing materials. Minimal impact on

framing will permit continued use of standard engineering design of chords and

web members provided by truss fabricators in response to critical factors such

as dead loads, concentrated loads, snow loads and truss spacing. Minimal

impact on framing will permit continued use of 3/8 in Group I plywood without

staggered joints or end blocking material using metal "H" clips to provide

the required edge support at the midspan of each truss space. Minimal impact

on roofing material will permit use of the standard 240 lb. (per 100 ft2)

asphalt shingle with a typical life expentancy of up to 25 years that employs

self-sealing tabs to provide extra protection against wind.

Life Cycle Cost Estimation

The cost used throughout the program is the life cycle cost (LCC).

Included in the LCC are the costs of installation and maintenance as well as

the manufacturing cost of the hardware under assumed annual module production

volumes of 50000 m2 , 100000 m 2 and 500000 m2 . The impact of array hardware

choices can be expressed meaningfully only by using LCC methods to reflect

application-oriented and hardware design oriented constraints. An early

evaluation was conducted to identify the life cycle cost sensitivity of

trade-offs between initial costs and replacement costs for an assumed replace-

ment scenario. A result of this study was to focus on minimization of initial

array cost for all of the design concepts considered.

Integral Mounting Concepts

Major concerns in use of integral mounted arrays include weather tightness,

alignment and attachment to rough framed rafters and electrical connection

beneath the roof.

Concept 1 uses a proven and available technology that compares favorably

with other integral concepts. Small array size appears to limit potential

relative cost reductions for such components as flashing and gasketing. Branch

circuit wiring costs appear reduced at the expense of increased internal

panel/module wiring costs. Modules may require non-standard environmental

protection at job site prior to installation.

3-46

Concept 2 combines the technical benefits of prefabricated assembly with

an aesthetically pleasing appearance. Non-standard roof framing and ability

of panel frames to resist racking appear to be the major installation concerns.

A high batten profile that may result in partial cell shadowing appears to be

the major operation concern.

Concept 3 applies a glazing technology developed successfully for the

commercial building industry to residential construction. A key concern is

the grid's ability to resist pre-installation damage and subsequent lift

forces after installation. Another concern is the amount of time needed for

sealant curing.

Concept 4 allows flexibility of either integral, direct or standoff with

minimal electrical wiring cost. One major concern is material continuity at

the intersection of horizontal and vertical mullions. A further concern is

the assurance of a watertight membrane under field conditions.

Concept 5 uses a proven and available technology appropriate for early

market penetration In custom homes. Embrittlement of the butyl tape on wood

members may require flashing for long term reliability. Module size may

require further concern for handling, shipping, snow and wind loading at the

glass thickness specified.

Direct Mounting Concepts

Major concerns in use of direct mounted arrays include weatherability

of roof connections, cell operating temperature penalties, and field cabling

requirements.

Concept 6 provides a good exploration of the potential benefits of

coextruded thermoplastics and embedded metal. Key concerns include mechanical

attachment, module alignment, moisture protection, and installation inspection.

Electrical connection concerns include module movement, access to connectors

and module polarity reversal.

Concept 7 applies a glazing technology developed successfully for the

commercial building industry to residential construction. A key concern is

the grid's ability to resist pre-installation damage and subsequent lift

forces after installation. Another concern is the amount of time needed for

sealant curing.

3-47

Concept 8 allows flexibility of either integral, direct cr standoff

mounting with minimal electrical wiring cost. One major concern is mechanical

continuity at the intersection of horizontal and vertical mullions. Further

concerns include assurance of a watertight membrane.

Standoff Mounting Concepts

Major concerns in use of standoff mounted arrays include protection of

roof penetrations, minimization of additional material and prevention of debris

and vennin collection beneath the array.

Concept 9 relies upon a module interconnector incorporated with alignment

blocks. Mechanical concerns include the need for EPDM gaskets together with

alignment blocks, capability of adhesive to hold array and close tolerances

for fastening. Further concerns include the need for detailing to minimize

collection of debris and vermin. Electrical concerns include handling require-

ments for small interconnects.

Concept 10 uses a proven and available technology that compares favorably

with other integral concepts. Small array size appears to limit potential

relative cost reductions for such components as flashing and gasketing.

Branch circuit wiring costs appear reduced at the expense of increased internal

panel/module wiring costs. Modules may require environmental protection at

job site prior to installation.

Concept 11 applies a concept developed for commercial applications to

residential applications that holds promise to minimize NOCT, and improve

array efficiency. Mechanically, key concerns include: the need for further

study to minimize collection of debris and vermin; the need to further consider

thermal expansions; and the need to minimize special roof framing. Electrical

concerns include significant grounding requirements and partial cell shading

potential.

Concept 12 relies upon a unique module interconnect incorporated with

alignment blocks attached to glazing gaskets. Concerns include attachment of

the alignment blocks to the EPOM gaskets, the capability of the specified

adhesive to withstand loading conditions and close tolerances and handling

requirements for small interconnects. Further concerns include the need for

detailing to minimize collection of debris and vermin.

3-48

Concept 13 focuses on the reduction of module installation alignment and

attachment requirements. Effectiveness of module interconnection is sensitive

to series string location that requires further study to improve interconnect

standardization. Operation concerns include the need for improvement of ice

and water drainage arrested by the horizontal rails. Removal of an entire

row of modules for one module replacement appears acceptable only with high

reliability assumptions.

Concept 14 provides a good representation of present technology capability

and cost using readily available components. Key concerns include prevention

of water leakage and the minimization of field assembled parts.

Concept 15 provides a good representation of present technology capability

and cost using readily available components. Key concerns include the minimiza-

tion of field assembled parts, and the dependence on present module construction

and performance.

Rack Mounting Concepts

Major concerns in use of rack mounted arrays include additional load and

subsequent structural requirements as well as applications limited by total

cost and aesthetic considerations.

Concept 16 provides a good representation of present technology capability

and cost using readily available components. Key concerns include minimization

of structural dead load and resistance to wind uplift.

C-49

3.4 CONCEPT SELECTION

Three concepts were selected from sixteen candidates to represent several

distinguishing characteristics. These characteristics include proof-of-concept

status, innovative design focus, and mounting type.

Concepts were classified into three proof-of-concept stages. Several

concepts that use off-the-shelf components appear currently ready for field

use. Concepts that modify methods, components or materials from other con-

struction sectors or industries may require structural and/or durability tests

prior to field use. Concepts that are based upon new methods, components or

materials may require further prototype development and testing prior to field

use. It was assumed that concept test qualification would require one year.

This would yield concept field applications in two years. Prototype concept

development was limited to two years as one of the program groundrules.

Concept field applications are expected two years after prototype development.

Concepts were classified into three areas of innovative design focus:

module design; wiring; and installation. Innovative module design features

include the use of large area (i.e. larger than lm 2 ) modules with square or

rectangular cells for improved packing density and methods that allow the

safe use of modules with open circuit voltages higher than 30 Vdc at -='00C.

Innovative wiring features include the elimination of wiring harnesses, the

use of ore-wired mounting hardware, and the safe minimization of wire size

and insulation. Innovative installation factors include minimization of

individual module/panel alignment, replacement of mechanical fastening with

mastics, use of pre-cut glazing gaskets, minimization of construction trade

constraints, and minimization of module rows to reduce the complexity of

panel frames.

Concepts using the same mounting type were compared to evaluate the

effects of design trade-offs peculiar to that mounting. Whiie reductions in

hardware/gasket costs contributed the most to lower total-net-installed costs,

the effect of changes in wiring cost, roof support costs, and material

replacement credits was not uniform. Examples of large material replacement

credits did not result in lower costs per peak watt for integral systems.

Additionally, nominal reductions in wiring cost did not y ield significantly

lower integral mounting costs. In either direct or standoff mounting,

savings from roof credits and wiring costs did not significantly reduce

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A

total costs below levels achieved through savings in hardware/gasket installa-

tion.V

The three design concepts selected are identified as concept numbers 1,

7, and 9.

Design Concept 1 represents that group of concepts fabricated with

"off-the-shelf" components using a minimum of assembly steps. This concept

relies on the transfer of skills between the commercial glazing industry and

the homebuilding industry; the use of non-standard construction practices

and tolerances appear minimized. Further design optimization may be required

for array operation and maintenance, dependent upon module reliability

assumptions. Loading, watertightness and attic temperature assumptions may

require verification.

Design Concept 7 represents that group of concepts using modified

techniques, components and materials. It minimizes individual module align-

ment and replaces mechanical Fastening. While the rigidity and durability

of the grid during installation is of concern, there appears to be sufficient

rigidity during operation. In view of the concept's technology basis from

the commercial building market, rigidity, module uplift and deflection may

require empirical verification. Further design optimization may be required

for array installation, dependent upon loading and mounting assumptions.

Design Concept 9 represents that group of concepts fabricated with new

components. Handling connectors of this size is of concern though it appears

that through optimization, standard construction practices and tolerances

can be maintained. Further design optimization in prototype development may

be required, dependent upon module size and reliability assumptions. Loading,

watertightness, and component damage may require empirical verification in

prototype tests.

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SECTION 4

CONCLUSIONS AND RECOMMENDATIONS

Three integrated array design concepts were selected by the advisory

panel for further optimization and development using a comprehensive set of

technical, economic and institutional criteria. The concepts selected are

the following:

1) An array of frameless panel/modules sealed in a "T" shaped

zipperlocking neoprene gasket grid pressure fitted into an

extruded aluminum channel grid fastened across the rafters

using off-the-shelf components.

2) An array of frameless modules sealed by a silicone adhesive

in a prefabricated grid of rigid tape and sheet metal

attached to the roof that minimizes individual module align-

ment.

3) An array of frameless modules pressure fitted in a series

of zipperlocking EPDM rubber extrusions adhesively bonded

to the roof. Series string voltage is developed using a set

of integral tongue connectors and positioning blocks that

eliminates wiring harnesses.

Further design optimization will be undertaken for these concepts to

develop design trade-off data relative to module size, module reliability,

structural loading, watertightness and component damage.

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