Photovoltaic Conversion of Sunlight to Electricity -- Considerations for Developing Countries

Weingart, J.M.

IIASA Working Paper

1975

Weingart, J.M. (1975) Photovoltaic Conversion of Sunlight to Electricity -- Considerations for Developing Countries. IIASA

Working Paper. Copyright © 1975 by the author(s). http://pure.iiasa.ac.at/276/

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PHOTOVOLTAIC CONVERSION OF SUNLIGHTTO ELECTRICITY--CONSIDERATIONS FOR

DEVELOPING COUNTRIES

*Jerome M. Weingart

November 1975 ｾ ｗ Ｍ Ｗ Ｕ Ｍ Ｑ Ｕ Ｒ

*ResearchScholar, Project on Energy Systems,International Institute for Applied SystemsAnalysis, A-2361 Laxenburg, Austria

Regents' Professor,Energy and ResourcesProgram, University of California, Berkeley,California, 94720, USA

Working Papersare not intended for distri-bution outside of IIASA, and are solely fordiscussionand information purposes. Theviews expressedare those of the author, anddo not necessarilyreflect those of IIASA.

"Basiudly, all your nalions-andthis includesCommunistｃ ｨ ｩ ｮ ｡ ｾ Ｚ ｣ ｯ ｵ Ｏ Ｌ ｪ rather be Los :1 ngeles."

ｾ ｪ ｅ ｗ YORKER MAGAZINEAugust 19, 1974

PREFACE

This paper is a part of a larger report in preparationby the

National Acadely of SciencesAd Hoc Committee on Alternative Energy

Technologiesfor Developing Countries. The purposeof this paper is to

summarizethe current and projectedstateof the art of photovoltaic

technologiesfor direct conversionof sunlight to electricity, with special

emphasison the possible significanceof such technologiesfor developing

countries.

Becausethe problemsof introducing and diffusing innovative energy

technologiesinto a society are substantiallysociocultural and only partly

technical in nature, I have included some personalobservationson the

problems which need to be overcome if technically proven and economically

interestingalternativeenergy technologies.are ever to be widely used

in developing countries. I have also been presumptuousenough to indicate

what I feel to be the main ingredientsof an effective plan of action to

develop, introduce and assist in diffusing such technologieswidely and

rapidly.

Becausethis report is preliminary, I welcome commentsand criticisms,

preferablydetailed and specific to contribute to later revision and

expansion.

PresentAvailability

Photovoltaicsystanswith 10 percentsolar oonversionefficiency

and with peak power capacitiesfran 1 watt to hundredsof kilowatts are

availablefran manufacturersin Japan, the United States,Britain, France

and rlest Gennany. Packagedsystemsfor use in rerote applications, such

as navigationalbuoys and lighthouses,enviroI'lITental m::mitoring stations,

microwave relay stationsand forest rangercamn.micationsare available

as carmercialproducts in the rangeof a few watts to a kilowatt, with

large:-systemsavailableon a custanbasis. Costs of a carrpletesystem

are daninatedby the photovoltaic array; twenty to thirty dollars per peak

-..watt, corresp:mdingto $ 100,000 to $ 150,000 per averagekilowatt installed

capacity, is now being quotedand thesecostsare expectedto decrease

by as much as a factor of four within the next few years. These systems

all incmporatesilicon solar cells producedby rrodifications of space-

craft solar cell production technology, and include batteries,voltage

and ｣ ｵ ｲ ｲ ･ ｮ ｾ regulation, and other canp:>nents.such as OC/AC invertersas

options.

Next Five Years

DurirxJ th9 caning five years, over a hundredmillion dollars will

be spentby industry and governmentin the US, Japan,W. Gennany, France

and Britain in the developnentof lower cost terrestrialphotovoltaic

p:Mer systems. During this period the emphasiswill on the researchand

developnentof new processesfor mass productionof integratedsolar

nOOules, and by 1980 integratedribbon silicon arrays incorporatingwide

apertureconcentratorswithout diurnal tracking requirerrentswill prcbably

be on the market. An interestingdevelopnentis the entry of 3 major U.S.

oil canpaniesinto this field, ( ) with a canbinedinvestmentof

approximately$ 50 million projectedover the canirxJ five years.

02

The author believesthat with a continuationof this intenseand

diversified Rand D effort that solar cell m:x:1uleswith a cost of a few

tlnusanddollars per averagekilo.-mtt could be availableby 1980, with

conversioneff icienciesapproaching15 percent.

Next 5-10 years

It is perhapsunwarrantedoptimism, but this author believesthat

there is a gcod chancefor the developrentof ccmnercialphotovoltaic

conversionarraysat costsof a few hundreddollars per averagekilowatt

) by 1985 or sooner. The integrationof such arrays into a canplete

systanincorporatingenergy storage,po.ver ronditioning and transmission

and distribJtionwill be requiredbefore theseare useful on any substantial

scalefor pJWer generationgreaterthan a few kilCMatts per system. In

this regard, availability of eronomically interestingstoragesystemswill

be a crucial factor in determining the extent to which such technology

is used. In the industrializednations the incoI1XJrationof photovoltaics

into integratedutility systemswill be the primary aim of presentprograms

and preliminary studiesare currently underway to assessthe feasibility

of doing this in a number of Europeancountrieswith an abundanceof lCM

cost pumpedstoragefacilities ( ) .

In this price range therewould be great interest in the potential

use of such technology, perhapsin the establishrrEntof local (village

and ccmnunity sized) "minigrids" with the eventualgrowth and interlinking

of these into larger and rrore diverseelectrical networks. However, if

this technology is to be transforIIEd into SOITEthing which can meet the

special technical, econanicand cultural constraintsand needsof various

!lX:'s, a deliberateand specific effort to do this will be required, since

the direct "transfer" of photovoltaic systansdevelopedfor integration

into nodernutility grids to the rerrote village level is unlikely to otherwise

occur easily, if at all. Issuesof special concernfor the !lX:'s are

discussedlater in this paper.

03

So.J.ar ｃ ｯ ｮ ｶ ｰ ｲ ｳ ｾ ｯ ｮ Technoloqies.and

the Less ｏ ･ ｶ ･ ｬ ｯ ｰ ｲ ｾ ､ _Countries

Human Well-Being in thp LOC's

The potential role of advancedsolar energv technologiesfor the less

developednations may be far more significant than has generally been

thought. Substantial improvements in the nutrition, health, housing and

educationof the two-thirds of the world's population living in under-

developedregions can be achievedonly by economic developmentin these

regions, coupled with reductions in the high ratesof population growth

that have recently prevailed there. Worldwide developmentin the pattern

establishedby the rich nations, however, implies environmentaland economic

burdenswhich the developing nations should wish to avoid, and a global

environmentalburden that may prove unsustainable. The resolution of this

dilemma may lie in technologiesand lifestyles that bypass the environmental,

social and economic pitfalls which have plagued establishedindustrial

processesand patternsof economic development. The bypassor "overleap"

process, if it is possibleat all, will require substantialcontributions

of money and technologicalexpertisefrom the wealthy and the industrialized

nations.

Role of Energy Technologies

Energy technologygoes to the core of the development/environment/

economic dilemma. Energy is an indispensableingredient of prosperity,

a major contributor to environmentaldisruption, and an important determinant

of patternsof living. The prosperity gap betweenrich and poor nations

correspondsclosely to an energy gap; the developing nations, with about

two-thirds of the world's population, account for only 15% of the world's

energy consumption. Prospectsfor narrowing the energy gap are clouded

by the uneven geographicaldistribution of fossil fuels (especiallydeficient

in Latin America and Africa), by the high economic costsof technology to

extract, convert and usefully employ energy, and by the environmental,

social and economic liabilities of the various energy sources. Hydropower,

with enormouspotential in Latin America and Africa, may flood fertile land,

04

drown revenue-bearingattractions, increaseevaporativelossesof water,

displace indigeneouspopulations, impair soil fertility downstream, and

facilitate the spreadof parasiticdiseasessuch as schistosomiasis.

Nuclear power is economically attractive only in plant sizes too large

to suit most developing countries, and it bears, among other threats,

the already partially realized potpntial for the proliferation of nuclear

weapons capability. Fossil fuels are almost prohibitively expensivefor

most developing regions alrpady, and do not representa long term source

of energy in any event. It seems likely that in the final half century

or so of massiveoil use, the industrializednations will use most of the

resources,with little available to non-industrializednations.

Solar energy technologyoffers possible solutions to many of these

problems. Historically, most advo,:atesof solar energy for the developing

nations have confined their attention to low technology, very small scale

applications, such as solar cookers, solar stills, and food drying.

Convergenceof several technical and social trends now make it apparant

that sophisticatedand innovative uses of solar energy technologiescan

play an important role in ecologically spnsibledevelopment.

Recent events as well as trends of the past few decadeshave led to

recent renewed interest in the potential constributionsof solar, wind,

and other renewableenergy sourcesto solving energy problems in the

LDC's. These trends include a) dramatic recent interestand financial

support for the developmentof a broad menu of solar energy conversion

alternativesfor production of heat, shaft horsepower,electricity and

synthetic fuels such as hydrogen, b) growing recognition in industrial

nations that energy-efficientdesign of buildings, industrial processes,

transportationsystems--- indeed, patternsof living -- can greatly

reduce energy requirementsper unit of economic good; and c) some recent

awarenessthat the achievementof a decent standardof living in developing

regions will require under any circumstancesthe ambitious and imaginative

transfersof capital and technological knowledge from the rich countries

to the poor ones,

05

As a result of a recent trip which I and three other scientiststook

for the U.S. Information Agency, in 1974, covering parts of Asia and the

Middle East, I have the ｩ ｾ ｰ ｲ ･ ｳ ｳ ｩ ｯ ｮ that the following are important requi-

sites to effective developmentin the poor regions of the world:

1) Introduction of both techniquesand the materials (energy, ferti-lizer, storagefacilities, transportation,market and distributiontechniques) to facilitate the transition of the rural farmer fromsubsistencefarming to cash cropping (with substantialincreasesin yields in the process) on a ｶ･ｲｾ large scale,

2) Provision of a reliable, low cost, non-vulnerablesourceof energyfor operating irrigation systems, farm machinery, crop drying,transportationsystemsand fertilizer production plants,

3) Substantialincreasesin the quality of life (health, diversity ofopportunity, increasedpossibilities for education, security andold age support, etc.) at the rural level which permits maintenanceof disperssedpopulations, removing the pressureon the cities anddecreasingthe costs of absorbing large numbers of people in cities,

4) Dramatic reduction in population growth, achieved in part throughaccomplishmentof 1) - 3) and

5) Developmentof human settlementswhichfor their operation on a large scale.Angeles).

do not rely on fossil fuels(Everyone cannot become Los

Accomplishing these, if it is really possibleat all, would be an

extraordinary task of almost unthinkablepr0portions. At the heart of it

will be the energy issue. Rapid upgrading of the human environment while

retaining dispersen patternsof human settlementand increasing food

production dramatically may require energy sourcesthemselveswell suited

to such patternsof settlementand rural agriculture.

The developmentof an economically interestingcommercial terrestrial

version of spacecraftsolar arrays could be one of the most important

technologicalelementsof such a transition. Suitably coupled with energy

storageand power conditioning devices and an array of simple and rugged

pumps, motors, tools, etc., low cost, long life panels which convert

sunlight into DC electricity with nomoving parts and efficiencies as high

as 20% would be an attractive technology indeed for such regions, as

well as for the industrializednations.

06

Potential Advantagesof photovoltaic Systems

Assuming that such systemsbecome economically interestingin comparison

with alternatives,photovoltaic conversion systemsappear to offer some

specific advantagesrelative to large (100 to 1,000 Mwe) fossil and nuclear

powered generationsystems, in LDC's.

These include the following:

In principle, the systemscan be highly rugged, requiring a minimumof repair and replacement.

High throughput efficiency (10-15%) of total system possible.

Modular design, permitting simple replacementof elementswithoutdowntime for entire power plant (for storageand power conditioningas well as direct conversionelements).

Possibleintegration with rooftops and other structures,permittingmultiple uses of land.

Systemscan be deployed locally, without requirementsfor massiverural electrification infrastructures; very expensivefor Asia,Latin America, Africa and parts of the Middle East.

Local deployment, minimizing transmissionand distribution infra-structure requirementson large scale. Possibility of autonomousoperation, eventually looking up with others and growing with agrid system.

Systemscan grow along with load growth, permitting full amortizationof capital investment, while conservingcapital for other purposes.(As contrastedwith the $ 300 million to $ 1 billion investmentrequired for large thermal power plants, fossil or nuclear fueled).System growth with load growth may minimize the forced growth ofdemand.

The level of technical sophisticationand equipment required tooperateand maintain such systemsis compatiblewith indigineouscapabilitiesor much closer to those capabilitiesthan nuclear orlarge fossil fuel generationfacilities.

Economiesof scale do not acrue as they do in large thermal powerplants. Small systemscan be as economicalas large systems.

Minimal environmentaldisruption comparedwith fossil or hydropowersystems. Dams decreasefertility of revenuebearing downstreamlands,flood scenic areas, and facilitate the spreadof schistosomaisisinslow running irrigation ditches.

07

No fuel requirements; particularly important to the LDC's both in

terms of the cost of primary fuels and the cost of transportationinto rural, population disperssedareas.

Systemsdo not bear the nuclear power hazardsof:

a) power plant operationalsafety, a problem in technicallysophisticatedsocietiesand a very serious issue indeed intechnically emerging societies,

b) radwastedisposal - not a solved problem anywhere,

c) diversion of fissionablematerials for weapons fabrication,blackmail and terrorist activities using radioactivematerial(not necessarilyin the form of a bomb).

08

The creation of such a "kit of parts" is going to require a synthesis

of technical, economic and socio-cultural capability in international

programsof technology development, introduction and diffusion, conducted

in an atmosphereof intimate involvement between industrializedand non-

industrializednations and regions. Although the final form, ruggedness,

suitability for local use and adaptationof thesemodular systemsmay be

simple (such as the photovoltaic array), the technology required for their

developmentwill not be.

An ultimate goal would be the developmentof technologieswhich

representsthe best synthesisof high technology and local needs, including

the ability to replicate and repair such technology locally, and within the

local economic capabilities. (I.e., the economic gains associatedwith

introduction and use of solar conversion technologiesshould not be offset

by the high costs of maintenance,repair, replacementand manufacture).

I belive that some of the ingredientsof an effective international

program to develop and diffuse such technologiesare:

1) Establishmentof a well funded, mission oriented organization(perhapssimilar to the InternationalRice ResearchInstitute)which would work as an internationalcenter (with field stations)for developmentand introduction of various solar anli wind techno-logies. Such an institute would be characterizedby:

a) outstandingsocial scientists,engineers,economistsandothers dedicatedto problem solving in the context of energytechnology related needs in developing countries,

b) tenuredpositions providing high salaries,first ratefacilities, and decent living environments,

c) hardwarecapabilities, including for example, establishmentof an international solar energy technologydevelopmentcenter, perhapsin conjunction with the emerging NaturalEnergy ResourcesLaboratory planned for the stateofHawaii in conjunction with the University of Hawaii,

d) an unusual and effective synthesisof socio-cultural andtechnical/economicunderstanding,as a crucial ingredientin the processof developmentand diffusion of technicalinnovations in a society.

2) Committment of substantial, long term financial support by wealthynations to such centers.

3) Active involvement and leadershipfrom t.he "client" regions.

09

ｔ ｨ ｾ remainderof the paper is devoted to a brief summary of the status

of photovoltaic conversionsystemsand of various projections for the

costs and performanceof such systemswithin the coming decadeor less.

10

photovoltaic Conversion

Introduction

Solar cells, usually in the form of thin films or wafers, are semi-

conductordeviceswhich convert from 3% to 30% of·i.ncident solar energy into DC

electricity, with efficiencies dependingon illumination spectrum

intensity, solar cell design and materials, and temperature. A solar

cell behavesvery much like a half volt battery whose charge is conti-

nuously ｲ ･ ｰ ｾ ･ ｮ ｩ ｳ ｨ ･ ､ at a rate proportional to incident illumination.

tntegration of such cells into series-parallelconfigurationspermits

the design of solar "panels" with voltagesas high as severalkilovolts.

Combined with energy storageand power conditioning equipment, these

cells can be used as an integral part of a complete solar electric

conversionsystem. Following their invention as practical devices in

1955, they have been used primarily for the purposeof providing elec-

trical power to spacecraft. Figure is a photographof silicon solar

cellsl their operation is describedin Fig. A Mariner IV spacecraft

is shown in Fig. incorporating four large panels designedto deliver

400 watts of DC electrical power with an incident solar illumination of

1 000 watts/m2•

The extraordinarysimplicity of a solar-photovoltaicsystem (Fig. .)

would appear to be a highly desirableenergy system for t.errestrial

purposes,both in the highly industrializednations and in the less

developedcountries. These advantagesinclude the absenceof moving

parts, very slow degradationof properly sealedcells, possibility for

modular systemsat sizes from a few watts to megawatts,and extreme

simplicity of use. However, the extremely high costs of developmentand

fabrication of spacecraftsolar arrays has discouragedany serious thought

of widespreadterrestrial use of such a technology, in spite of the

potentially attractive characteristicsof such systems. A complete

spacecraftsolar cell array costs anywhere from $500,OOO/kwe (average)

for the Skylab 10 kwe array to severalmillion dollars per average

kilowatt for early kariner spacecraftarrays.

11

DIRECT CONVERSION OFSUNLIGHT INTO ELECTRICITY

100 wa"s/ft2

(NOON SUNLIGHT)

111 1

(10 TO 20 watts/ft2

ELECTRICITY )

ANTIREFLECTION LAYER ANDPROTECTIVE COATlNG

CHEMICALLY TREATED SILICON-

POSITIVE ELEC'rRODEON BACK SURFACE

NEGATIVE ELECTRODE (GRID)ON FRONT SURFACE

DC VOLTAGE APPEARSBETWEEN ELECTRODESWHEN SOLAR CELL ISILLUMINA TED

Figure

-MANY OTHER MATERIALS ALSO SUITABLE

Simplified Representationof Solar CellConversionOperation (courtesyJ. Weingart)

Figure

12

Silicon solar cell (lcm x 2cm x .04 cm)Typically Used.for SpacecraftApplications(Courtesy NASA/Jet propulsion Laboratory)

"(,I;'!

ｾ ｩ Ｎ Ｚ Ｌ Ｚ Ｚ

ｾ Ｎ Ｇ

' ..:"..."

. ;

\"

, t'- ｾＬ

.,.'

13

');,.

I'l!...

14

THE PHYSICAL CHARACTERISTICSOF A TYPICAL nip SOLAR CELL

f4----- 2cm .. ｾ

(not drawn to scale)

.,----------

Ｂ Ｂ Ｍ ｾ Ｂ Ｂ Ｂ Ｂ Ｂ ｾ ｾ Ｍ Ｍ Ｍ Ｂ Ｂ Ｇ Ｚ Ｍ Ｇ ［

"'" 2cm

ｾＭｾＭ'fO.25 ",m

p - BASE REGIONP • In -em 0.018 IN ("'50(lJ,I)

'r"...,.".....,..,....,.l_"ＲＮＮＢＬＨＩＨＩ｟ＢＬＮＬＮＬＮＬＮＮＮＮＮＮＬＮＮＬＮ｟ｾ J

METALLIC GRID--

Ｎｾ METAL CONTACT

FIGURE 1

IllUMINATED SOLAR CEll WITH TYPICAL SOLAR CELL I - V CHARACTERISTICSAN EXTERNAL LOAD

DARK FORWARD CIIAIlALTfRI \TIC

I - -I eqv/kTo'

IYPICAl II.LUMINATED CIJAliALI[1I1 qJ(,

I _ I . I qv I kTSC 0 e

DARK REVERSE CURRENT----==="'--+-.....::::----\-----V

RODE POWER QUADRANT1-

P- REGION V mCTn

-ｾｲｊｕｎｃｔｬｏｎ

+I@-

... k3

-Rl A+

v

FIGURE 2 FIGURE 3

15

ｾＭＭＬＭＭＭＭＭＭＭＢＭＭＭＭＭ

),

"',,, ,I'"''I '"'",114 ..;.

., ｾ

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ｾＮ "

,. , L

ｾＮ '.

",

, -,

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, .'",\{

'It

<> 't:- ｾ Ｌ Ｇ ｾ Ｌ ｾ

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ｾＧ｡ＺＯＧ .... ｾｾｾ , ,.. "\

ｾ Ｇ Ｍ ｾ ｾ Ｌ Ｈ

I

\ ,} I 1_. t 1.1, I I,' I I I 1_1.1 I. I. I 1.1 I f I I )r' I. I.' I I I I I I I I I I I I i I I I .I I I • , I I I I ｊ｟ｉ｟ｾ ... I t.J....I..1 ,1...1 _' ,,_, .," . _ . ' •• '_ '_' _'.

(';' i' . "10"

!' '. .

: III ... Ｇｾ ｾＧｬ［ＡｬＧ I,;". • ......- -. -. .. , •• " .. -__ ｾ __........._ .... ｟ ｾ ......- _.... ｾ - ......;,u.... ''',."" .......,t •... , '1I"" .!.Wo. : _...ｾ "!_ ••

.' ,_I I I I , , I I I I ｉ｟Ｇｾｉ I I I I '_I I .. ; I , j , • • 1.1 I I I ..... ' I • I ,

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_ ｾ .' ••• Ｎ ｾ ｟ Ｎ .• ＬＮｊＮｯＮＧｊＮｪＮＮｾｉＮｷＧｪＮＮｏＢｌ ..,d i

.---;

'-,

-

-'

PHOTOVOLTAIC MODULE OR ARRAYｾ

I = ｾ DC ELECTRICITY

-I I - .AC ELECTRICITY

SIMPLIFIED PHOTOVOLTAIC SYSTEM

_______._, I'" Ｂ Ｌ ｾ Ｎ ｾ ﾷ Ｂ Ｇ Ｇ Ｇ Ｇ ｾ ｾ ｾ ｾ ｲ ｾ Ｎ ｾ Ｚ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｚ ｊ •• Xl_C. ;43 @ QUO e ＬＮＡＡｲＭＮｾｾｾＧ ＢＧ［ＧｾＧｾｾＧ ｾ •. ｾ

ｾ

m

17

There is now good evidpnce that with appropriatetechnological

developmentsand mass prodllction techniques, the cost of such solar

arrays can be lowered to the point where a complete system (solar

conversion, storage, power conditioning and transmission/distribution)

can compete on a life cycle cost basis with other large scale energy

system alternatives (perhapsas early as the mid-80's).

Recently initiated and very substantialprogram for the development

of commercially interestingphotovoltaic systems in the United states,

West Germany, Japan and elsewhereperhaps$10 - 20 million per year)

coupled with important developmentsin the past few years now provide

some concretebasis for such a prognosis. Important recent steps

include the developmentof continuousproduction of ribbon silicon

suitable for solar cells, improvements in efficiency and stability

of CdS solar cells, and the developmentof inexpensivewide aperture

concentrators(Winston collector).

18

TherrnQl Behavi0r 0f Silicon ｓ ｯ ｬ ｾ ｲ Cells

Silicon solar cells exhibit a decreasein conversionefficiency with

increasing temperature. Recent work by Pattersonand Yasui ( ) has

resulted in the characterizationof this behavior for 10 ohm-em and 2

ohm-em NIp sil icon solar cells over the tpJI1peraturerange -140 deg. C

to +160 deg. C, over an intensity range of 0 to 850 watts per cm2 AMO

simulated solar illumination. The higher resistivity cells exhibit a

decreasingconversionefficiency with increasing illumination at all

temperatureswithin the regime measured (above 60 oeg, C for illumination

above 250 mW/em2). The lower resistivity 2 ohm-em cells do not exhibit

this behavior - their characteristicsare essentiallylinear with

temperatureand intensity over this regime. Using the graphical data

presentedin ( ) the author has calculQted the thermal coefficients

for conversionefficiency.

The behavior of the cells at a given illumination can be reasonably

well describedby the linear expression:

P P (l + C t.. T)o

T - To

C flI,T)

where,

P is the power output at a given temperatureT,

(at a specifiedpo

is t.he power output at temperatureToillumination), and

C = C(I,T) is the coefficient of thermal degradation(conversionefficiency)

Typical results obtained from ( ) are shown below:

Cell Type ｾ ｾ ｾ ｌ Ｎ ｾ ｾ ｏ Ｉ £J2..eg C- 1)--

10 ohm-em 400 mw/cm2 -7.3xlO-3

10 " 800 " -6.8xlO-3

2 " 800 " -5.5xI0-3

19

The parameterC is constantover the range 100 to 800 mW/cm2 to within

5 percent. The decreaseof efficiency by one half percent per degree C

of increasing temperatureis a factor which must be consideredin the

design of economically optimum solar cell modules for terrestrialuse.

20MAXIMUM POWER PmaxAS FeT) FORSILICON SOLAR CELLS (J P L, 1974 )

Pmax =Po [ 1- C ｾ T ]

ｾ

-'7.3 )( 10-3

-8.3)(10-3

- 5.5 )( 10-3

e

e

b

a

SAMPLE

10Sl·em+--------:----800mw lem2

100 10Sl-em ｾＭＭｉＭＭＭＭＳｉｉｉｬｉｅＺＺＭＭＭＭＭＫＭＭＭ

400mw/em2

200-I------r----+--- 22-em ＭＭＢｾＭＭＭＭＭＫＭＭﾭ800mw/em2

Pmax ( mWe)

fＳＰＰＫＺＭＭＭＭＭｾＺＭＭＭＭＭＭＭＫＭＭＭＭＭＭＫＭＭＭｾ

150 T (OC)•

10050o-t---t--t-----il---+----t-----+----+--+--+---+--+--+--+---+--+-----

o

21

CandidateMaterials and Configurations

Literally dozensof materials, alone or in combination, possessthe

semiconductorpropertiesrequired for high efficiency (> .10) conversion

of solar radiation to electricity. A number of these have been investigated

as possible commercial solar cell materials, and three of these - silicon,

cadmium sulphide and gallium arsenide - have all been successfullyused in

spacecraftapplications.others are in experimentalstagesof investigation

ann still others, though known theoretically to be potentially interesting

candidates,have yet to be thoroughly studied for theseapplications.Table

includes a brief summary of some of these and their status.

In addition to the possiblematerials and combinations, there are many

possiblecombinationsof configurationsand processesfor achieving these

possible. Configurations include the use of elementalmaterial in thick and

thin films (silicon and selenium), variations in junction design including the

possibility for "vertical" junction cells to permit high voltage operation

(Fig. ), multiple layers such as GaAs(Al) for increasedefficiency (Fig. ) ,

and the use of graded bandgapmaterials to also increasethe possibleefficiency

above that possiblewith one or two materials. The various possibilities are

discussedin detail in the current literature (e.g., ) .Processesfor forming the semiconductorjunction include diffusion at

high temperatures,evaporationto form a Schottky barrier layer on the surface

of a semiconductor (such as silicon) (Ref. ), and chemical epitaxial growth

of multiple layers (GaA1As) ), as well as ion ｩ ｾ ｬ ｡ ｮ ｴ ｡ ｴ ｩ ｯ ｮ ( ). Base materials

can be formed by single crystal growth by various methods including dendritic

webb growth ( ), CZhocralski growth ( ), and EFG ribbon growth ( ). Thin

films can be formed by sputtering, evaporation,vapor depositionand other tech-

niques ( ). Electrodescan be attachedthrough evaporation, silk screening

and application of metal "lace" ) .

These examplesare merely illustrative of the enormouscombinationsof

materials, cell designsand fabrication processespossible. Although theoretical

investigation indicates that over a dozen possible ｾ ｍ ｋ ｭ ｘ ｾ ｈ ｍ ｘ ｍ ｘ ｍ ｋ ｍ material

combinationscan yield high conversionefficiencies and that certain fabrication

processes(such as EFG and thin film formation) can lead to economically

interestingcells in principle, the searchfor a practical near-optimum

22

3lr-----r-----..---r---------.----.....----..

28

3.02.6

ｾ T=273°K

\ 2980

" 3730

" ＴＲＮｾＰ .

" 4130

'" 523<1

' ..__ .. ｾ ｝ ［ Ｕ Ｎ ｟ ｾ Ｎ ｟

22,

IDEAL CASE

T)mlx vs ｾ ｑ\

\\\

\'Ｎ ｾ CdS

" ｾ,\

",."

-

lB

.......

1.41.00.6

ｓｽｾI /

I

I /

Gf I /

I /I /

I /

/

.--------7··

Q2

4

24···

20

..ｾ 8 -_ ...

>-uz....-u-II.II.W

Band Gap E (measuredin electron volts)9

FIGURE THEORETICAL SOLAR CELL CONVERSIONEFFICIENCY FOR SELECTED EXAMPLES

23

combination of thesewill probably take the better part of a decadeand

perhapsa hundredmillion dollars or more in funding; as much as a billion

dollars may be required. However, given an adequatelevel of sustainedfunding

and the involvement of outstandingpeople from industry, universitiesand

other centers, the goal of an economically interestingterrestrial solar cell

system seems invevitable.

24

NASAC-73-4053

••. ; .. oJ·,. ,'.,"_0t!'.. · ｾＮＧＮ

't.-----.ｾＮＬ Ｌ［ｉｾ , ,.

ｾＢ

,.".",;p,..\t-...Ｇ ｬ ｾ Ｇ Ｇ Ｇ Ｎ Ｇ Ｇ Ｇ Ｇ Ｇ Ｎ ,01'111:,,1'>1;··.ＮＮＢＮＢＮｾ ••• Ｎ Ｌ Ｌ ｾ ••• 1'#••• '... Ｌｾ ........4.-

.. '.... ' - . ｾ ./,

-! ', Ｎｾ .

Ｎｾ .

ＮｾＬＮＢＮＮＬ［ aiIJi,."""' ../j&.., - .•, •.••..•ｾ .•• _ ••••.•••.••••' : ••••.J｟ＮＮＮＬＮＮＬＮｾ［ｾＭＢＧｦＧ ...-........... .

.'

,'..

.., -

/ﾷﾷｗｾ.\ ｾ ••,•.,;f:r .'. • .p : ,. ｾＮＬ ｾ ...... " ,"

'., ,

Figure

25

•o

1:1'0--,..-..........---- tJ"""-,----,

Commercial Terrestrial Solar ConversionPhotovoltaic Module (courtesyCentralab)

•,".,,,'"

I;.

1,

I'

\. ｾ i,

,Il ,·· . ,-""yr""

.ｾＬ

; ,

. ",'"

Figure

26

1 '

i

IJ,

..."

Silicon solar cells in integral terrestrialarray with FEP ("Teflon") covering.Courtesy TRW Systems, Inc.

\

r

27

ElectricalContact

1

hv

11J. barrier ｭ･ｴ｡ｬＭＫｾＬＮＧ ｾ｟ﾻＧ＾｟＾ > "."""""'""_ ｾＺ｜ｅｭ＾ ｩｄｧＷＮｩｩＮ｡ｩＤｾｉＮＺＺ ..-.mitwlflllllli'ZLir:'.=.ｾＫＭＱＰＰ ｾ barriermetal

+-10 mil siliconｾＢＢＢＢＢＬＬＬＬｾｾ __+-11J. aluminum

(NOT TO SCALE)

Figure Structureof a Schottky Barrier Solar Cell - PossibleTechnique for Low Cost High Speed Formation of Semiconductorpin junctions for solar cell Fabrication. (Ref. )

28

51 LICONSINGLE CRYSTAL

RIBBON -------J

SUPPORTINGPLATE FOR RIBBON DIE,

QUARTZCRUCIBLE

INSIDESUSCEPTOR

CAPIl.LARY DIE FOR RlOOONGROWTH

---LIQUID SILICONGROWTH FI LM

R.FHEATINGCOIL

Figure Schematicof Solar Cell Ribbon SiliconGrowth (EFG -"Edge Defined Film Growth")(CourtesyTyco Laboratories)

29

, "1'

, ,'j

ｾ llIiI...,:... -

r,

* f. k" ｾ ｾ ｾ Ｌ Ｑ Ｌ Ｌ Ｚ ＼ .. ｟ Ｌ ｾ Ｎ Ｎ ｷ ｪ ｲ ｾ •

Ｌｾｾｾ｟ＮｾＬ .... _,.l

·'i

I

FigurePrototypeCadmium Sulphide,TerrestrialPhotovoltaicCell (Courtesy F. Shirland,' 1970)

tBASERAW

STOCK

SOLAR ARRAY MANUf ACTUn;NG

SUBSTRATEEVAPORATOR

SIMPLIFIED SCHEMATIC I CONCEPTUALAPPROACH TO THIN FILM SOLAP ARRAYMASS PRODUCTION (COURTESY F, SHIRLAND)

wo

31

'J "

· .• ﾷＢＮＢｦＬｾ .• ｾ

- ..;....... "'i ....ＬｾＮＮＬＮＮＮ

. ｾ ....". ..., ..............,,,.,,

..........ＢＧＬＮｾＮＬＮＮＢＮ

,........." ＧｴｬｬＱｾＢ［ＮｴｾＢＢｾＮｾＮ｟ＢＮＬ'·1t$'tbUi 1he,."," ,.1.... ,

'l''lｾＬＮＧＱＤ ...Ｑ Ｎ Ｌ Ｌ ｾｾ ｾ Ｎ Ｇ .> ..,

Figure EFG silicon ribbon being pulled from themelt. CourtesyTyco Laboratories (1974)

32

'..

Ｇ ｾｾｾｾＢｉＱＱＱＢＢＢｉＱＱＱＢＢｩｉｉｬＢＢｬｩｩｬｩｾＮｾＺＺｾＺ )Fabricated(prototvpe .)ltaic Array Laboratorles

Terrestrial photovo (C urtesy Tyco

Silicon aFrom EFG RlbbonFiqure __

Ｂ ｾ

.."

:',

,::: ...

.• '''!'''.

Ｇｾ ＮＺｾＢｾｾ ｾ Ll ! ' , I " J I I I ': .

33D R AFT

Economicsof Photovoltaic Systems

J. Weingart

Introduction

The economICSof the large scale energy systemsused in the industrialized

nations (and to a considerablylesserextent in the LnC's) vary substantially

from the economics of small scale energy systemswhich might be used in developing

countries. In both sets of circumstances,however, the basic capital costs of

various system alternativesmust be establishedbefore any procedureto calculate

final costs of energy delivered to the ultimate user can be employed. Becausethe

author is a physicist and not an economist (particularly an economistof energy

use in the LnC's) I will only mention briefly the issueswhich must ultimately

be carefully consideredbefore final assessmentof the usefullnessof photo-

voltaic conversionsystemsis made.

This sectionwill review the current and projected costs of solar conversion

elements (solar cells), solar conversionmodules (fully integrated terrestrial

array) and solar conversion systems including conversion, storage, power conditioning

and transmissionand distribution. In addition, various estimatesof the rate of

market growth for photovoltaic systemsas a function of time and systemcosts are

reviewed and their credibility discussed.Finally, this sectionwill conclude with

an examinationof the relative first and life-cycle costs of various solar photo-

voltaic and non-solar energy options for electricity production, in the context

of the LnC's. I begin, however, with a brief discussionof the systemsconsiderations

involved in evaluating the total costs to the final user of a photovoltaic system.

Systems Considerations

The costs of energy from a solar energy conversionsystem in an Lnc include many

factors beyond the capital cost of the solar conversionmodule. Capital or initial

costs include, of course, the costs of the array modules, including support and

orientation structures,plumbing (if forced cooling is used) and other elements,

including batteries, inverters and other power conditioning equipment, and hardware

for local distribution of electricity. Additional capital investmentcosts include

2

34

provisions for replacementparts, tools, chemicals for cleaning surfacesand

inhibiting corrosion, and possible backup systems, such as inexpensive internal

combustionengines plus generators,and occasionaluse of fuel. Other costs

will of course include the costs of packaging and transporting the system elements

to site, fees and tarrifs for importati0n, and labor costs for assemblyand

operationof the system. Still additional costs include the developmentof a local

infrastructure to handle replacements,training ｦ ｯ ｾ people to use the equipment,

developmentand printing of manuals for instruction in system operationand

possible additional costs associatedwith local institutional factors, such as

the need to monitor how much each member of a settlementis drawing (electricity)

from the system. Other social costs might include payment to people who make

their living delivering kerosine or other fuels which are totally or partially

displacedby the solar systems.There are precendentsfor such considerations**A partial list of such costs is shown in tahle

Finally, ｾ ｨ ･ cost of capital will be an important factor in determining the

cost of energy. In a photovoltaic system where the costs of the system operation

depend primarily on the total capital investment in the delivered system, the

interest rates applied to the loans will be extremely important, since the amorti-

zed costs of electricity will be almost linearly proportional to the interest

rate.

** Maria Telkes tells of an incident on a Greek Island where a large solar stillwas installed under her direction. The glass plates were mysteriously broken nightafter night soon after the still went into operation. Investigation showed thatboys who had been earning their money bringing fresh water to the villages fromthe hills were resonsibleand the damagedid not stop until they were suitablypaid.

35

Cost Componentsfor a Photovoltaic System

Capital Costs

Equipment

Solar conversionmodules including mechanicalsupports,heat transfer (active or passive),orientationmechanisms,concentrators,etc.

Batteries

Power Conditioning (Inverters, voltage regulation, currentstabilization, transformers,etc.)

Local transmissionand distribution components, including cables,plugs and connections,switches and relays, etc.

Transportation

Packagingfor shipment

Transport from sourcesto LDC's (for those componentsnot producedlocally)

Internal transport

Fees

Import dutiesTaxesHidden costs

Support Locally

Spare partsToolsManualsTraining

Array Deployment

Cost of landLabor and materials for deploymentOn-site structuresfor housing storagebatteries,power conditioning equipment,

etc.

36

Continuing Costs

Equipment

Replacementcomponentsfor damagedsystem elements

Replacementof batteries (3 to 5 years) and other elementsdue tocorrosion and other forms of degraoation, engines after 3 years

Tools, manuals. etc. which are neededcontinuously and which break orwear out (or are stolen, sold or otherwisemade unavailable)

Maintanenceand Operation

Labor for maintaining equipment, possible costs for night time protection.

Labor for operating system, including handling billings or othertechniquesfor dividing up local support of the system

Capital Costs

Interest on capital borrowed to purchasesystems

Local taxes and other fees

Possibility of taxes or fees of ｶ ｡ ｲ ｾ ｯ ｵ ｳ kinds imposed locally.

Fuel

Fuel costs for backup system(s) which may be required to minimize risk ofsolar system outages to acceptablelevels

37

Solar conversionelements- current costs

Of the var10US types of photovoltaic devices, only silicon solar cells have

really become an establishedproduct, although CdS cells have been used in

spaceapplications (USA and France) and GaAs cells were used by the USSR in

near-sundeep spaceprobes. Although various types of cells will be discussed

under "future costs", this sectionwill be limited to a discussionof the

presentcosts of silicon solar cells.

The cost of a cell can be unambiguouslyexpressedin terms of the cost per

unit area of the finished device. The actual cost of energy produced in a working

environmentwill depend on such factors as the efficiency of the cell as a

function of tempearture,intensity and wavelength; insolation patternsand

other environmental factors. Since the realistic applicationsof such cells

will be in integratedmodules, the final costs must be determined in terms

of the performanceof thesemodules and not of the cells alone. However, in

order to understandthe costs of the modules, it is important to understand

the characteristicsof individual solar cells or conversionelementsfirst.

As discussedearlier, the processof fabricating silicon solar cells consists

of a number of steps leading from sand to a completedcell, followed by integra-

tion into an array unit. Each step of processingand fabrication entails added

costs. Sand is available for about a half cent per Kg. Metalurgical silicon, with

a purity of approximately95 percent, typically used in steel making, costs about

sixty cents per Kg. Chlorosilane (SiHC13

) costs about six dollars per Kg (Si

content) and is available at purities exceeding99,999 percent. The

usual use of such material is for production of silicones and pure polycrystalline

silicon. This polycrystalline silicon is 99.9999 percentpure and is usually used

for semiconductordevices. The 1973 costs were approximately$ 65 per Kg.

Single crystals of silicon grown by the Czochralshimethod cost $ 250. per

Kg and Silicon solar cell blanks cost approximately$ 1500. per Kg. This final

calculation is for silicon solar cells 0.01 cm thick with a 10 percentconversion

efficiency (AM1) The eqUivalent cost of the solar cell blanks producedby this

process (of cutting and slicing the cylindrical single crystals of Si) is

$ 3500 per Kwe (peak) and roughly $ 14,000 to $ 20,000 per averageKwe. The

current price for individual sili.con solar cells is approximately $ 10,000 per

peak kwe ($ 40,000 to $ 60,000 per averageKwe) and the cost of a completed

array (with or without batteriesand power conditioning, since theseare

relatively cheap) is $ 30,000 to $ 70,000 per peak Kwe ($ 120,000up for average

power) •

38

CURRENT MATERIALS COSTS IN SILICON SOLAR CELL FABRICATION

COMPONENT

SAND

METALLURGICALGRADE SILICON

TRICHLOROSlLANE(SiHC1

3)

$/Kg

.005

.60

.66

.51

6.006.006.58

a$/Kwe(peak)

.01

1.402.50

14.0023.00

.30

.12

2.751.54

REFERENCE

Ralph (1)

Ralph (1)Lesk (2)Wolf (3)

Ralph (1)Lesk (2)Wolf (3)

SEMICONDUcrOR 60.00 140.00 Ralph (1)

GRADE SILICON 350.00 Goldsmith (4 )

65.00 250.00 30.00 Lesk (2)

59.80 14.00 Wolf (3 )

60.00 lIes ( 5)

60.00 Crossman (6)

SINGLE CRYSTALSILICON

250.00300.00

600.00 Ralph (1)!les (7)

SINGLE CRYSTAL 1300.00SILICON SOLARCELL BLANK

3000.003200.003800.00 460.00

Ralph (1)Goldsmith (4)Lesk (2)

COMPLETE SOLARCELL

COMPLETE SILICONCELL ARRAY

TERRESTRIALSYSTEM(Battery,Power cond.)

SPACECRAFT ARRAY

5000.00 (extensionof 1973 tech.)60,000.00 (spacecraftcell)

30,000

30,00040,000 - 70,000

Ralph (8)Goldsmith(4}

Greeley (9)

Lindmeyer(9)Centralab(9)

a} These costs are computedon the basis of a ten percentconversionefficiency at Air Mass One (AMI) incident solar radiation. Variation

in computedcosts reflects differing assumptionsabout the cell thickness.

39References

Current Materials Costs in Silicon Solar Cells

1. E.L. Ralph, "Material Factors in Manufacturing Solar Cells" Ref. I

2. LA. Lesk, "Large Scale Use of Single Crystal Silicon for SolarEnergy Conversion" Ref. I

3. M. Wolf, "Methods for Low Cost ｾ ｡ ｮ ｵ ｦ ｡ ｣ ｴ ｵ ｲ ･ of IntegratedSiliconSolar Arrays", Ref. I

4. P. Goldsmith, "Evaluation of Solar Cell Cost Predictions", Ref. II

5. P. lIes, "PolycrystallineSilicon Solar Cells - The Centralab-Dow Corning program" Ref. II

6. L. D. Crossmanand L.P. Hunt, "Proposal for Low Cost Silicon Processes"Ref. II

7. P. lIes, private communication (1973)

8. E. Ralph, "Silicon PhotovoltaicDevice DevelopmentPlan", Ref. II

9. A. Rosenblatt, "Energy Crisis Spurs Developmentof PhotovoltaicPowerSources", Electronics (G.B.), 4 April, 1974

NOTE: The various referencesquoted ranged from 1972 to 1974; some variation inprices over this time have taken place in terrestrial arrays. The pricesshown are, with the exceptionof the projected costs of terrestrial solarcells, reflective of the current market environmentfor silicon materialsand photovoltaic devices and arrays.

ReferenceI: Procedingsof the Symposium on the Material ScienceAspectsofThin Film Systemsfor Solar Energy Conversion, May, 1974. Publishedby the National ScienceFoundation/RANNunder Grant No. GI-43795Available from NTIS

ReferenceII: Workshop Procedings:PhotovoltaicConversionof Solar Energy forTerrestrialApplications, Vol. I and II. october, 1973. Publishedby the National ScienceFoundation/RANN under Grant No. AG-485.Document No. NSF-RA-N-74-0l3

40

The processfor producing solar cells (current technology) from silicon can

be automatedto reduce the costsof terrestrial arrays to perhaps$ 25,000 per

kwe (average) However, as Wolf puts it:

"While the application of existing silicon solar cell technology toterrestrial solar energy utilization would be technically feasibletoday, the processmethods by which these cells are fabricated, evenif fully automated,do not ｨ ｡ ｶ ｾ the capability of reaching the mentioned(approx. $ 1000 per averagekwe', cost goals. It is thereforenecessaryto develop an entirely new fabrication processfor silicon solar arrays"

(emphasisadded)

Potential for Reduction of Silicon Solar Cell Array Costs

It is clear from Table that two important areas for developmentof

new techniquesto reduce costs is the production of silicon solar cell

"blanks" of suitable quality (as measuredin defect and impurity concentrations)

and in the conversionof the blank to a finished cell. Productionof solar

arrays or modules at interestingprices (under $ 1000 per averagekwe) will

require a mass production technique for combining the cell, mechanicalsupports,

protective diodes, electrical contactsand connections,transparentcovers and

other componentsin an efficient manner. One particularly important component

in the completedmodule is a concentrator,to increasethe effective area of

the solar cell or conversionelementwithout a significant increasein cost.

Since the costsof metal or metalizedglass or plastic concentratorswill be

ten to a hundred times less expensiveper unit area than the cells themselves,

the :integrationof concentratorsinto a finished module may be the important

final "stage" of cost reduction processesto achieve an economically interesting

terrestrial photovoltaic system.

Reduction in the Cost of Suitable Quality Silicon

Estimatesby Ralph (__) and others indicate that an increasein present

solar cell production by 5 orders of magnitudewill result in a reduc-

tion of the cost of semiconductorgrade silicon by a factor of only two.

(Figure , Table ). The reason is that the projecteddemand for

polycrystalline semiconductorquality silicon for all uses will not be

sufficient, in the view of a representativeof a major supplier of silicon

to reduce the price substantially.Such a view is open to challenge.The

projecteddemand for semiconductorsilicon is shown in Figure

41

Solar Conversion Modules - Current Costs

Solar conversionmodules, like the Centralabmodule shown in Figure , are

currently available at a price of $ 30,000 per kwe(peak) The author has not

seena detailed breakdown of the costs of componentsand assemblyof these

modules so a detaileddiscussionof ｴ ｨ ｾ economics is not possibleat this time.

'(Information has been requestedfrom a number of the module manufacturers.)

The current costs of $ 120,000 to $ 15,.,000 per kwe(average) can be reduced.

42

Production is estimatedby Union Carbide ( to be approximately one

million Kg in 1975, growing at 20 percentper year to 150 million Kg in

the year 2000. Such increasesin production might result in substantial

price reductions. If, however, price reductions (in presentdollars)

follow the industrial experienceof the past for many industries*, the

cost reduction will be approximatelyby a factor of 5.3. It seems therefore

that reduction in the cost of semiconductorquality silicon will not alone

make the difference required.

IncreasedConversionEfficiency, DecreasedThicknessof Cells

A number of expertsbelieve that solar cells can be made with a

conversionefficiency approaching20 percent (AM1, 20 deg. C) with

the usual thickness (.025 em) and with a conversionefficiency of

10 percentwith a thicknessof 0.01 cm. Increasedefficienciesat

a given thickness (or an increasein the ration of efficiency to

thickness) will reduce the costs further, although only another factor

of two or so is to be expected.

New FabricationApproaches

A large number of techniquesfor reducing the cost of the cell blank

and of subsequentprocessingof the blank to produce a finished cell have

been discussedextensively in the open literature. Productionof lower

cost blanks for cells, using processesto convert relatively low cost

metallurgical grade silicon or trichlorosilane into finished blanks, include

fabrication of polycrystalline and single crystal ribbons and sheets,ion

depositionof thick silicon "films" and a number of other techniques.

* Past experiencehas shown that the price of many materials and productsdecreasesin proportion to the cube root of the production level. Thismea.ns an increasein production by a factor of 150 would result in acost reduction of a factor of 5. (

43

Of thesevarious techniques,discussedelsewherein this report, only

one is sufficiently advanced, in the author'sopinion, to estimatethe

potential cost reduction in cell blanks and finished cells. This is the

techniquedevelopedby Tyco Laboratories (Waltham, Massachusetts)for

the production of continuoussilicon ribbon of sufficient quality to produce

solar cells with conversion ･ ｦ ｦ ｩ ｣ ｩ ･ ｲ Ｎ ｾ ｩ ･ ｳ in excessof ten percentunder

standardconditions. The processis known as the EFG or Edge-DefinedFilm-

Growth techniquE' ( ). In this tecn:1ique a l'.seed!' crystal of silicon is dipped

in a bath of molton silicon and a film is pulled through a capillary die

(figures and ) to produce a ribbon. Ribbons of one inch width

with thicknessesdown to .008 " (.02 cm) have been continuouslypulled at

rates of one to one and a half inches per minute. A detailed economic

analysisof this processhas been carried out on the assumptionsthat

multiple ribbon growth from a single machine could decreasecosts. The

parametersare shown in figure • Mlavsky estimatesthat with

silicon at $ 22 per Kg, finished solar cells could be producedfor the

cost of $ 165/kw(peak, AM1, 10 percentefficiency, .004 " or .01 cm thick)

or between $ 500 and $ 825 per kilowatt average.

His estimatesare that a cell blank could be produced for costs

equivalent to $ 120 per Kwe(peak), a reduction of 25 over the cost

of cell blanks preparedfor convetionalcells, and a factor of ten better

than projectionsof improved technology (lower sawing losses, ten percent

efficiency at .01 em) using otherwise current techniques.

Cell effic.

Silicon lossin cell mfg.

Thickness

Silicon cost

Current Technology

0.10

.60

.03 cm

$ 60/Kg

Tyco Proposal

0.10

.30

.01 cm

$ 22/Kg

RelativeAdvantage

x 1

2

3

3

x 18

44

ESTIMATES OF PHOTOVOLTAIC (SILICON) CONVERSION

ELEMENT COSTS (Mlavsky ( )

ECONOAICS OF EFG SILICON ｾｉｂｂｏｎ

ASSUMPTIONS: • MULTIPLE RIBBOlt GROWTIf: 20 AT ortCE.

.• nU1ENSIONS: 2 INCH x 0.00If INCH

• YIELD FROl1 RAN ｾＱａｔｅｒｉａｌＺ 701

• MINIMUM UNIT ｾｾｎｕｆａｃｔｕｒｉｎｇ OPERATION:12 MACHINES WITIf ANNUAL OUTPUT OF30010001000SQUARE INCHES (1001000 POUNDS)

-20 HW-

ｾｕｆａｃｔｕｒｉｎｇﾷｃｏｓｔＭＺ N $15/LB PLUS RAW SILICON COST

RIBBON TO CELL COST: (ESTIMATE) $lO/Ll

RAW SILICON TO CELL COST: S25/LB

FOR S10/LB RAW SILICONI AND 10% EFFICIENT CELLSI,

CELL COST- -, S165/KW (PEAK)

-DIRECT LABORI KATERIALSI AND MANUFACTURING O/HI INCLUDINGUTILITIES AND EWIPI1EHT. DEPRECIATION.

TYCO LABORATORIESI INC.

.,

45

The difference of roughly a factor of 20 is shown above. The basis for

the cost estimatesfor the silicon ribbon in mass production comes from

extensive industrial experiencewith an analogousprocessfor the production

of large quantities ( m tons/year) of single crystal, gem quality

synthetic sapphirefor use in high inteRsity lamps for highways and other

applications.The processof fully commercializing the EFG ribbon and

tubular sapphireprocesshas resultedin good cost estimatesfor an virtually

identical industrial processusing silicon. The figure of $ 165/kwe(peak)

is based, according to Mlavsky ( ), on a detailed calculation of the

componentsof direct labor, materials, and manufacturingoverhead, including

utilities and equipmentdepreciation.

Use of Concentrators

Mlavsky estimatesthat the incorporation of a collector (in particular the

Winston collector discussedbelow) into a terrestrialphotovoltaic module

incorporating the EFG silicon ribbon solar cells could result in costs of

approximately $ 200 per kwe (average) and a price of perhaps$ 4OO/kWe(average).1

Assuming that these estimatesare low by a factor of 3, the availability of

a module at $ 1200 per kwe averagecould result in electricity in LDC's

at competitive prices providing the initial capital were made available for

purchase. A detaileddiscussionof the effect of concentratorson silicon

solar cell performanceis presentedin Attachment A.

46

Use of Concentratorswith Solar Cells

Introduction

Even if the more is realized optomistic economic scenariosfor the EFC, ribbon

silicon solar eells ｡ ｾ ｴ ｴ Ｒ ｡ ｬ ｬ ｹ bappP.ns, the cost of the cells alone will still be2on the order of $ 165/Kwe(peak} = $ 825/Kwe(average)or $ 161m.

One appealingapproach, at least in theory, to reducing the costs

of photovoltaic arrays, is through the use of concentratorsto increase

the effective areasof the photovoltaic conversionelements. If the

cost per unit area of the solar cells is significantly higher than the

per unit area cost of a concentrator,the total cost per installed

kilowatt can be reduced through integration of solar cells and concen-

trators. The costs of mass producedconcentratorsfrom aluminum, aluminized

plastic and other materials are estimatedat one to two orders of magnitude

less than the cells themselves.

A number of things occur simultaneouslywhen the optical flux incident

on a solar module is increi'lsed. First, the equilibrium temperatureof the

module, determinedby the equilibrium between incident radiation and the

energy transportedfrom the module by radiation, convection and conduction,

will increase. (Fig. In addition, the efficiency of the conversion

element or solar cell is a decreasingfunction both of increasingtemperature

and increasingintensity of incident radiation. (Fig. and As the

concentrationratio increases,the optimum cell design will change, the

cooling systemwill become more complex (and presumablymore expensive)

and the tracking requirementsmore stringent. Work is underway ( ) to

determine the economically optimum mix ()f cell design, concentrationratio

and concentYi'ltor design, cooling system and module confjguration.

Disadvantagesand Advantagesof Using Concentri'ltors

The advantagesof usinq a concentratingoptical system with a photo-

voltaic element include the potential for significant (factor of 5 or

greater) in the installed cost per Kwe of the module, possibility of rr.>ductlon

47

dual mode operation to provide heat (through cooling water) as well as

electricity for local purposes,and, in the event of scarcematerials

(relative to demand for photovoltaic Jevice use of them), the opportunity

to significantly "stretch" the available supply.

There are also, however, a number of disadvantagesin such schemes.

As the concentrationratio increases, ,0 will the complexity and cost of

the module. Concentrationfactors above 4x will require tracking mechanisms

and possibly simple finned heat exchangersfor air cooling. Concentration

of a factor of lOx and above will probably require water cooling with

silicon and CdS solar cells to minimize the decreasein conversion

efficiency (0.5 percentper degreeC increase) with increasingtemperature.

Solar cell efficiency will falloff somewhatwith increasedillumination

above lOx and the high temperaturesplus larger differentials in high

and low temperaturesof the module could result in shorter lives for the

active components. (This may be offset by the availability of spares).

In addition, a systemwith a forced cooling systemwill experiencefailures

which would result in probabledestructionof the active elements.

Finally, systemswith concentrationratios above 4x will, in general, be

able to make use only of direct solar radiation and many of the LDC's

are in tropical and semitropical regions with a very high percentageof

diffuse radiation. Only combine concentrationwithout tracking requirements

and with acceptanceof some diffuse radiation as well as direct radiation.

Some of these disadvantagesare not as important as others. A high

systemmay be sufficiently lesR expensive in first costs but concentration

higher in operation costs, due to periodic replacementof deteriorated

elements, than a lower concentrationsystem. The system with lowest first

costs will probably have an economic advantagein a society where initial

capital is hard to come by but where maintanenceand operationcosts can

be borne. The availability of concentrationsystemswill make it possible

to make some tradeoff in first costs againstoperatingcosts in a way

which may be to the advantageof an LDC.

48"?1 .'

Examplesof ｃ ｯ ｮ ｣ ･ ｮ ｴ ｲ ｡ ｴ ｾ ｾ ｾ ｨ ｾ ｾ ｾ

A number of approachesto integrat.ion of solar cells and optical

concentratorshave been explored over the past several decades. Both

single axis and double axis ｣ ｯ ｮ ｣ ･ ｮ ｴ ｲ ｡ ｴ ｯ ｾ ］ can be used. A single axis

concentratoris essentiallya reflective "trough" with the solar cells

located at the bottom, as shown in Fi.g. Simple modular channel

concentratorsdescribedby Ralph ( ), Zarem and others oan

concentrateboth direct and diffuse radiation with an effective concen-

tration factor 2,5 to 3. Tabor later showed ( ) that a maximum

concentrationof approximately 4 was possibleusing such planar concen-

trators. An "egg crate" concentratorsystem was proposedover a decade

ago by Ralph ) using aluminized plastic (Fig. ) .

Parabolicor focusing troughs can achieve concentrationsof a factor

of twenty or more, but can make use only of the direct solar radiation

and must continuously track with the motion of the sun.

Two axis parabolasof revolution can increasethe concentrationto

a factor of 100 or more (as in the caseof other axially symetric

concentrators,such as the Casspgrainiansystem shown in figure and,

like the single axis concentrators,track the motion of the sun and can

collect only direct solar radiation.

The Winston Collpctor

A potentially important contributi.on to the reduction of photovoltaic

array costs has been made by Winston working with several colleagues,he

has invented the ideal cylindrical light collector. The collector, shown

schematically·in Fig. , consistsof a reflective trough whose walls are

shapedin such a way to concentratethe maximum light possibleconsistent

with physical principles. As Winston describesit (

"The ideal cylindrical light collector is capableof acceptingsolarradiation over an average8 hour day and concentratingit by a factor

49

Figure The Winston Collector in VariousConfigurations (Ref.

z

y

:nd wall

Parabola

L

FocuS ofpo rabol 0

Alis Of)parabola

so

10

ｾo4JtJaJ..........ouc:'o,j,J

IIIt:ｾ

ｾ

51

of 10 ｷ ｩ ｴ ｾ ｾ Ａ .. diurnal ｴ ｲ ｡ ｣ ｫ ｩ ｾ ｾ of the sun. This is not possiblebyconventional imaging techniques. The ideal collector is non-imagingand possessesan effective r!lative apertureof 0.5.•. The efficiencyfor collecting and concentratingisotropic radiation, in comparisonwith a flat plate collector, is just the reciprocal of the concentrationfactor."

(emphasisadded)

The ability to collect and concentratea portion of the indirect or

diffuse ｲ ｡ ､ ｩ ｾ ｴ ｪ ｯ ｮ is by itself not a particularly significant feature of

this collector. In an environment consistingof 70% direct and 30%I

diffuse radiation, with a concentrationfactor of 3, one-third of the

diffuse radiation of the total insolation is c'")llect.ed alone; wit.h t.he direct

radiation. This increQsesthe total radiation collected by only 13% -

useful but not really significant. In an insolation pnvi.ror.mf:1': in which

virtually all of the radiation was scattered (high clouds for example),

the use of concentratorswould redirect no more diffuse light to the

solar cells than if thpy bad been laid out with the same spacesbetween

them without any concentrCltors.

The much more important aspectof the Winston collector, in terms of

photovoltaics, is the ｾ ｢ ｩ ｬ ｩ ｴ ｹ to achieve a concentrationof direct radiation

by a factor of 10 ｷ ｩ Ａ Ｚ Ｎ ｜ Ｚ ｬ Ｙ ｾ ｾ ｾ ｟ ｴ Ｚ Ｍ ｟ ｾ ｾ ｾ ｾ Ｎ Ｎ Ｎ Ｎ ﾣ ｾ Ｎ Ｎ Ｎ Ｎ Ｙ ｩ ｵ ｲ ｮ ｡ ｬ ｴ ｲ ｡ ｣ ｫ ｩ ｾ ｾ Ｎ This feature would

be ･ ｸ ｴ ｲ ･ ｾ ･ ｬ ｹ important in situations in which ·the collectors were at a

fixed orientation (roof tops) and where interesting economicscould be

achievedonly thc-ouqh concentrationor in which the cost of a tracking

mechanismwould be prohibitive.

Note: These collectors dlso take on special significance in conjunctionwith flat plate thermal collectors, since they permit much higherconversion efficiency of sunlight to heat at temperaturesrequiredfor absorption refrigeration or driving organic fluid rankinecycle turbines than possiblp without concentration.

The concept evolved from the developmentof an ideal optical collector

used for the collecting of Cherenkov radiation (Fig. ). This particular

collector is a hollow, axially symetric conical shape. The extensionfor

the purposesof solar energy collection has been to a trough shapedcollector

S2

whose cross section is identical to that of the conically shapedconcen-

trator.

The effective apertureof such a concentratorcan be increasedthrough

the use of a secondconcentratorincorporuting a fluid of refractive index

greaterthan 1. In Fig. Winston has indicated how an increasein concen-

tration by the ration n2/n

1(or n

2if ｴ ｨ ｾ first medium is air) is obtained

through a two stage concentrator. In such a concentrator,the fluid with

refractive index n2

might also act as a thermal transfermedium, to

maintain the solar cell at some establishedtemperatureand possibly use

the heat for other purposesas well .

In the view of the author. (JMW), the coupling of the Winston

collector and the EFG Tyco silicon ribbon solar cells appearsthe most

promising near term otpion for a major breakthroughin reduction of

photovoltaic conversionmodule costs.

of silicon convertors).

(See section on economic aspects

ConcentratorType CcncentrationFactor Tracking Requirements References

Flat plate 1 non

Flat ｰ ｬ ｡ ｴ Ｈ ｾ

truncated

iwith Ｍ ｾ Ｍ Ｍ Ｍ j

pyramid 3 seasonal I,I

I

c.nw

,Ii

none

seasonal- 10

"" 3-4

1. __

Winston

ｾ ｯ ｊ ｩ ｮ ｳ ｴ ｯ ｮ

Low concentration

High concentration

1II

III________-h ｾ · I

!

Parabolic trough 20 diurne

! "- -----.--;------ Ｍ Ｍ ｬ ｾ Ａ ---------------+------------i

I, Parabolaof revolution i I I

Cassegrainian I >50 diurne I i. i \ I

m

54

\ I\ I\ I',J--- \-----1

//

//

//

//

!:

ｾＡｾ.J

I,I

ReflrJctor (41

Figure FLAT MIRROR CONCENTRATOR (Zarem, Ref.

55

Fig. TruncatedChannel ConcentratorDesign (Zarem, Ref.

CassegranianCollector Design (Zarem, Ref.

Figure

57

Production and Cost ScenariosFor Photovoltaic Systems- A Credibility Assessment

The production scenarIOSshown in Figure representa highly

optimistic view of the future of photovoltaic systemsproduction rates. The

rough estimatesby Weingart and Weyss ( ) shown in Figure suggest that

production rates of 10 to 100 Mwe(peak) per year will occur when the cost of

the delivered systems is below $ 1,000 per Kwe (rated). Although these estimates

are only an attempt to scale the discussion, it seems likely that the future

experiencewill roughly resemble the indicated guess. The "gap" in Figure

indicates the assumptionby Weingart and Weyss that the costs of photovoltaic

arrays produced by new techniques,such as EFG production of ribbon silicon,

will take a quantum jump downward. The "high cost" range for the photovoltaic

systemsrepresentsthe region attainable through various levels of production

sophisticationbased on existing technology. The best it appearspossible to do

with extensionsof current silicon technology is $ 20,000 per kwe(rated) for

a terrestrial array. The "low cost" regions representsthe product of new

technology in the case of silicon arrays, a highly sophisticatedversion of

the CdS technology or a new production technique, and new techniquesfor thin

film device fabrication. Only the Tyco EFG ribbon growth technique for silicon

appearswell enough advanced to permit some responsibleestimatesof the cost

of a terrestrial solar array In this low cost regime. If we assumethat the

$ 30 million invested by Mobil in the new Mobil-Tyco Solar Energy Corporation

is to generatea return on investmentof 20% per year before taxes, and the

finished arrays cost $ 1,000 per kwe(rated) or $ 200 per kwe (peak), the annual

production rate would have to be roughly 7 Mwe. This falls within the low range

of the Weingart/Weyss"quesstimate"and suggeststhat, if successful,the Mobil/

Tyco venture could return a much higher rate of return on investment since some

20 Mwe(peak) can be produced annually at ｾ lower total investment than $ 30 million

(according to their estimates) ( ).

Although this author feels strongly that with sufficient effort, mass production

techniquescan be developed to produce various types of photovoltaic arrays which

can be installed for costs below $ 1,000 per kwe(rated), this "feeling" is based

on rough estimates ( ) of what such a mass production technologywould look

like if fundamentalmaterials problems could be solved.

58

A much more "bullish" set of projections appear in the FEA Project

IndependenceBlueprint ( ). Two scenarios,one labeled "Business as

Usual" and one labeled "Accelerated" are shown in Table and plotted

in Fig. • The projectionsare consideredextremely "bullish" or

optomistic in that they imply that the competition for large scale production

of electrical energy will have very high costs indeed, in excessof

several thousanddollars per kWe Ｈｲｾｴ･､ＩＮ For example, with a systemcost

of $ 2000 per kwe (rated), it is estimatedthat the annual market might

be as high as 50 Gwe,

for new generatingcapacity in the United Statesprior to the events of

Fall, 1973.

59

Productionof Silicon - A Survey of Estimates

Country Date** Grade of Silicon Production (m tons/yr'f<* Mwe(R)/yr *

Global 1971 Semiconductor 103 (1)

Wacker (G. ) 1971 Semiconductor 300 (1)

USA 1977 SemiconductOl· 1500 (2)

USA 1980 Semiconductor 2038 (2)

USA 1985 Semiconductor 3300 (2)

USA 1990 Semiconductor 5560 (2)

USA 1995 Semiconductor 8625 (2)

USA 2000 Semiconductor 15,800 (2)

USA 1973 Single Crystal 750 (3)

USA 1974 Single Crystal 1250 (3)

USA 1973 Metallurgical 125,000 (4)

References

(1) Private Communicationwith Prof. Martin Wolf, 10 October, 1971

(2) Project Independence- Solar Energy Task Force Report, p. VII-A-3

(3) Ibid., p. VII-25

(4) LA. Lesk, "Large Scale Use of Single Crystal Silicon for Solar EnergyConversion", p. 419. Procedingsof the Symposiumon the Material ScienceAspects of Thin Film §'ySterns for Solar-EnergyConversion, NSF/RANN, May, 1974

** Actual production or (estimated) production

* Under the following assumptions: 0.25 cm thick cells with conversionefficiency of 0.10 under AMI illumination at 50 deg. C equilibrium celltemperature. Rated power (R) at 0.20 of peak power output under AMI conditions.

ｾｵ

MONTHLY COSTS OFAMORTIZING $ 1,000

ACCUMULATED COSTSOF AMORTIZIN G $ 1,000

·4000

0.10/YEAR----- --- ---------------- -- ------ ---

REF.: "EQUAL MONTHLY LOAN AMORTIZATION PAYMENTS"FINANCIAL PUBLISHING COMPANY,BOSTON, MASS.PUBLICATION No. 581 ,1969

10

70

80

60 t , l3000

0.10/YEAR ",

501 \,,"""

$ ,,'" I $",.""" O.OS/YEAR'"40 + \ /' ,,-'" t 2000",""" m","" a

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",."""--.---""",.

Ｋ ｾ Ｍ Ｍ ｜ ｾ +100020 \.

O.OS/YEAR

4030

--20

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o-I Io I I I I 0

TWO PROJECTIONS - U.S. SILICON AND PHOTOVOLTAICSILICON PRODUCTION, 1975 - 2000

a.ｾ

10 }J

102 }J

103,..

E.RALPH(1 )

-", """" ｾ ｅ A (2)""' ..................... -- "' .......

-- TOTAL SIC SILICON

-- PEPS SI LICON

- - - SOLAR CELL THICKNESS ( J.I )

103

10 , r I I I I I I 10°JJ1975 1980 1985 1990 1995 2000

102

104

METRIC TON S OF105+SEMICONDUCTOR

SILICON PER YEAR

t

bl

1989198519801975

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/I VARIOUS FORECASTS OF ACCUMU-I.LATED PEAK POWER GENERATION:-1 ..

I IN THE U.S. BY PHOTOVOLTAIC. .I/1 . CONVERSION. ..

.: I I. .' I,.1. .. .

.Ii

/.I..0.1

10

1.0

100

ACCUtv1ULATED PEAK POWER [MWe]MWe

1000

63

1GW. -+----.-- -+----1-'ANNUA'L MARKE ｾ V.s. ----l: ｾｖＮ SYSTEM COST - A GUESS

I :I 1I I

I100 MW ＭｴＭＭＭＭＫＭＭｾＭＮＮＮＮｌＭＭＭＭＭＭＭｴＭＭＭｴＭＭＭＭＭＫＭＭＭＭＭＭＭＱＱＭＭ

r'OMW , I, I, If- IUJ 'I::.::: ,a::« lMWｾ I'--'

I ,

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:::> I ,z I 'z I "ｾ I100kW

COST RANGE OFCURRENT RV.TECHNOLOGIES

•104 105 106

SYSTEM COST ($ I kWe ) ｾ

10 kW -t-.Ｍ Ｍ Ｍ Ｍ Ｍ Ｋ Ｍ Ｍ Ｍ Ｍ Ｋ Ｍ Ｍ Ｍ Ｍ Ｍ Ｋ Ｍ ｾ Ｍ Ｍ ｾ 5 PAC EC RAFT -II

I

COST RANGE OF iNEW RV. ITEC HNOLOGI.ES

1 kW 2 310 10

INSTALLED

).. F. Eldridge (

(' Businessas Usual"S enario)• "B Hish" prognosisof the

ｳ ｯ ｾ ｡ ｲ Energy Task ForeRe ort, PROJECT INDEPE DENCEBL EPRINT, FEA 1974p. VII-A-3

ｾ ｟ ibb ｟Ｂｾｾｾ･ｬＮ］ｲ｡ｴ･ｾｾｴｲｩｏＺＧII 1 73 total U.S. ｐ ｲ ｯ ､ ｵ ｾ ｴ ｩ ｯ ｮ

R te, Costs for Smal PVS sterns (E. Ralph, Re )

.ｾ .' . ｾ

" z i' .. t "

(J. Weingart land N. Weyss, ｉ ｉ ａ ｓ ａ ｾI

I

64

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65

Annual Market Vs. SystemsCosts (Photovoltaic) *

Total Average Power Capacity of Costs of PEPS SYSTEMSPEPS per Year (MWe) (1974 $ per kWe average)

Scenario 1 Scenario 2 Scenario3,Weingart/Weyss

3 6 .3 - 5 $ 7500

100 200 .5 - 7 $ 4500

500 4,000 1 - 12 $ 2500

2500 25,000 1 - 15 $ 2000

to to

10,000 50,000

Scenario1 1S the FEA "BusinessAs Usual" Scenario. *Scenario 2 is the FEA "AcceleratedSchedule" Scenario*Scenario 3 is the Weingart/Weyss ( ) questimateof market vs. costs for

photovoltaic solar energy conversionsystems.

* Federal Energy Administration, PROJECT ｉｎｄｅｐｅｎｄｾｲｲｃｅ BLL'EPRINT, Solar EnergyFinal Task Force Report, November, 1974 Page VII-A-3,4

66

INVESTMENT-PRODUCTION TABLE FOR PRODUCTION

OF PHOTOVOLTAIC CONVERSION ARRAYS ( ,Lindmayer)

YEAR AMOUNT INVESTED PRODUCTION Kwep/year '/(

1975 0.5 to 1.0 x 106 P 1001976 1.0 million 3.2P 3001977 1.0 " " 1,0001978 2.0 " " 3,4001979 4.0 " " 10,5001980 6.0 " " 34,0001981 11.0 " " 107,0001982 19.0 " " 320,0001983 42.0 " " 1,000,0001984 " 3,500,000

Total $ 88 million Cumulative 4,976,300

Table

'/( Peak kilowatt electric production under conditions ofAMI Insolation

ｾ

ｾ

..

PRODUCTION OF PHOTOVOLTAICSOLAR CONVERSION ARRAYS( kwe p ) AS A FUNCTION OF TIME.J.LlNDMAYER. REF.

1975

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200

100

$500/ kwe (1985)

$ 100 / kwep (199 5)

tASSUMED RANGE OF COSTSFOR COMPLETE PHOTOVOLTAICARRAYS BETWEEN 1985AND 1995

20199519901985

VARiOUS EST!MATES FOR T1-iE COST OF PHOTOVOLTAtCARRAYS AND DEPLOYED SYSTEMS AS A FUNCTION

19801975

4

1

2

3

- $ x 'tT/kwe AVERAGE OF TIME

Ｎ ｾ 1. --+ _

ｾ｜ - -

\,\ \. "\ :'\...

'\ ｜ ｾ"'\

\ "'\.

-"- ｾ ｾ COMPLETE SYSTEMｾＬ ｉｾｾ

" " , . ｾｾ"" ---....O"--::-H--------+---.-ｬ Ｍ Ｍ Ｍ Ｍ ｊ Ｍ Ｍ ｾ Ｍ Ｍ ｾ Ｍ Ｍ Ｍ Ｍ ｴ Ｍ Ｍ Ｍ Ｍ Ｍ ........... PV ARRAY __. ＭＭＭｉｾＭＭＭＭ

o1973

7

5

6

9

8

l ........ _.... ,JhQ4 l '!A&..

72

Land and Materials Considerations

By the year 2000 the LDC's will have a population of roughly six billion

people ( ). Supposethat the ultimate goal is to provide energy in the form

of synthetic fuels (perhapshydrogen) and electricity. Supposefurther that

human settlementswhich function well and which provide more than the basic

human necessitiesof decent nutrition, health and shelter can operateon a

total of 3 kw (1.5 kw fuel + 1.5 kw electricity).

If photovoltaicswere to provide half of this electical energy demand,

the area required would be quite large. Suppose, in an extreme case, that

on the average20 percentof the incoming solar radiation in the LDC's could

be convertedand delivered in the form of electrical energy, and that the

annualizedaveragedaily insolation is 5 kwh/m2 -day.

On the average, the area dedicatedper capita would be 24 m2 and the

entire aggregatearea would be:

6 X 109 people x 24 m/person

Perhpasas much as one third of this could be provided through rooftops

in low-rise settlements. The remaining 96,000 km 2 (slightly larger in area

than Austria) could in principle be provided through ground basedand floating

arrays.

The total power could he, on the average:

P = 9 TWe.

or 20 times the entire installed peak generatingcapacity of the United States

in 1975.

If the growth of electrical power generationsystemswere to increase

over the next four decadesat the previous rate (over the past three decades)

of 7 to 8 percentper year (doubling time of one decade), it would take four

decadesto achieve this. To achieve somethingof comparablescale in the

developing countrieswould take, in an optomistic view, at least a century.

73

If the installed cost of such systemsturned out to be only $ 500/kwe

(1975 dollars) the total cost of 9 TWe would be:

$ 4.5 trillion dollars.

Hence, if somethingon the order of one percentof the global GNP were

invested in such systems (assuming ｴ ｲ ｾ extreme caseof low cost and high

conversion efficiency) each year, the job could be done in a century and

presumablycould be done in three to four decadesif the rate of expenditure

were 3 percentper year. In the more likely caseof a net conversion

efficiency of ten percentand a system cost (installed) of $ 1000 per kwe,

it would require 12 percentof world GNP per year for 30 to 40 years or

3 percentper year for a century.

In the event that such systemscould be built with an averagedensity

of supportmaterials (steel and concrete) of perhaps10 kg per squaremeter,

the total materials requirements,excluding silicon, would be:

1.44 billion metric tons (steel and concrete).

If everything were steel, this would amount to approximately 5 percent

of projected USA steel production over the coming hundred years and perhaps

a percentor two of total world production. Silicon requirementswould be

at 5 kg per squaremeter:

.18 billion metric tons(silicon) (.010" thick silicon).

This would require, on the average, an annual production rate of

7.2 million metric tonns of silicon solar convertors. Since total world

production of semiconductorgrade silicon is roughly a few thousandmetric

tons per year today, a ten-fold expansionin production would be required

and would have to operateover a century to meet thesegoals.

Country 2Land Area (km ) Population (1974) Population (2000) Total Area Requiredfor PV Conversion

Fraction of totalland area

""-..Jｾ

* SemiconductorGrade

TABLE 4 - MATERIAL CANDIDATES AVAILABILITY

•fｾＮ! .

0.14(14)

2.3(12)

1 4(1l)

2.8(12) r -.,Ji

2.4(15) t· (J'1i

0.1(15) Iti.

fｾｉ ..•l.'"i:

t

l.'lrlｾＮ

ｾ•,ｾｾｬ

t

J

*(7)

------1-·X ｲｵｲｦｴｾﾷ ｩｮＯｈｬｾ

."",,- "', ｾ ｾ (T 1)

99.7 I 5.0(12)

JOPPB11 O. x 103(8 ) I' U10 ! H)

19.4 x 106(5) ｮ Ｎ Ｑ ｦ ｾ Ｉ

(2) I (2) I ［ＮｾＧＬ205. x 103(4) 850. x 103(4) 7. ( ,

91. x 106(6) 1407. x 106(6)\ ［ Ａ ｜ ｉ Ｚ ｾ ｾ ｾ

2.7 )( 103(8)

1.43 x 106(5)

(7) Ey plrctro)ysis.(8) ｰ ｲ ｩ ｖ Ｎ Ｉ ｩ Ｈ ｾ cO:lInJunic.Jtion from tir. r. Chin ibid.(9) Private cr"r.I:lIJni cation from ;1'5. r; Green<;poon ibid.(10) Pt'ivate c,."mr,tll1 i (,1 ti on for MI'. L. '!oore, i bi d.(11) 200. x ＱｾＭＴ ell thick Clnd 20:: f'ff •. iercy.(12) 20 )( Icr err, t.hief: and 7"1, effici dCY.

( 13 ｾ I'la ｾ｡ et ,,1 ｾ ｎＺｾｆ Conference,Cher",' Hi 11 J tJew Jersey(14, 10 em £'PCk.(15) 10 x 10- em t.hick.

ｬ ｊ Ｌ ｓ Ｂ Ｍ ｾ Ｍ ｗ Ｖ ｲ ｔ ､ Ｍ Ｍ ｔ Ｍ Ｍ -.Reserves(1) P-esprve:; {1 ) ICnst, I Kqm'--r--I-.-- --.- - _. __.._. . ._ ._. _ .

Element I U.$: ( 1) I Wo r1d__ ＮｾＡＮＮ＿ｾｵｾｾｾＢｮﾷ Prod'Jction(l)

--------. ---1---.--

750. (1973)(3)5i I :J250 (1974)(3)

Cd 3.0 x 103 (4) 17.1 x 103(4)

cu I 1.83 x 106(6) 8.05 x 106(6)

SSi

I ibid

Ga O.3(5( r1.0(5)

As '9 '03(9) I 52. x 103(9)I • x I

Cd ibid

Te 1. x 102(10) 11.92 x 102(10)

Cu ibid

In

S.e 3.4 x 102(10) 11.02 x 103(10)

A11 ｜Ｇｉｾｩ ｧｾｬｴｳ it r'e ｲｲｾＺ It i c tons (1,000 K'Jr.l/.[:;scntially ｵ Ｇ Ｑ Ｑ ｪ Ｇ ｾ Ｑ Ｂ ｩ ｴ Ｌ ｾ ､ Ｎ

Chemistr.)' ar:c1 Enqin"ering ｎ Ａ Ｚ Ｇ ｜ ｾ ｳ Ｌ July 23, 1973Private r.Qll';11unicatio'1 from Hr. D. Hagul', Bureau ofMines, Division 0f Kon-Ferrous Metals. U.S. Depart-ment of the Interior.U. S. t'1inenl ReO-ourees,ｇ｣ｯｬＨＩｦｾｩ｣｡Ｑ SurveyProfessionalPaper 820, 1973, Departmentof ｉ ｾ ｴ ･ ｲ ｩ ｯ ｲPrivate CommunicJtion from Hr. Schroc«;Jer,;bid

Cell

CdS/tuAS'.

Single Crystal S1

Thin Fflm Sf

CdTe

CuIn 5eZ

(l)(2)(3)(4 )

(5)

(6)

7.5 x 103(10) 13.1. )( 101(10) 11';.,1.,(10)

I5.3 x W?(9) \31.8 x 102(9) ?l5. :0)

L _. ._ 1 .__1______! ｟ ｌ ｾ ｾ Ｌ Ｌ Ｍ Ｍ Ｌ Ｍ Ｌ Ｚ Ｓ Ｈ ｔ ｾ Ｉ L'" '.' 10'(1O! 10' '.':.__. .L.- __J

IGaAs

<ｾ......,'v

""

76

A PRELIMINARY SURVEY OF EXPERIMENTAL ANDCOMMERCIAL TERRESTRIAL APPLICATIONS OFPHOTOVOLTAIC SOLAR ENERGY CONVERSION

77

INTRODUCTION

Since the invention of the silicon solar cell in 1955, there have

been perhapsa hundred individual terrestrial ｾ ｰ ｰ ｬ ｩ ｣ ｡ ｴ ｩ ｯ ｮ ｳ of photovoltaic

solar energy conversionsystems, ranging from scientific experimentsto

commercial use by industry and ｧ ｯ ｶ ｾ ｮ ｭ ･ ｮ ｴ Ｎ Installationsfrom a few watts

to over a kilowatt peak power have been made in Africa, South America,

Mexico, the United States,Canada,Europe, Japanand SoutheastAsia, and

the Middle East. These have provided power for lighthouse navigational

and warning lights, radio, microwave and television relay stations, aids

to navigation on off-shore oil platforms, weathermonitoring stations,

remote educationaltelevision sets, highway emergencycall boxes,

aircraft warning lights at airports, and remote communicationsstations

for forest management. The presentannual commercial market for

photovoltaic arrays is perhaps10 kwe(peak), divided roughly equally

among Japanese,American and European (French, British and W. German)

manufacturers.

A limited literature survey was made to develop a preliminary

sketch of the pattern of previous and current terrestrial applications

of photovoltaic conversionsystems. Using the results of this survey,

a follow-up survey employing telex, mail and telephonecommunications

has been initiated to obtain detailedwritten and graphic information

about various installationsand availableproducts.

In addition to reporting on applicationsin operationor being

planned, a recent report ( by Spectrolab, Inc. to the NASA/Lewis

ResearchCenter, examining near-termpotential markets, was also reviewed

Some of the systemsproposedin this report may be of special interest

in LDC's. A specific example is a proposedphotovoltaic-poweredsystem

for irrigation and provision of potablewater (through the incorporation

of a solar powered ultraviolet water purification device) for a small

community.

The resultsof this survey are presentedin Appendix Al in a set of

tables and in a set of more detailed single page descriptionsof various

example systems. The latter have been useful in defining further information

neededto provide a fairly comprehensivedescriptionof a specific system.

Finally, several specific systems, including the solar powered remote educa-

tional television system under developmentin Nigeria and the Spectrolab

proposedsolar-poweredwater irrigation, storageand potable water supply-

system, are discussedin some detail.

78

This sectionof the report will be updated, expandedand refined

as information from various sources (users,manufacturersand others)

is received.

79

TERRESTRIAL APLICATIONS OF PHOTOVOLTAIC SYSTEMS

The categoriesof application of photovoltaic systemsfor terrestrial

use include scientific testb ana demonstrations,quasicommercialor

prototype commercial applications, fUlly commercial applications, and

(for the future), potential ｰ ｨ ｯ ｴ ｯ ｶ ｯ ｾ ｴ ｡ ｩ ｣ systemmarket areas.

Experimentalor demonstrationuses of solar cells began in 1955 when

Bell Laboratoriesand the Bell TelephoneCompany installed a solar-powered

rural telephonecarrier system in Americus, Georgia. The system was

operatedfor about six months, as a technical demonstrationand publicity

effort. In 1973, combined photovoltaic (CdS) and thermal collectors were

integratedinto a laboratory/houseat the University of Delware ( ) to

explore the nature of residentialsolar electric/thermalsystemsconnected

to a local electric utility grid. At the California Institute of Technology,

scientists ) from the Geology Departmentare using surplus spacecraft

solar panels (from Ranger and Mariner spacecraft),suitably modified for

protection againstweather, to power remote scientific geological stations

in California and Mexico, and the Mitre Corporation (Mclean, Virginia) is

developing a one kilowatt solar electric/hydrogensystem ( ) to demonstrate

the combined use of solar generatedelectricity and electrolytic hydrogen

as the secondaryenergy carrier. All of ｴ ｨ ｾ ｳ ･ applicationshave been

largely scientific in nature, ｷ ｩ ｴ ｨ ｾ ｵ ｴ attempting to explore near term

markets for photovoltaic applicationsalthough the work at the University

of Delawarewill eventually lead to an evaluationof combined photovoltaic/

thermal solar collectors for building applications

Other experimentalsystemshave been installed in the Chilean Desert

as a joint University of Chile/RTC (France) project, in Iran (at Pahlavi

University in Shiraz), France, Africa, the Soviet Union, India, Japan,

Britain and Germany.

Quasicommercialor commercial prototype systemsare those in which

the initial installation was made in order to determine the operating

economicsof the solar system and to make a comparisonwith other available

energy systems. Such applicationshave generally been made in situations

where there has been a need for remote power in the one to one hundred

watt range and where replacementof batteries, transportationof fuel or

80

remote power lines were very expensive. Such applicationsinclude remote

radio beacons,radio, television and microwave boosterand repeater

stations, warning and navigational lighting on offshore oil platforms,

and so forth. A number of installationsmade on a prototype basis have

led to continued commercial installaLions basedon successfuloperation

of the prototype.

Examples include the first remvte solar cell application in Japan,

to provide power for a 150 MHz VHF repeaterstation on Mt. Shinobu (

and installationsby the California Dept. of Forestry of Motorola solar

cell powered telecommunicationsequipment in the late 1960's. In both

cases, there have been later commercial installationsresulting from

economic and technical successof the initial installations.

81

Commercial (marketplace) Installations

In 1961, Kobayashi ( ) reported that is was more economic, on

a life-cycle cost basis, to provide remote power at levels up to fifty

watts by a solar cell/storagebattery combination costing $ 130/peak

watt than to run a power line 1 km. (Figure ). Today Spectrolab, Inc.

has sold over a hundred systems for remote power for navigational

and warning lights on off-shore oil rigs in the United ｓ ｴ ｡ ｴ ･ ｳ ｾ several

statesin the USA including California, Nevada and Oregon are purchasing

photovoltaic power systemsfor remote radio repeaterstationsand other

similar ｡ ｰ ｰ ｬ ｩ ｣ ｡ ｴ ｩ ｯ ｮ ｳ ｾ sailboatowners are purchasingsolar arrays to

keep batterieschargedduring long voyages and the French are providing

solar television sets in Nigeria ( ) for educationaltelevision for

the populace. Small solar-poweredradio were marketedby Motorola in

the early 60's and, at the extreme end of the luxury market, a German

company has recently introduced a solar powered (trickle chargedbattery)

electronic cigarette lighter for several hundred dollars: As mentioned

earlier, the total world market for diverse commercial and spacecraft

applicationsis roughly 50 kwe(peak) per year and, at presentprices for

photovoltaic arrays, expectedto grow to perhapsthree times that within

three years ( ).

Commercial systemsare consideredby us as those which are produced

as a regular product line by a company, and commercial applications, in

our ｴ ｾ ｲ ｭ ｳ Ｌ are those in which such products have been purchasedby some

organizationbecausethe solar option was the most economical on an

annualizedcost basis. The current commercial market for terrestrial

photovoltaic systemscould be characterizedas one in which some

combination of high reliability, low or no maintanence,zero fuel

requirements,and noiselessoperation, at power levels below one kwe

(peak), justify, on an economic basis, the use of photovoltaic systems.

These "advantages'·of pl:otovoltaic systemscan certainly be compe"l-

satedby transportation(horseback,foot, jeep, helicopter, etc.)for

fueling and maintanencepurposesto remote locations and batteriescan

be purchasedand installed each year. Power lines can be laid and noise

insulation installed. Each of these has some specific cost for a given

application and a geographiclocation. Hence, the characteristicsof

PV systemstranslatedirectly into economic advantages. (An economist

would say that in these casesthe market is operating normally).

82

Commercial systems (discussedin section , are available from four

manufacturersin the USA, two in Japan, and one each in Germany, France

and England. Manufacturerswill provide either individual silicon solar

cell modules, appropriatelyencapsulatedin rugged supports,or complete

systemsincluding batteriesand power conditioning equipment. All of

the presentcommercial applicationsuse arrays fabricatedby one of these

9 manufacturers.

83

Commercial Applications - Examples

The National Aeronauticsand SpaceAdministration (NASA) Lewis

ResearchCenter ancl the National Oceanic and Atmospheric Administration

(NOAA) are cooperatingon a project l ) to design, fabricate and

install a number of solar power systemsfor remote atmosphericmonitoring

stations. Two installations,one in Virginia (Sterling) and one in

California (Mammoth Mountain) were made in 1973 and further installations

are expected. As a precommercialapplication, solar arrays have been

fabricated by NASA/Lewis using solar cells purchasedfrom a domestic

supplier( ). The solar arrays are made up of modules each

containing 48 (six by eight) circular silicon solar cells. (3 watts

AM1). The total array at each installation contains 20 modules, for

a peak power of 60 watts. The arrays are encapsulatedin PEP sheets.

In 1973 the Tidelands Signal Corporationof Houston, Texas

fabricated a complete aid-to-navigationwarning light system, including

silicon solar arrays fabricated by Solar Power Corporation (Massachusetts)

and installed the system on an offshore oil platform in the Texas Gulf

Coast.

The lighting system on the referencedoil platform consistsof

one 2-mile fog signal and four 5-mile lamps. Energy consumptionis

about 25 am-hour/dayx 12 volts = 300 whe/day. PreViously this lighting

systemwas powered by 40 1.2 volt. 3300 amp-hr primary batteries. The

total weight was 2,000 lbs and thesewere replacedannually. The solar

generatorsystem incorporates80 photovoltaic modules (1.5 watts peak

under AMl illumination, 25 deg.C) into an array with overall dimensions

4 x 5 feet (1.22 x 1.52 m). The referenceimplies a retail cost of

roughly $ 20/peak watt and indicates that at such prices for a terrestrial

array (sealed, ready to install), such arrays begin to compete with

primary and secondarybatteriesin markets traditionnally servedby this

hardware. The ref. claims that "solar cell/secondarybattery systems

clearly competeon an economic basiswith heavy duty primary batteries"

(presumablyon a life-cycle cost basis, although the specific numerical

details are not discussed).

84

Solar Powered EducationalTelevision Sets in Nigeria

Becausethis particular example is one of the very few documented

applicationsto have actually been made in an LDC environment, I have

translateda portion of the paper by ) into Enqlish.

The synopsis follows:

- The EducationalTelevision ｾ ［ ｹ ｳ ｴ ･ ｭ of Nigeria (TVSN - Tedevision

Scolaire du Niger) was createdin 1966 in order to upgrade the

inadequatelevel of primary education in the country. Since 1966,

some 800 studentsin 22 classeshave received instruction via

television broadcastfrom the production center in Naimey (through

use of solar powered television). As a result of the encouraging

results of this experiment, the Nigerian governmenthas decided to

put in place, progressively, a network of (solar powered) ｴ ･ ｬ ･ ｶ ｩ ｳ ｾ ｯ ｮ

setswhich, within ten years, would reach eighty percentof the

population with educationalprograms.

The programsof the Nigerian educationaltelevision system are

primarily intended for schools located in regions without electricity.

Reception is assuredthrough the design of television sets especially

constructedto operatein very cold and very hot climates. These sets

are transitorized,designedfor a wavelengthof 61 cm, and are designed

to operateon a continuoussource of electricity at 34 volts plus or

minus fifteen percent. Their consumptionis 35 watts. Currently these

sets are powered by batterieswith a life of about 2,000 hours.

This solution, the most widely used in actual practise, is quite

costly. An hour of television costs roughly 1.38 francs. In order to

develop a more economical sourceof energy, the technical servicesof

TVSN and the Office of Solar Energy (NIAMEY) installed, in 1968, an

experimentalsolar panel to power the television of a school near Niamey.

This experimentdemonstratedthat it is practical to provide solar

powered television in NIAMEY during the entire school year (October to

June).

An applicationsstudy has been carried out by the Engineering

Service of the ORTF and six new installationshave been made in 1972.

85

Considerationsfor Deployment of PhotovoltaicSystemsin LDC's

The attractivenessof a photovoltaic system application in an

LDC will dependon the economic significanceof that application to

those who have to pay for and maintajn it. In some casesthis may be

some agency of the government,or an international agency (AID, UNEP,

World Bank, etc.); in others it wi-l be the local inhabitants

themselves. It is the author's conviction that a fairly sophisticated

analysis of the value of various energy-relatedor energy-derived

(specifically electrical energy) servicesin various cultural and

geographicenvironmentsis required before a useful assessmentof the

potential market for solar power systemscan be made, (unless the cost

of these systemsdrops to the point it is the cheapestalternative

available for large scale power generation). The nature and size of

various LDC markets will depend, of course, on the delivered cost of

the PV systemsas well as on the value of electrically-derivedservices.

Part of the required analysis would be an eeconomicassessmentof the

value associatedwith the following featuresof PV systems:

1) High reliability,

2) Low maintenancerequirements,

3) Zero fuel requirements,

4) Intermittant output without storage,continuouswith storage,

5) Modularity (when one piece of the system goes out, the rest can

continue to function; not true with generators)

86

Reliability

Photovoltaic arrays have no moving parts and the basic physical

mechanismwhich accountsfor the photovoltaic property has a lifetime

measuredin thousandsof years for silicon. (I.e., it is basically

related to the rate at which impurity atoms, which form the pn junction,

diffuse through the lattice, ､ ･ ｧ ｲ ｡ ､ ｾ ｮ ｧ the junction). Techniqueshave

been developedto encapsulatesilicon solar cells in a clear silicone

material which provides excellent shock isolation and protection from

environmentaleffects.

Such reliability may be of crucial importance if such systems,

when they appear economicallyattractive, are to be diffused rapidly

and widely. People are slow to put total reliance on innovations until

a lonq period of test .and experiencehas gone by.

Low maintenancerequirements

This is not the same as high reliability, although the two are

sometimesconfused. An automobile engine is a highly reliable device,

providing a specific level of maintenanceis sustained. The relationship

betweenmaintenanceschedules(and costs) and the reliability of various

ｴ ｙ ｾ ･ ｳ of machinary is r;enerally well ｫ ｮ ｾ ｷ ｮ in industrializedcountries.

In the case cf suitably designedsolar cell arrays. the level of

maintenancerequired to provide very high reliability (on the order of

one failure per ten years of operation) is probably low and

inexpensive. It primarily involves protection of the transparentsurfaces

from extreme abrasonand periodic cleaning of both the surface and perhaps

the electrical connections: The author expects that modules CQuld be

developedfor which maintenancewould consist only oi occasionalcleanino

at most. A number of photovoltaic systemshave operatedfor close to a

decadewith NO cleaning and with NO OBSERVABLE DEGRADATION in relatively

dirty industrial atmospheres(the Cleveland airport, for example).

87

Low maintenancerequirementsmeans little labor required for upkeep

(although labor is generally cheap in the LDC's). The fact that

unsophisticatedmaintenanceprocedures,requiring minimal equipment

(perhapssoap, water and a rag) can be used means no supportive infra-

structure for maintenanceand repair, no specializedtraining of maintenance

personnel, no special tools, etc. (Compare this with the minimum tools,

training and accessto spareparts required ｦ ｾ ｲ the simplest internal

combustion engine/generatorcombinatLonl.

Zero Fuel Requirements

This may have special significance in some LDC's. This aspectof

PV systemsmeans that the users are insulatedfrom variations in the price

and availability of fuels. The local delivered price of fuel could

include local costs not normally included in such calculations, such as

graft and corruption by these controlling the distribution infrastructure.

(More about these cultural issueslater). With sufficient electrical

storage, the PV systemscould then be more reliable than many other

alternatives, in which transportationof fuel may be uncertain.

Modularity

The modular nature of PV systemspermits the users to gain experience

with a relatively small investment. This is a crucial aspectof rapid

diffusion of an innovation (Rogers l. When large investmentsin

innovations are required, they may never be adapteddue to the lack of

opportunity to "test them out" at an acceptablelevel of financial risk.

Systemscan grow as the affluence of the local community grows, and system

elementscould be designedto permit the developmentof local "grids" as

neighboring systemsgrow and eventually become contiguous. Loads can grow

with supply, meaning essentiallyfull amortivation of the investment.

Finally, a modular power systemmeans that one or a few PV elementscan

fail and the system can continue to operate. Replacementscan be obtained

at the most convenientand least expensivetime (such as when a government

team makes its annual visit or some such occasion)•

REFERENCES

88

TerrestrialApplications of

Photovoltaic Solar Energy ConversionSystems

Al A. Forestieri, "PhotovoltaicTerrestrial Applications"Proceedingsof the PHOTOVOLTAIC CONVERSION OF SOLAR ENERGYFOR TERRESTRIAL APPLICATIONS Workshop October, 1973.National Science ｆ ｯ ｵ ｮ ､ ｡ ｴ ｩ ｯ ｮ Ｏ ｾ Ｇ Report NSF-RA-N-74-013

A2 A. 1. Rosenblatt, "Energy Crisis Spurs Developmentof PhotovoltaicPower sources", Electronics (GB), April 4, 1974, p. 99ff

A3 S. Polgar, "Alimentation de Televiseurspar Photopilespour laTelevision Scolaire du Niger", Proceedingsof the 1973 InternationalSolar Energy Society Conference,Paris. p. 553 (Trans.: PoweringTelevision Sets by Solar Cells for Nigerian EducationalTelevision)

A4 B. Dalibot, "GenerateursSolairespour Applications Terrestres"Proceedingsof the 1973 InternationalSolar Energy Society Conference,Paris, p. 565

AS B. Kelly et al, "Investigationof PhotovoltaicApplications",Proceedingsof the InternationalSolar Energy Society Conference,Paris.

A6 M. Kobayashi, "Utilization of Silicon Solar Batteries"Proceedingsof the ConferenceNEW SOURCES OF ENERGY, p. S-ll,Volume 4 (Solar Energy: I). August, 1961, United Nations.

A7 G. Pearson, "Applications of PhotovoltaicCells in Communications",Proceedingsof the ConferenceNEW SOURCES OF ENERGY, Vol. IV,P. 236. August, 1961, United Nations.

A8 M. Prince,ConversionSOURCES OF

"Latest Developmentsin the Field of Photovoltaicof Solar Energy", Proceedignsof the ConferenceNEWENERGY, Vol. IV, p. 242.

A9 J. Ravin, "Study TerrestrialApplications of Solar Cell Poweredsystems", Report preparedfor the NASA Lewis ResearchCenter underContract NAS 3-16828. NASA Report number NAS-CR-134512. September,1973.

A10 R. Yasui, Jet PropulsionLaboratory, Caltech (Private communication)

All

A12 E. Costoque & H. Vivian, "Solar Energy RechargeablePower system",internal document, CaltechJet Propulsion Laboratory,June 15, 1969. JPL DOcument No. 650-81.

89

Attachment Al

SUMMARY OF TERRESTRIAL APPLICATION OF

PHOTOVOLTAIC SOLAR ENERGY CONVERSION

,

SUMMARY DESCRIPTION OF SOME SELECTED EXAMPLES OF TERRESTRIAL APPLICATIONSOF PHOTOVOLTAIC SOLAR ENERGY CONVERSION SYSTEMS (1955 to 1975)

DATE LOCATION APPLICATION ARHAY OTHER SYSTEM COSTS REFERENCEINSTALLED ｄ ｅ ｓ ｃ ｒ ｉ ｐ ｔ ｉ ｏ ｾ COMPONENTS

i ＨｒｾｍｏｖｾｄＩIi i;

-- -- --- .-..._.._.. -_._... ._- --_._. -- - _. -- ｾ --------- - . -- .. --. -.- ._.. -1955 ! Americus, Ga. Power for runll 22 vnc, 1n N, 22 VDC, 15 AH (N/A) A7

'1956) i (USA) telephonecarrier Silic0n (Pel! ｾ ｩ Ｍ ｃ ､ battery!ｾｹｳｴ･ｭ ｌｊｨｾＧ

! jI1

: Jt)fl ! Chilean desert ｅ ｸ ＿ ･ ｲ ｩ ｭ ｾ ｮ ｴ ｡ ｬ 3wall 3.3 \1:1(", 27 7', , A4remote power system 8 ｾ l" I S1 (RTC

! ｾｲ＼ｬｮ｣｣Ｉ

ｾI

ｾ l30/vlatt for1 10 1:;9-1960 JAPAN (Eight 10 W or 25W ｗ･ｾｴｴｮｧ '2 VDC, 12 W ｾＱＭｃｲ ｨＮＧｴＫＭＢｾｲｩ･ｳ A6i ll")cations) house lighthouse I ｾｩ lic:on, . secd13[1 pC'mplete ｳ ｹ ｳ ｴ ｾ ｭ

! w"1rning lights 1:_ acry11':: reR.!I -, 195R-1qr O JAPAN (six ｾ ｲ Ｇ r r adi 0 rnreater 12\7,60'1, or ｾ l30!vlatt for AfiI . '- • -

Jocatjons) stations (rr:>Mote) l3() V, 3 to 70 c0mplete system! Watts, Silicon Ｈ ｾ--- .__.

('"1968 St. Girons, Remote radio ｢ ｾ ｡ ｣ ｯ ｮ 50 l"!, 24 ｾ Ａ Si_ Ail:(1971)

,Bordeaux (r.>eri"l navicration)i (RTr.) \ i

I

(FRANCE)-' I

i

12 W radio relay 5i, RTC ｾｹｮ･ ｾi

! lq71 l FRANCE A4i ; (Paris?)I

station at the ｆ ｲ ･ ｮ ｾ ｨ BPX-70 ｭ Ｌ Ｂ Ｌ ､ ｵ Ｑ ｾI ｎｾｴＧｬ Center for ｴ ｨ ｾI

i ｓｴｾ､ｹ of Telecommun Ii

icati0ns--- ---,

11972 Lake Erie,Ohio Cleveland Coast 5i ·dth FEP $ l5/watt(cell ) Al!

,(USA) Guard Station(tele covers. 1.0 \"1 $ 40/watt

I com"Tlunications) rncdules (NASA/ (system)iI

I Lewis ResearchI

I i Center)

ｾ Ｙ Ｗ Ｓ Ne\'lark,DelawarE Exrerimcntal solar CdS experiment. (complex,see AllI (USA) powered/heatedlab cells data sheet)lI ("So l ar Oneil)iI

SUMMARY DESCRIPTION OF SELECTED EXAMPLES: PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS FOR TERRESTRIAL APPLICATIONS

: Ｈｍｾ､ｩｮ･ airport) I i

ｾａｔｅ ｾ location rpPLICATION ARRAY OTHER SYSTEM COSTS REFERENCE(S)INSTALLED I DESCRIPTION COMPONENTS(REMOVED) iI I

.. _. .::=====;f=- Ｚ］ｾＮＺＮＺ］ＮＺＺ｟ＭＺＺ］Ｚ］ＺＮＺＭＭＮＺ］ＺＮＺＺ］ＭＭＺＮＺ -::: :==--=.:..::-...:..:.::::...._- ... _- ..' ..... ........ ....Silicon(BPX 47) : A4

r solar arrays ! .

"t (RTC France) I II

A4A2

'I

1970's USA Lighting for warning Spectrolabl2W

?and navigation on i l2V, 6 ,.: SiElse,·There ... ,. . • approx. 100 oil rigs array, scaledin Gulf of Mexico : in cle3.r si1 i ｣ｯｲＮＱＨｾ

1970'sIi SOUTH AMERICA Television siqnal i eight 12 W

boosterstations modulesA4

: A2

. 88 A2

!ｾi;

. AS A2????

, ------r, I, I; Centralab S i 'i sea.ledarrays

for???!ｔｎｄｉｾ ｐｾｲｮｯｴｾ ｾｏｗｑｲ

J ｾ

ＭＭＭＭＭＭＭＭｾｬｩ villagesI ,

1973? ! TEXAS GULF Aids to. Navigation Solar POTt,er ;Batteries,lights $ 20/\tlatt(P) : 1\5 .'COAST(USA) Equipment(lights1) Corp. Si cell power condit. . I

, on Offshore Oil modules , l20W: ,:: Platform peak power i ' : I

1972 iNIGERIA Remote television RTC France, BPXj Battery,TV, : $ 100/watt(P) A4 II for education, 6 -47 Si modules I diode, antennai for array i; systemsoperational (8 ,,,atts)' i II NOTE: Referel'1ceA4 is primarily c journalistic a( count and menti ems some exampl<s, such

as the Indian village poweI systems, essenially as hearsa'.This example is beingincluded until the sourcecf the quote men ioning it proviaesmore detail! or disavowsit. (Letter sent to source of quote).

'--------lJ----.----------I--. --_..... -. .___ -_. ...I-.. --JL- ...1.. __

DATEINSTALLED

(REMOVED)

1970's?Current

SUMMARY DESCRIPTION OF SELECTED EXAMPLES: PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS FOR TERRESTRIAL APPLICATIONS.---..------r--.------ -···---···t---- .-----./-- -----1:ARRAY OTHER SYSTEM

LOCATION I APPLICATION DESCRIPTION ,COMPONENTS ,COSTS , REFERENCES

I , , I IｾＭＧＭＭＭＭＭＭＭＢＭＧＭＭＭｲＢＧＢ ... .!. .. ....." t· ..- .--- ..-----------..1=--

ｉｃｾｾｾｾｾＺｾＺＮＭＺａＭ ｩＴＰｳｾＺｴｬｯｮＬ radiolsilieon, lOW I b:ttery.::er1$ ｾＲｾＺＭＭｾｯｲＭＭｾＺＭ : ＭｾＴ: : repeaternetwork ' conditioning . W completeI ! system fromI Solarex

1966 l!JAPAN Lighthouse, lights silicon,Ii for x:avj gation and 1156 watts:: , ｾｬ｡ｲｮＱｮｧI:

: A12

1966 (?)

ｒ ｂ ｾ ｾ ｡ ｂ \' Fairbanks, P.emote te1ec0mrnuni silicon, 7 N ,13.6 V battery,Alaska Ｈ ｕ ｓ ｾ Ｉ cations(cnvironmen ,18 watt trans-

La] data station) !mitter

1\12l.CＺｾ

A121968\:ca1ifo:nia(US1\):R:-mote ｣ ｯ ｾ ｭ ｵ ｮ ｩ ｣ ｡ Ｍ silicon, 4 W Ni-Cd batteryＺ ｭ ｯ ｵ ｮ ｴ ｡ ｾ ｮ ｳ 't1ons ･ ｯ ｵ ｾ ｰ ｭ ･ ｮ ｴ

Ii : I

,I I ' -

II:

l

I

J_. I I -"

93

Attachment A2

DETAILED DATA SHEETS FOR JnNDIVIDUAL

PHOTOVOLTAIC SOLAR ENFRGY CONVERSION

APPLICATIONS

94PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF ｐｉｉｏｔｏｖｏｌｔｾｉｃSOLAR ENERGY CONVERSION SYSTEMS. (By J. ｶ ｬ ･ ｩ ｮ ｾ ｡ ｲ ｴ for the NationalAcademy of SciencesAd Hoc Committee on Enerey Technologiesfor ｌ ｄ ｃ ｾ

APPLICATION,STATUS

ISOlar Water Pump ｓｹｾｴ｣ｭ (Conceptual); Proposedforuse j n LDC 's

ｓ ｙ ｓ ｔ ｅ ｲ ｾ

DESCRIPTIONArray Type:Size:229 x 183 cmt----------I

12,90 Volts DC(peak)* ')0 & 12

:>,2.1 Current II

216 Power (watts), r: Ｚｾｲ

Supplier:

Cost Ｈ Ｄ Ｏ ｋ ｷ ･ ｄ ･ ｡ ｾ Ｉ $ 4Fno.

Other Components

Controllerl,'ater leve1 sensorMotor/water pumpｗｾｴ･ｲ ｾｯｬ､ｩｮｲ tankWRt8r purifier(ultraviolet)

10 ｾ Ｘ ｬ ｬ ｯ ｮ ｳ Ｏ ｭ ｩ ｮ ｵ ｴ ･ from aver.rlepth of 6 meters averageexpected flow rate.

LOCATION, DA'l'EOF DEPLOYHENT

PARTICIPATINGORGANIZATIONS

COMMENTS

Conceptu2.1,proposed ｾ ｾ ｯ ｲ LDC' s for irrigation andhuman water consumptinn/bathj.ng

Ｗ ｨ ･ Ｇ ｾ Ｌ ｴ ｯ ｲ ｲ ｴ ｧ ･ Ｂ is acccr.plishedby storar;e of \'laterso all available solar ･ ｮ ･ ｲ ｾ ｹ can be used.

SYSTEM DESCRIPTION/PERFORMANCE(Taken from ｾ ･ ｦ ･ ｲ ･ ｮ ｣ ･ indicated below

"The syf>tem consists of ;"in electric !"'1c;tor opernting on direct currenin conjunction with a solar power supply to diive a pump for irriga-tion in remote areas and underdevelopedcountries. The pumping svsteis desiGnedto operatewhere the ｷ ｾ ｴ ･ ｲ tahle is relatively ｨ ｩ ｾ ｨ Ｎ At10 ｾ ｡ ｬ ｬ ｯ ｮ ｳ per minute averagenumninr for 10 hours per day, thesystemwill deliver approxirratelV ｏ Ｎ ｌ ｪ ｊ ｾ ｩ ｮ ｣ ｾ ･ ｳ (1.11 em) of waterover one-half acre eV0PV da:.,. These are the soecificationsto whichthe solar water Dump ｳｹｳｴ･ｾ was ､ ･ ｳ ｩ ｾ ｮ ･ ､ Ｎ

REFERENCE

J. ｒ ｡ ｶ ｩ ｮ ｾ "Sturtv Terrestrial ａ ｯ ｰ ｬ ｩ ｣ ｾ ｴ ｩ ｯ ｮ ｳ of Solnr Cell PoweredSvstems"

95PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. ｗ ･ ｩ ｮ ･ ｡ ｾ ｴ for the NationalAcademy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

ａ ｲ ｲ ｌ ｉ ｃ ａ ｔ ｉ ｣ ｲ ｾ ,STATUS

lu.S. Forest Service - Remote mountaintop radioTransmitters (in currant use)

SYSTEMDESCRIPTION

Array Type: SiSize: 40 ｷ ｡ ｴ ｴ ｳ Ｈ ｓ ｯ ｬ ｡ ｲ ｾ ｸ Ｉt--------....&

Volts DC(peak)*

Current "40 Power (watts)

Supplier: Solarex

Other Components

Lead acid batteriesCharqe regulators

Cost ($/Kweoeak) $ 1200/40watt(p) system = 30 K/Kwe(P)

LOCATION, DATE current use ,OF DEPLOYMEWr

PARTICIPATINGORGANIZATIOm:;

COMMENTS

US Forest Service (Dept. of the Interior)

Details hcinry ｲ ｇ ｱ ｵ ･ ｳ ｴ ･ ｾ froM U.S. Forest Service

SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

Basic systemby Solarex includes 40 ｷ ｾ ｴ ｴ silicon solar cellarray, lead acid batteriesand charqe regulators and sells for$ 1200.

REFERENCEA. Rosenblatt, "Energy Crisis ｓ ｮ ｵ ｲ ｾ DevelopmentofPhotovoltaic Power Sources", Electronics (G.B.), April 4,1974, p. 99ff

96i

PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAIC ISOLAR ENERGY CONVERSION ｓｙｓｾｅｍｓＮ (By J. ｗ ｾ ｩ ｮ ｧ ｡ ｲ ｴ for the National"Academy of SciencesAd Hoc Committee on Energy Technologies for LDC0

ArrLICATIOtJ,STATUS

Demonstrationsolar cell powered weather station,Operational (1972)

SYSTEf-1DESCRIPTION

Array Type: SiliconSize:

Other Components

1.0

Volts DC(peak)*

Current "

Power (watts)

Each monule

Supplier: ?

Cost ($/Kweneak

) $ 15,000 (cells alone), 40,000/module

LOCATION, DA'l'E Cleveland Coast Guard Station, Lake trie (Ohio,USA)OF DEPLOYMENT 1972

PARTICIPATINGORGANIZATIONS

COMMENTS

NASA/Lewis ResearchCenter, Cleveland Cnast Guard

Module costs reflect ｩ ｮ ｾ ･ ｲ ｮ ｡ ｬ labor costs at NASA/Lewis and thereforedo not representultimate costsunder mass production conditions

SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

Not available in ｲ ｾ ｦ ｰ ｲ ･ ｮ ｣ ･ Ｌ details requ?stedfrom ｡ ｾ ｴ ｨ ｯ ｲ of ref.

1 watt modules of silicon solar cells ｷ ･ ｲ ｾ ｵ ｳ ｾ ､ Ｎ These wereprotectedwith .005" FEP Ｈ ｦ ｬ ｯ ｵ ｲ ｩ ｮ ｡ ｴ ｾ ､ ethylenepropylene) films.Modules were mounted at 45 deq.

Under a variety of conditions, PEP showed no degradationunder｢ ｾ ｩ ｧ ｨ ｴ sunlight (7 years in Florida) and little or no effect ofdirt accumulation, in two years on top of a building at NASA/Lewis(in a dirty industrial atmosphereenvironment). The FEP (Teflon) isquite slippery and this, ｣ ｯ ｭ ｢ ｩ ｮ ･ ｾ with 45 deq. tilt of the arrays,results, cccordiJ:g to the ore-of., j n vi. rt 11011v no observabledegra-dation in traammitted light.

REFERENCE A. Forestipri, Ｂ ｾ ｨ ｯ ｴ ｣ ｶ ｯ ｬ ｴ ｡ ｩ ｣ Terrestrial Applications",Procedings0f the PHOTOVOlTAIC CONVERSION OF SOLAR ENERGYFOR TERRESTRIAL APPLICATIONS Worksho. October, 1973.National Science Foundation/RANN Report NSF-RA-N-74-013

_. I

SYSTEr1DESCRIPTION

___ Ｇｾ｟ _9 Z "__" __ ,PRELIMINARY SURVEY OF TERRESTRIAL ａｐｐｌｉｃａＷｉｏｾ［ｓ OF PHOTOVOLTAIC ISOLAR ENERGY CONVERSION ｓｙｓｔｒｾｓＮ (By J. ｗ ･ ｩ ｮ ｾ ｱ ｲ ｴ for the NationalAcademy of SciencesAd Hoc Committee on Energy Technologies for ｌ ｄ ｃ ｾ ｊ

ArrLICATIOH, ｖ ｉ ｾ ｆ (()() "'1Hz ｡ｮｾ ［ｾｾ ""1'7.) renp.1ter stations, ｲ ･ ｭ ｯ ｴ ･ ｬ ｾSTATUS nrernted in Janan. Five ｳ ｹ ｳ ｴ ｣ ｾ ｳ rpported ｯ ｾ ｮ ｲ ｡ ｾ ｩ ｯ ｮ ｡ ｬ

i '" 19 F. 1 (p ｾ f. 1; e I 0'",)

Array Type:Si lin a"rlicOther COT7JponentsSize: ｲ ･ ｳ ｩ ｾ "

ｾＭＭＭＭＭＭＭＮＮＮｉ

)2 - 130Vo1ts DC(peak)*

Current II

, - 10 Power (watts)

Supplier: ｾ ｬ ｪ Ｇ Ｇ Ｇ Ｇ ｲ Ｈ Ｉ ｮ Elp.C'trir C0.Solar nanel,NiCd

Cost Ｈ Ｄ Ｏ ｋ ｾ Ｇ ｔ ･ ｮ ･ ｡ ｫ Ｉ $ 110/'·;attf,,) f"'lr ｲ ｏ ｊ Ｂ ［ ｝ Ｂ ｾ ･ ｴ ｦ Ｇ ｳ ｹ ｳ ｴ ･ ｔ ｾ Ｎ ｢ ｩ ｬ ｴ ｴ ･ ｲ ｴ ｣ ｳ Ｌ ･ ｴ ｣ Ｎ

LOCATION, DA'l.'E ｾｴＭ ｓｉＱｩＮｮｮｾＱｴＱＬ l'Hj1/'·''':. ｾ Ｇ Ｚ ｩ Ｋ Ｚ Ｌ ｵ ｩ Ｚ ｩ Ｑ Ｙ ｦ Ｐ Ｏ ｍ ｴ ｾ t1oki, ]9601OF DEPLOYHENT f\'iJtSUi'l'11C', (.;n .... ｾ :'l!:r. ｾ ｬ ｩ Ｇ ｬ ｜ Ｍ ｡ ｴ Ａ Ｌ ［ Ｚ ｖ ｔ ［ Ｉ ｙ Ｌ I 1 C)({)

PARTICIPATINGORGANIZATION:)

ｾｩｲｮｯｮ ｅ｝ｰｲｾｲｩ｣ rc ..T' i ＨＢｾ t" ＬＡＢＢＬＧＺＬｾ n "Y'le yo r-,c, -:, 0 '

r .... n. /"'!11? B"'0a r 'cv::::tinn e"'l.,rr 'l'r") .... "t·" l'<'] PC. ｐ ｲ Ｎ ｾ ﾷ Ａ Ｈ ｾ ｲ Ｎ Co ..... ｾ __+-__M_._. .:..._ ._= .__.,'_. .__-.lI..,.,/,

COW1ENTS

SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

Sy::;tcm infor:'latio:' 0i",rr->n in the nrecl"".!inn ary"Tlic<1tion SUl(m:,r" sheetalso ｡ ｾ ｰ ｬ ｩ ｾ ｾ ｾ ｾ ｲ ｮ Ｎ

98_... 1.

PRSLHlINARY SURVEY OF ＧｬＧｆＮｒｒｾｓｔｐＮｉＮｉ｜ｌ APPLICl\TIONS OF PHO'rOVOLTAIC ISOLAR ENERGY CONVERSION ｓｙｓｾｅｍｓＮ (Ry J. ｗ ･ ｩ ｮ ｾ ｡ ｲ ｴ for the NationalAcademy of SciencesAd Hoc Committee on EnePfJ Technologiesfor ｌ ｄ ｃ Ｇ ｾ

AP:2LICATION, S01ar. r.C'·'0.reri " r1 tH''3tiona1 t0 l '?vie,ion in ｎ ｩ Ｙ ｾ ｲ ｩ ｡ Ｎ

STATUS ｆＧｩｴＢｾｴ :-"S"I""1S rfl0.rat:ion",l Ｇ ｾ Ｂ Ｑ Ｎ Ｑ Ｙ ｆ ］ ｾ (prntotYflP),r r:> r:m 1a r '1 ｾ e j:-: 1 ｾｰ 2 (s be ｾ r:hn()1s )

SYSTEMDESCRIPTION

Array Type: Si 1.; conSize :I?J''( 4 7 nnou1es.t--------.....A

12 or Ｒ ｾ ｯ ｬ ｴ ｳ DC(peak)*

Current l!

Power (watts)

Supp1ier: PTr

Other Components

27 ｮ ｾ ｰ ･ ｲ ･ Ｍ ｨ ｯ ｵ ｲ battery(16 ｾ ｡ ｾ ｴ ･ ｲ ｹ ･ Ｑ ･ ｾ ･ ｮ ｴ ｳ Ｌ CIPELt:Tr, "1. 201)

? ｴｹＧｾＨＧ ('T 17 (L:-1n) transistorｴ ｬ ｾ ｬ ｣ Ｇ Ｚ ｩ ｳ ｩ ｃ ｬ ｮ sets

'T'V .::l!,t0nna anr. c3b 1echnrr;e J i;r,i.tcr

LOCATION, DA'I'E Vi'-'<:is r . 0 ,/':; ｓ ｣ ｨ ｃ ﾷ ｾ ｬ

OF DEPLOYMENT

PARTICIPATINGORGANIZATIONS

"':tticn"'ll ｾ ＾ ｬ ｜ ｬ ｣ ｬ ｴ ｩ Ｈ Ｇ ｮ Ｈ ｬ ｬ 'T'cl"'''ic;1n'1 S"stt?P1 of Y'Ji<)eriCl,Ｐ ｾ Ｔ Ｐ ｩ Ｈ Ｇ Ｐ r,f Sol<:\r EC"ler'"1v (1'1i ＺｬｾＰ＿ＩＬ plfe C'7'rZl.:1ce) I

1-----0+-----------.,.

COMHENTS

......------_..&.._-----------------------_._--(SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

ｔｾＺＨＧＺ cost of the ｣ Ｂ ｩ Ｌ ｾ ｽ ｪ ｶ ｾ ｲ Ｚ ｶ ｊ .:md ｩ Ｚ ［ ｳ ｴ ｩ Ｇ ｬ ｬ ｝ ﾷ Ｇ Ｈ ｾ n lv)1:ovolt.J.ic array in ｾ ｬ ｩ Ｇ ｔ Ｎ ［ ｲ

ｾ Ｌ Ｎ Ｇ Ｌ Ｌ Ｚ Ｎ 16,500 Fr. Ｇ Ｑ Ｇ ｨ ｩ ｾ is ｲ ｃ ｬ Ｎ Ｑ ｣ ［ Ｇ ｾ ｬ Ｇ Ｚ ｾ 100 npr ｰ ･ Ｚ ｬ ｾ Ｚ ,··,:,tt. On the bosis0f ｾ ten year life ｾ Ｐ ｲ Ｋ ｾ Ｐ ｮ ｾ ｮ ｾ ｬ (V0ry ｾ ｃ ｬ ｮ ｳ ｾ Ｍ ｶ ｾ ｴ ｪ ｶ ｾ Ｉ Ｌ ｴ ｾ ｇ cost of;m 'lour Ｈ ｾ ｦ tr> lGvi s i 0:1 is.1)8 T"r co!"",,, -:-ed '...'i tl; 1 .4 for ;) hilttcryｳ ｾ Ｇ Ｌ ｴ ･ Ｚ ｴ Ｇ Ｎ 'J'hr.) C0;.;t d00:"= !"ot: ｲ Ｂ Ｇ ｦ ｬ Ｈ ｾ Ｚ Ｚ Ｚ ｴ Ｚ In'' ar.1orti1inti0n chf:1r<]cs.Th.; ｳ ｶ ｳ ｴ Ｂ Ｇ ｾ ｭ ｩ ｲ Ｎ Ｌ Ｚ Ｌ ｬ ｴ ｬ ｲ Ｔ ｾ ｓ 0. '::Ol;:lr ".'l:.01 CO'1:;t.rur.tcd frClT:1 :.i v rpx modules":0.47, to ;,rov;,(''-' ,]. toto.l 1")C''11.-, ")l"')"!E'r ('f 48 '.ntts;a 27 ampere-hour＾ ｡ ｾ ｢ Ｚ ｲ ｹ ｣ ｯ ｭ ｲ ｮ ｳ Ｂ Ｂ ｾ ｾ ｦ 16 ·'l.,;,nent'"I CIPJ.L 'l'ype 'J1. 203 (??); a ｣ｨ｡ｲｧＨｾ

1i.;,itrr, .1 ｴＭ｣ｬ｣ｶｩＧＭｾＺｩｦＢＩｮｾＭｴｾｮｮＬｬ ur,::' c.:' ｾ Ｎ ｃ Ｇ Ｌ ｾ nr,},:,T' ｣ ［ Ｂ ｾ ｾ ･ and b·roｴ ｲ ｡ ｮ Ｚ Ｍ ｩ Ｇ Ｓ ｴ ｣ ｬ ｬ ｾ ｪ Ｒ Ｈ Ｇ Ｈ ｾ ｄ Ｎ ｾ ﾷ Ｚ Ｎ Ｇ t.0'C'·,.··."i"'n Ｍ ｾ ｾ ﾷ ｃ Ｎ Ｌ 1+.·,,- ('T" I.,. B"n'

REFERENCE

99_-----------------ac..IIC...---- ,PRELIMINARY ｓｕｒｖｅｾｾｆ ｔｅｾｒｒｓｔｒｉａｌ ａｐｐｌｉｃａｔｾｏｎｓ OF ｐｈｏｔｏｖｏｌｔａｾｃ ISOLAR ENERGY ｃｏｎｖｾｒＰｉｏｎ ＰｙｓｾｅｍｓＮ (By J. ｗ ･ ｬ ｮ ｾ ｡ ｲ ｴ for the NatlonalAcademy of SciencesAd Hoc Committee on Enercy Technologies for ｌ ｄ ｃ ｾ ｉ

Ai>PLICATlmJ,STATUS

Solar T"'o"lered ;)UOVS

Ｈ ｾ ｸ ｰ ･ ｲ ｩ ｲ ｮ ･ ｮ ｴ ｳ with ｰ ｲ ｡ ｾ ｯ ｴ ｹ ｰ ･ ｳ Ｉ

SYSTEMDESCRIPTION

Array Type:Size:

Other Components

NlA

Volts DC(peak)*

Current 'tPower (watts)

Supplier:

Cost Ｈ Ｄ Ｏ ｋ ｷ ･ ｄ ･ ｡ ｾ Ｉ $ｾＭＭＭＭﾷＮＮＮＡＮＮＺＺﾣＮＴＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭ

LOCATION, DATEOF DEPLOYHENT

PARTICIPATINGORGANIZATIONS

u.s. ｾ ｯ ｡ ｳ ｴ Guard + ??

...c_O_t_,1r_,rE_'N_T_S ---IL...-._-_- ·= .. ------------JSYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒ＿ｏｒｾａｎｃｅ

REFERENCE ｈ｡ｶｩＩＱｾ ＧｾﾷＮｴｵ､Ｚｊ 'Tor'rest-ria1 !\j:mlic3tions of So18.r CellP,...,l1/ered ＺＧｾＺＬＢｩＩｴＧＲｴＺｬｓＧＺＬ ｲ［ｯｾ 10t0i{ riv. of Textron 1073( ｾＢｃＩ r "U\.:; f.! LC"!i ｾ ｟ ［ f' '::' Se·q rch Cor. t c r )

100PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. Weingart for the National ,Academy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

APPLICATION,STATUS

SYSTEMDESCRIPTION

ｾ ｡ ｲ ｩ ｯ ｵ ｳ experimentalapplicationsof RTC solar cells

(Details on following sheets)

Other Components

Volts DC(peak)·

Current "

Power (watts)

Supplier:la RTC ｒ｡､ｩｯｴ･｣ｨｮｩｱｵ･Ｍｃｯｭｰｬｾ｣Ｌ

75 Paris lleme, ｆ ｲ ｡ ｮ ｾ ･

Cost ($/KweDeak) $

LOCATION, DATEOF DEPLOYMENT

PARTICIPATINGORGANIZATIONS

COMMENTS

SYSTEM DESCRIPTION/PERFORMANCE

130 Avenue Ledru Rollin

"

19601968

1971

1973

197319731973

Powering of an experimentalstation in ChilePowering of a radio-beacon (50 w) for the Service Technique

de la Naviaation Aerienne (St. Girons ｮ ｾ ｡ ｲ Bordeaux)Powering of a radio repeaterstation (12 w) as a permanent

installation for the National Center for the Study ofTelecommunications(France)

Powering of seven warning lights (?) for the airport of ｍ ･ ､ ｩ ｲ Ｎ ｾ

in Saudi ArabiaAn experimental Ｈ ｲ ｾ ･ ｭ ･ ｴ ｴ ･ ｵ ｲ Ｉ Ｌ 25 w, installed in South ａ ｭ ･ ｲ ｩ ｣ ｾ

A maritime navigationalwarning light, 36 w (France?)Solar powered television sets in Niger

The basic RTC module is fabricated from silicon solar cells madefrom circular slices of single crystal silicon. The Module TypeBPX 47 contains 64 silicon solar cells, each 4 em in diameter,mounted in a clear epoxy fOF protection. The net conversionefficiercyunder AMI conditions is ten ｾ ｾ ｲ ｣ ･ ｮ ｴ Ｎ These modules have a net poweroutput under AMI conditions of 8 watts at 12 or 24 volts.

REFERENCEB. Dalibot, "GenerateursSolaires Pour Applicationsｔ ･ ｲ ｲ ･ ｳ ｴ ｲ ｾ ｳ Ｂ Ｌ Ｐ ｲ Ｐ ｣ ･ ､ ｩ ｾ ｧ Ｓ of th0 1973 International SolarEnergy Society meeting Ｈ ｐ ｡ ｲ ｩ ｾ Ｉ Ｌ p. 565

- "·PRELITUNARY SU:NEY OF ｔｾｐｒ［Ｚ［ＭＺｓｔｈｉａｌ ＮｾＮｐｐｌ TCATTO;·J:) OF PHOTOVOLTJ\IC ISOLAR ENERGY CONVERSION ｓｙｓｲｲｆＬｲＬｾｳＮ (Ry J.' l,o]p; ｮ ｲ Ｚ ｾ ｬ ｲ ｴ for the Nat] analAcademy of SciencesAd Hoc Committee on ｆ Ｎ ｮ ･ ｲ ｾ ｹ ｔ ･ ｣ ｨ ｮ ｯ ｬ ｯ ｾ ｩ ･ ｳ for LDCf)

APPLICATION, Pi rot b,rr"otrl 0 1 Ｌｮｾ licot 1nn1 Pr;"'ar:: n<uer >ource ISTATUS fnr a nell t':r" P r'1r.i1 1 carrier ｾ Ｂ ｳ ｴ Ｈ Ｇ ｔ Ｇ Ｑ (telephone).

0nl?ratec' ｮ ｣ ｴ ｯ ｾ Ｉ Ｌ ｾ ｲ Ｌ 1955 until ｾ Ｂ Ｌ Ｑ ｲ ｲ ｨ Ｌ 1956.

22 Volts DC(peak)*

Current "JI) Power (watts)

SYSTENDESCRIPTION

Array Type:Size:

Other Components

ｎ ｩ Ｍ ｃ ｾ ｢ ｒ ｾ ｴ ｣ ｲ ｹ ｡ ｲ ｲ ｾ ｶ Ｌ 22 v,1 r:; :lr;..,-hours

Supplier: ＿ ｾ Ｑ Ｑ ｾ ｡ ｴ ｲ ｲ ｮ ｾ ｾ ｲ ｩ ｮ ｾ

LOCA'l'ION, DATEOF DEPLOYMENT

PARTICIPATINGORGANIZATIONSｴＭＭＭＭＭＭＭＭＭＭＧｩＭＭＭＭＭＭＭＭＭＭＭｾＭＭＭＭ ..ＭＭＭＭＭＭＭＭＭＬｾＭＭＭＡCOMMENTS

.....-------_-...._._-------_._-----------------_.SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

REFEREnCEｃｾＮＮ T) " rl r ,. ,.,;,. .. .' .,.< 1. .ｾ i d: ' ('" ':: ." C n 1 ｾ t r '.' r) 1 t :, ｾ .. c Cp J 1 ｾ ｾ 1"'

;·.,..,....... ｾｬＬＮＬＮＮＮＮＮﾷ［ .. ｾｾＭﾷﾷｩｮ［Ｚ［［｜ｬ ｾﾷＢｊｲｾＨ ...·--.':,;n.'1.-.; 0f ｴ ｪ Ｎ Ｑ ｾ T"T'! t'nn'fp'r'("'lr.( .. ,.""'\ ....1: .. ｾＮ｝1')(] Ｈ Ｂ ｲ Ｚ ｩ ｴ Ｚ Ｂ ｾ "_1ti0ns)

102PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. ｗ ･ ｩ ｮ ｾ ｡ ｲ ｴ for the National JAcademy of SciencesAd Hoc Committee on Enerey Technologies for ｌ ｄ ｃ ｾ

APPLICATION,STATUS

Experimentalphotovoltaic generatorat the Univ. ofChile in cooperationwith RTC. 1961Status unknovm

SYSTEM'DESCRIPTION

Array Type: SiliconSize:

1----------1

3.3 Volts DC(peak)·

26.5 Current"

87.45 Power (watts)

Supplier: RTC

Cost ($/Kwepeak) $ N/A

LOCATION DATE Chilean ｾ ･ ｳ ･ ｲ ｴ , 1961,OF DEPLOYMENT

Other Components

PARTICIPATINGORGANIZATIONS

COMMENTS

University of Chile, RTC'

SYSTEM DESCRIPTION/PERFORMANCE

The system included a photovoltaic array made up of 144 modules,each containing 36 solar cells 1.9 em in diameter.

REFERENCEB. Dalibot, "GenerateursSolaires Pour Applications Terr-estres", ｐ ｲ ｯ ｣ ･ ､ ｩ ｮ ｧ ｾ of the InternationalSolar EnergyConference,Paris, 1973 p. 565

II

i

103PRELIMINARY SURVEY OF TEPRESTRIAL APPLICATIONS OF PIIOTOVOLTAICSOLAR ENERGY CONVERSION ｓｙｓｔｅｾｓＮ (By J. Weineart for the National Ｎ ｾ

Academy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

f

APPLICATION,STATUS

Lighthou,;c - Power fnr Remote ｾ Ｇ ｬ ｡ ｲ ｮ ｩ ｮ ｧ T,j gr.t::;Eight systemsonerational in Japanby 1961. Presentstatus no known by author.

SYSTEMDESCRIPTION

Array Type: Si, sealed Other ComponentsSize: in ｡ ｣ ｲ ｾ ﾷ ｬ ｩ ｣ resin

ｾ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ Ｍ (See Fig. ) Ni-Cd hatteries12-&86 Volts DC(peak)* Protective diodes

Current "

12-30 Power (watts)

Supplier:NipponElectric Co.diodes, controls,

Cost ($/Kweneak

) $130/watt ｾ ｮ ･ ｾ ｫ Ｉ ｩ ｮ ｣ ｬ ｾ ､ ｩ ｮ ｧ hattery, containers,

LOCATION, DATE Ei(Tht systems ､ ･ ｲ ｬ Ｂ Ｇ ｹ ｾ ､ bet.,,'eenNov. 1!}58 and Dec.,OF DEPLOYMENT 1960 in Japan (Se0 Table )

PARTICIPATINGORGANIZATIONS

COMMENTS

Japan Maritime Safety R9ard, ｎ ｩ ｰ ｾ ｯ ｮ Electric Co,Ltd.(.Tapan)

Battery ｭ Ｓ ｩ ｾ ｴ ｡ ｮ ･ ｮ ｣ ･ required ｴ ｷ ｩ ｣ ｾ per year, nooperationalproblems seen between aeploymentandAugust 196] reoort (:;ef. he10'-")

SYSTEM DESCRIPTION/PERFORMANCE

In 1961, the experienceof ｴ ｾ ･ Japanese.in the use of small, remotephotovoltaic systems for VHF rerearterstations arlrl for lighthouse(unattended)operationwas reported. At that time, at total of eightremote lighthouse installationshad been Made and were operating.The systems included a twelve volt siliron solar cell array sealedin an acrylic resin and mounted in a rugged frame. (Fig. ). Thepower (peak, AMI is assumedin absenceof specific ｳ ｾ ｡ ｴ ･ ｭ ･ ｮ ｴ in ref.ranged from 10'watts to 29.5 watts. The number of individual cells,produced from cjrcu]ar slices of ｾ ｩ ｮ ｧ ｾ ･ crystal ｳ ｩ ｬ ｩ ｾ Ｐ ｮ Ｌ ranged from648 to 1404, with indj.vidual snbmodulescontaining nine cells each.Actual converson ･ ｦ ｦ ｩ ｣ ｩ ･ ｾ ｣ ｹ for the ､ ｾ ｰ ｬ ｯ ｹ ･ ､ modules was not given.However, the referenceindicates that" Lately, •• , ｴｨｾ efficiencyhas been raised from 8 percent to 12 percenton the average. Themaximum efficiency of 18 percentwas obtained in our company".Orientation of the panelswas due South, oriented at an angle equalto the latitude. The cost of power lines in remote mountainousre-gions of Japan in the early 60's is reported to be between five andseven thousanddollars per kilometer. For solar powered systemsof50 watts or less such systems, at 130 dollars/watt installed thesesystemsare less expensivethan a one kilometer power line. (Fig. )

REFERENCE M Kobayashi, "Utiliyation of Silicon Solar ｂ ｡ ｴ ｴ ･ ｲ ｾ ･ ｳ Ｂ ＬProcedingsof the ConferenceNEW SOURCES OF ENERGY, p.

5-11, Volume 4(Solar Energy:I). August, 1961, United Nations

ＭＭＭＭＭｾ ＭＭＭＭＭＭＭＭＭＭｗａｾﾷ ｾ -. ＭＭＭＭＭＭＭＭＭＭｾﾷＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭｲPRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEf,1S. (By .J. Weingart for the NationalAcademy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

I\nnr Tnl\rnT""t.ttl. J. .1J_L\Jt1.J...LV!,. ,

STATUSISolar Cell Powering of Remote Atmospheric Monitoring

ObservationStations (RAMOS) for use by NOAA. Onesystem operationalOttobr>r, 73. Others to follow.

cnvers

SYSTEfl[DESCRIP'rION

Array Type: Silicon Other ComponentsSize: pith FEP ｩ ｮ ｴ ｦ ｾ ｲ ｡ ｬI--------...l

Volts DC(peak)*

Current "

60 Power (watts)

ｓ ｵ ｰ ｰ ｬ ｩ ･ ｲ Ｚ ｎ ｾ ｓ ａ +ahricat0.d

LOCATION, DA'I'E Sterling,VirC]inia (1973),Mammoth Moun'tain, Califor.OF DEPLOn,mN'l' 1973, someYThere in Alaska

PARTICIPATINGｏ ｒ ｇ ａ ｎ ｉ ｚ ａ ｔ ｉ ｏ ｎ ｾ ｪ

\JASA, NOAA

COMMENTS

SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

A NASA/Lewis project reported on in 1973 is the design,fabricationand construction Ｈ ｾ ｦ a. number of solar powered remote stations foratmosphericroonitorinq.Detailshave been requestedfrom the authorof the ref. below.

Macrr'nth IV'oll"'.tai n racili t.y: Solar array is made up of modules, eachcontaining 48 (6 by 8) circular solar cells. Total array contains20 modules (3 watts peak AMI each). Cells are encapsulatedinFEP dheets.

A. Rosenblatt, "Energy Crisis Spurs Developmentof Photovoltaic ｐ ｯ ｾ ･ ｲ Sources", Electronics (G.B.) April 4,1974

REFERENCE r,. Forestieri, "Photovoltaic Terrestrial Applications",Procedingsof the PJ-JOTOVOLTAIC CONVERSION OF SOLAR ENERGYFOR TERRESTRIAL APPLICATIONS Workshop, October, 1973.National Science F0undation/RANN Report NSF-RA-N-74-013

105PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. ｗ ･ ｩ ｮ ｾ ｡ ｲ ｴ for the National ｾ

Academy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

APPLICATION,STATUS

SYSTEtJ1DESCRIP'I'ION

｜ｾＱｆ RepeaterstationsLisrhthousesLightbuoysｾ Ｇ Ｑ ｩ ｲ ･ ｬ ･ ｳ ｲ Ｚ telephones

Array Type:SiliconSize:

(.JAPAN)

Other Components

Volts DC(peak)·

Current II

Power (watts)

Supplier:

Cost ($/Kwepeak) $

LOCATION, DATEOF DEPLOYHENT

PARTICIPATINGORGANIZATIONS

COMMENTS

SYSTEM DESCRIPTION/PERFORMANCE

The Inrgest solar power ｳ ｹ ｳ ｴ ･ ｾ ｩ ｾ Japan·was developed for theMaritime Safety Board. It ｰ ｲ ｯ ｶ ｩ ､ ｣ ｾ a peak power of 1156 wattsand was installed in a lighthouse in 1966. Japanhas installeda total of 4G13 Vl:C, tts of so ｾ ar Ｈ Ｇ ｮ ｣ ｲ ｬ ｊ ｾ Ｇ nC\oJ0.r Sy"f:CflS (; uring theｲ ･ ｲ ｩ ｯ ｾ from !95R to 1966. ｔ ｾ ･ major use ｾ ｦ ｴ ｨ ｩ ｾ equipment is forVHF ｲ･ｾ･｡ｴ･ｾ ｳｴｾｾｩｯｾｳＮ

REFERENCE F'. Costoque n:-.d E. Vi vi .:If', "Snlar Energy RechZlrgeablerower ｓ ｹ ｳ ｴ ･ ｾ ｬ ｬ Ｌ internal document of the Caltech JetPropulsion Laboratory, June 15, 1969. JPL documentNo. £.50-81

ＱＰｾ

PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. Weingart for the NationalAcademy of SciencesAd Hoc Committee on Energy Technologiesfor ｌ ｄ ｃ ｾ

APPLICATION,STATUS

Remote data ｾ ｴ ｡ ｴ ｩ ｯ ｮ in Fairbanks, Alaska,operational in the late 60's, presentstatusunknown

SYSTEM A:ray Type:Si...D_E_S_C_R_I_P_T_IO_N__• S1ze: . 7 f t 2

Volts DC(peak)*---Current II

7 Power (watts)

Supplier: Hoffman/Motorola

Cost ($/Kwenea ) $

LOCATION, DATE Fairbanks, AlaskaOF DEPLOYMENT

PARTICIPATING ??ORGANIZATIONS

COMMENTS

SYSTEM DESCRIPTION/PERFORMANCE

Details not provided

Other Components

13.6 V battery18 watt transmitter

1960's

REFERENCE E. Costogu(> & H. Vivian, "Solar Energy RechargeablePower System", internal document of the Caltech JetPropulsion Laboratory, .Tune 15, 1969. JPL DocumentNo. 65()-81

, 107PRELIMINARY SURVEY OF TERRESTRIAL APPLICATIONS OF PHOTOVOLTAICSOLAR ENERGY CONVERSION SYSTEMS. (By J. Weingart for the ｎ ｡ ｴ ｩ ｯ ｮ ｾ ｬ ｾ

Academy of SciencesAd Hoc Committee on Energy Technologies for ｌ ｄ ｃ ｾ

APPLICATION,STATUS

Pemote communicationse0uipment, Californiaｄ ･ ｰ ｡ ｲ ｴ ｭ ｾ ｮ ｴ of Parks

ｓ ｙ ｓ ｔ ｅ ｲ ｾ

DESCRIPTIONArray Type: SiliconSize: 4 'Ilatts

Other Components

Volts DC(peak)*---Current It

4 Power (watts)

Supplier: 88f!&aS88S Motorola

Cost ($/Kweneak) $

LOCATION, DATE ? reployed in 1968OF DEPLOYMENT

,

PARTICIPATINGORGANIZATIONS

COMMENTS

State of California,ｾ ｯ ｴ ｯ ｲ ｯ ｬ ｡ Electronics (Scottsoale,Ariyone)

Insufficient information in reference

SYSTEM DESCRIPTION/PERFORMANCE

Motorola r.ommunicationsenuinment, operatedfrom aNi-Cdbattery charged by , 4 watt (peak) ｳ ｩ ｬ ｩ ｣ ｯ ｾ solar ｡ ｲ ｾ ｡ ｹ Ｎ

Use of Eveready air cells, ､ ｩ ｳ ｮ ｯ ｳ ｾ ｾ ｬ ･ after one year operation,requires annual transpnrtationpll1S cost fJf batteries.

Batteri.esｔ ｲ ｡ ｮ ｳ ｾ ｯ ｲ ｴ

$ 15'1.$ 100.

TransporationvJoulc1 be by ｨ ｯ ｲ ＼ ［ ｾ ｢ ｮ ｣ ｫ or helicorter. Clearlythe systemsavailable in 1975 would easily be cost effective,since a ｾｯｭｰｬ･ｴＰ system could be obtained for less than fortydollars per peak watt, ｪ ｮ ｣ ｬ ｵ ｣ ｩ ｮ ｾ batterip.s and charge limiter.

REFERENCE E. Costagueand H. Vi vi e1.1", "S01<1r EY"iergy RcchargeabIePower Svstem", internal document, C';1ltech Jet PropulsionLaboratory, June 15, 1969. JPL document No. 650-81

108.------.--.--. 1PRELHlINA.RY SURVEY OF TERPF.STRI/IL APPLICATIONS OF- PHOTOVOLTI\IC ISOLI\R ENERGY CONVERSION ｓｙｓｔｅｾｓＮ (By J. ｗ ･ ｩ ｮ ｾ ｡ ｲ ｴ for the National I

Academy of" SciencesAd Hoc Committee on Enerey Technoloeics for ｌ ｬ ｊ ｃ ｾ

1"\rPLICATION, 1Aids to Navigation Equipment for off-shore oil ISTATUS platforms (currently installed on one platform)

Current "

Volts DC(peak)*

120 Power (watts)

Supplier: Solar Power Corp.

SYSrrEMDESCRIP'rION

Array Type:Size: 122 cm x 152 cm

I

Other ComponentsOne 2-mile fog signalFour 5-mile lamps28 100 amp-hour deep dis

charge batteriesone electronic voltage

monitorHousing & supports

Cost ($/Kweneak) $(approx. $ 20,000)

ｌ ｏ ｃ ｉ ｜ ｔ ｉ ｏ ｾ ｊ Ｌ DAl'EOF DEPLOnmNT

Approx. 1973 (Texas Gulf Coast?)

A total of 80 modules (Solar Powerpeak/module

ｃ ｏ ｗ ｾ ｅ ｎ ｔ ｓ

PARTICIPATINGORGANIZ ArrTONS

Complete system was fabricated andSignal Corporation, Houston, Texast-------,- ...J?Qwe.r.....G.Qrp..｟ＺｾＬｵＮＮｬＮ･Ｎｳ __.

sold by Tidelandusinc Solar I

Corp.), Ｍ ｾ Ｍ Ｍ ｷ ｡ ｴ ｴ ｬ......ＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭＭｾ 1

SYSTEM ｄｅｓｃｒｉｐｔｉｏｎＯｐｅｒｆｏｒｾａｎｃｅ

REFERl:\lJCE B. Kelly et a1, "In'JestiGatlonof Photovoltaic Applica-ｴ ｩ ｯ ｾ ［ ［ Ｌ Ｑ Ｇ ﾷ Ｌ prt:sented at the Intcrnational Congress,The Sun in theService of J.1ankll1d, Par-i" , 1973.

The lighting system on the referencedoil platform consistsof one2-mile fog ｳ ｩ ｧ ｮ ｾ ｬ and four 5-mile lamps. Enersy consumption is about25 am-hour/day x 12 volts = 300 whe/day. Previously this liGhtingsystem was powered by 40 1.2 volt, 3300 amp-hr primary batteries.The total weight was 2,000 Ibs and these were replaced annually. Thesolar generatorsystem incorporates80 photovoltaic modules (1.5 wattspeak under AMi illumination, 25 deg.C) into an array with overalldimensions 4 x 5 feet (1.22 x 1.52 m). The reference implies a retailcost of roughly $ 20/peak watt and indicates tJ)at at suc;h prices fora terrestrial array (sealed, ready to install), such arrays begin tocompete with primary and secondarybatteriesin markets traditionnallylserved by this hardware. The ref. claims that "solar cell/secondary Ibattery systemselearly compete on an economic basis with heavy dutyprimary batteries" (presumably on a life-cycle cost basis, althoughthe slJecific numerical dotails are not discussed). I

lIIIIIII

No. Letter

B

C

D

F

G

H

I

K

109

Reft'?rence

Science, Te',:ht'lology and Development, Report ofthe United Nations Conferenceon the ApplicationConferenceon the Application of Science andTechnology f01' the Benefit of Less DevelopedAreas. Volume II. Natural Resources,ｕ ｮ ｩ ｾ ･ ､ Nations, New York, 1963

C. ,3. Currin ar:d W. A. Smith, "Economic s ofSilicon For Future Large Solar Cell Arrays"

R.J. Mytton, "The PresentPotential of CdSSclar Cells as a Future Contendor for Photo-voltaic Space and TerrestriOil Power Applications"So],ar Energy" Vol.16, pp. 33 - 44, August 1974

E.l'L Costagueand H.C. Vivian, "Solar Energyｒ ･ ｜ ｾ ｨ ｡ ｲ ｧ ･ ｡ ｢ ｨ ［ POvJer Systemll JPL Document 650-81,June 15, 1969. Jet Propulsion Laboratory,Pasadena,California, 91103

Product Data Sheet "Solarex Solar EnergizeI'll,Bu]letin No. SE-3, Solarex Corporation, 1335PiC':::ard Ave:lue, Rockville, Maryland 20850

e.G. Currin e:, aI, "Feasibility of Low CostSilicon Se:lar CellS", Proceedingsof the NinthIEEE PhotovoLtaicsSpecialistsConference,May 4, 1972

A.S. Spako'!Jski, "A:: Estimate of the Cost ofLarge-Scale?ower GenerationUsing Solar Cells",Procepdings01' the Ninth IEEE Photovoltaicsｓ ｰ ･ Ｈ ｾ ｩ ｡ ｬ ｩ ｳ ｴ ｳ Conference,May l4, 1972

A.1. Mlavsky, "The Silicon Ribbon Solar Cell -A Way ｾｯ Harness SoLar Energy", Tyco Laboratories,Waltham, Massachusetts,02154, June 1974

B. KelJey at aI, "Investigation of PhotovoltaicApplicat;iuns", International Congress,The Sunin the Service of Mankind, July 5, 1973, Paris

R.J. Stirn, "Feasibility of Economical SiliconSolar Cr:ll Production", JPL Interoffice MemoNo. Ｓ ｾ ｪ Ｍ Ｗ Ｍ Ｇ Ｏ Ｑ Ｍ Ｔ Ｓ ｾ Ｌ July 27, 1971

R.J. Stirn, "Gallium Arsenide Solar Cells"', JPLInteroffice Memo No. ＳＴＲＭＷＰＭａＭＵＱｾＬ Jet PropulsionLaboratory, Pasadena,Calif., December 16, 1970

No. Letter

L

o

P

Q

R

rr

u

v

110

Reference

i'l. nClkawama, "Ceramic CdS Solar Cell", JapaneseJournal of ａ ｰ ｰ ｾ ｩ ･ ､ Physics, Vol. 8, No.4,pp. 450 - 462, ａ ｰ ｊ Ｚ Ｇ ｩ Ｚ Ｚ Ｍ ｾ 1969 (English)

ij, ｾ ｊ ｡ ｸ ｡ ｹ ｡ ｭ ｡ Ｌ fe'_ al., "Ceramic CdS SoJaI' Cell- SmJCERAM''', ?']a t iOf' ｾ ｴ Ｑ 'rechnical Report,Vol. 15, No. ｾ Ｉ Ｌ Ap['il 1969 (Japanese)

:vI. Wolf, "ft. Nel'; Loc'k at Silicbn Solar Cell?erfnrmance",ElJ2rgy ConversionVol. 11,p. bj-'13, 1911

A. I. Mlavsky, Spmlnar at International Institutefor Applied System Analysis, Laxenburg, Austria.December 1974

Comparison of LO\'1 Puwer Electri cal GeneratingSystems for Remote Application, Preparedforthe National Bureao of Standardsby Thermoｅ ｬ ･ Ｈ ｾ ｴ ｲ ｯ ｮ Corporation, 85 First Avenue, WalthamMassachusetts,Ｐ Ｒ Ｑ ｾ ［ Ｑ Ｌ Report No. TE5317-52-73,1973

J. Davis et al., Proceedingsof the Symposiumon the Material Science ASDp.cts of Thin Filmfor Solar Energy ｃ ｯ ｮ ｶ ･ ｲ ｳ ｩ ｯ ｾ Ｌ May 1974 (NationalScience Foundaticn/RANN, WaShington, D.C.)

A.1. Rosenblatt, "Energy Crisis Spurs Developmentof ｐ ｨ ｯ ｴ ｯ ｶ ｯ Ｑ ｴ ｾ ｩ ｩ ｣ Power Sources", Electronics(G.B.),·April b, 1974, p. 991'1'

Solar ｆ ｮ ･ ｲ ｾ ｹ Ｌ Task Force Report preparedbythe InteragencyTask Force on Solar Energy,under the Dir'ection of thf' National ScienceFoundation, Nov. 1974. USGPO Stock No. 4118-00012

J. Weingart, "Solar Energyll, McGravl-HillEncyclopediaof Environmental Science andTechnoJogy,p. 569, 1974

P. Ehrlich, A. Ehrlich and J.P. Holdren,Human Ecology, W.H., Freeman Company,San Francisco, 1973

An Overview of Alternative Energy Sources forｾ ｳ Ｌ Rr::port to the U. S. Agency for Interna-tional Development,Technical AssistanceBureauOffice of Science and Technology, Preparedbyａ ｲ ｾ ｨ ｵ ｲ D. Little) Inc., Report No. C-77105,AUbust L 197/-1

No. Letter

Ai

Bl

C1

D1

El

111

Reference

Re-bert ,Joseohs, "The Mariner 9 Power SubsystemDesi,R:n and FlifSht Performance", Technicalｾ ･ ｭ ｯ ｲ ｈ ｮ ､ ｵ ｭ ｾ Ｓ Ｍ ｆ Ｑ ｾ Ｌ Jet Propulsion Laboratory,Calif. Institute of Technology, Pasadena,California, May 15, 1973

E. Sequeiraand R. Patterson, "Solar ArrayStudy for Solar Electric Prooulsion Spacecraftfor the ｅ ｮ ｾ ｫ ･ Rendpz-vousMission", TechnicalMemorandum 33-668, Jet Propulsion Labor'atory,Calif. Institute of ｔ ･ ｣ ｨ ｮ ｯ ｬ ｯ ｾ ｹ Ｌ Pasadena,California 91103, February 1, Ｑ ｾ Ｗ Ｔ

R. Pattersonand R. Yasui, "Parametric PerformanceCharacteristicsand Treatment of TemperatureCoefficients of Silicon Solar Cells for SnaceApnlication", Technical Reoort 32-1582, jetPropulsion Laboratory, Calif. Institute ofTechrJoloa;y, Pa:sadena,California 91103, May 15,1973

A.F. Forestieri and A.F. Ratajczak, "TerrestrialApolications of FEP-EncapsulatedSolar Cell Modules"NASA Technical Memorandum TM X-71608, NASA/LewisResearchCenter, Cleveland, Ohio, Seoternber,1974.

112

Referenceson Concentration

1 C. Pfeiffer

2

3

4 W.A. ｂ ･ ｣ ｾ ｭ ｡ ｮ Ｌ P. Schaffer, W.R. Hartman, Jr. and G.O.G. ｌ ｾ ｦ Ｌ

"Design Considerationsfor a 50-watt Photovoltaic Power SystemUsing ConcentratedSolar Energy", Solar Energy 10, 3 (1966)

5 C.E. Backus, "ConcentrationOnt0 Solar Cells", "PhotovoltaicConversionof Solar Energy for Terrestrial Applications", Vol II,Workshop Proceedings,National ScienceFoundation/RANN. October, 1973.

6 P. Schaffer, "High Power Density Solar PhotovoltaicConversion",18th Annual Proceedings,Power SourcesConference,May 1964(University of Wisconsin EngineeringExperiment Station ReprintNo. 702).

7 G.S. Daletskii, A.K. Zaitseva and L.G. Korneeva "Study of SiliconPhotovoltaicConvertersAt High Light Flux Concentrations",Geliotekhnika, Vol. 3, No.2 pp. 3-9, 1967.

8 P. Berman, "Design of Solar Cells for TerrestrialUse", SolarEnergy ｾ Ｇ 3, 4, 1967

9 "More Efficient Solar Cells", Engineering (GB), p. 25, January, 1974.

10 C. Pfeiffer et al, "Performanceof Silicon Solar Cells at High Levelsof Solar Radiation", J. Engineering for Power, Jan. 1962, p. 33.

11 P.A. Berman and E.L. Ralph, "Improved Solar Cells for Use inConcentratedSunlight", Proc. 18th Annual Power SourcesConference,May, 1964.

12 A.Zarem and D. Erway, "Introduction to the Utilization of SolarEnergy", McGraw-Hill Book Co., Inc. 1963, p. 376 ff

I

I,

I

113

Comments on the Thermo Electron Co. Report*

The assumptionsbehind the report strike me as somewhatstrange. If

a village or local community has accessto any useful amounts of electrical

energy at all, then an additional 100 watts for a few hours each day is

clearly well within the local capabilities. Probably a few is of local use.

If there is no electricity available, and the purposeof the study is the

determinationof the best method to provide enough energy for an hour or

two day power for local TV set, it is clear that a few reasonablystrong

people riding an inexpensivebicycle generatorcould charge a battery

sufficiently for such a requirement. Having ridden such a machine myself

at the Lawrence Hall of Scienceat the University of California at Berkeley,

I can testify to the fact that generating100 watts for an hour is possible

but takes considerablestrength. Perhapsa dozen or more member of the

community could take turns at various times of the day to operatethe

generator. If the generatoreventually were no longer used, it would at

least indicate the value which local people placed on having television

links with the rest of the world.

I would maintain that the needsof the LDC's are not TV communications

with the outside world, although ｴ ｾ ｩ ｳ may be heipful PROVIDING THE

NECESSARY ECONOMIC AND PHYSICAL AND SOCIOCULTURAL RESOURCES FOR CHANGE

ARE ALREADY AVAILABLE.

The report is, in my opinion, completely divorced from the realities

of needs in many, if not all, of those LDC's which do not have any major

sourceof wealth. It appearstechnically competantbut not nearly as

useful as it could have been, had the technical study been tied to an

awarenessof real needs. In fact, my own somewhatcynical view of the

problems of developmentprompts me to remark that the last study that was

done to examine remote communicationsfor LDC regions was a study of silent,

reliable systemsto provide military communicationsand village alarm

systems in SoutheastAsia. As it turned out, that was not what the people

neededeither.

*

114

The report is technically deficient in the sensethat is examines

only the cost of owning and operatingvery small generatingsystems (IOOwe).

We need to have costs of owning and operatingvarious systemsas a function

of the size of the output, both for electrical energy and for shaft horsepower

which could be used for irrigation, ｳ ｭ ｡ ｾ ｬ local industry, etc.

Finally, although this is no ｦ ｡ ｵ ｾ ｾ of the authors, the cost of fossil

fuels has gone up since they wrote it. In addition,' I doubt if they (and

I include myself among the-ignorant) have any real idea of the costs of

delivering fuels to remote locations in LDC's (most of the LDC's, by our

standardsof remoteness). The actual costs, when all of the middlemen are

paid in addition to the initial high costs, may be between one and five

dollars per gallon ($ 40 to $ 200 per barrel). Why should we expect

kerosine to be cheaper in the middle of South-centralAsia or Africa than

it is in Vienna (about $ I per gallon)?

The report does emphasizesomething very important, however. The

internal combustion engine, coupled wi-th the very high specific energy

density of kerosine and gasoline, is a marvelousdevice at its best. It

is highly reliable, easily maintainedand repaired, cheap to buy (a few

dollars per kilowatt in sizes of ten horsepowerand up) and quite portable.

However, the authors are too pessimisticabout the eventual cost of

solar arrays. One of the authors (Arvin Smith) was for many years the

central figure at NASA in spacepower systemsdevelopment; his many years

of experiencewith very high cost arrays, coupled with a lack of real

direction in the u.s. in cost reduction for photovoltaic arrays at the

time the report was prepared,have probably resulted in the high cost

estimates. Assuming that arrays can be delivered to LDC's for $ 5 per

peak watt, and the amortization for the array can be over ten years

rather than five, the annual costs of owning and operating a PV system

would be within ten percentor so of the costs for an ICE systemusing

kerosineat a dollar per gallon (delivered).

The difference between a fuel-dependentsystem and a fuel-independent

system cannot be measuredsimply in differences in amortized costs and In

first costs. There may be a significant value to people using fuel-

115

independentsystems in not having to rely on fuels, in not being at the

mercy of fluctuations in the cost of the refined product, in not being at

the mercy of the delivery system, and so forth. However, this is balanced

to some extent by the limited investmentcapital available in the LDC's.

This also leads to the possibility of dual or hybrid systems, including

both photovoltaic and kerosine/gasolin, powered convertors. After all,

if a solar conversion system can be paid for, the additional samll increment

for an engine/generator/regulatorsystem can be assumedpossible. The

engine, coupled with a small amount of standby fuel, could provide necessary

backup for urgent purposesin the event of insufficient sun for long periods

of time. The marqinal return, in terms of a senseof security or reliability

in the delivery of electricity to a community, might be very high.

From a pragmatic short range perspective,which is the only one most people

are interested in, it is better to have a low initial cost and higher

operating costs than the reversegiven equivalent life cycle costs. It

clearly is a question of relative values in small human ecosystemswhether

or not solar or fuel-dependentsystemsor some combination of the two are

to be preferred. With appropriatelydesignedprogramsof action, the

questionscan be answered.

SYSTEM

3M Model 515 TEG

(Thermoelectric)Convertor + battery

25 watts

116

FIRST COST

$ 1462.

ANNUAL COST

$ 496. (fuel deliveredat$ 16.80 per bbl)

Solar array, limiter, battery; $ 450030 watts cont. 5 year life, 7% deprec.

$ 1215.

Tyco/Winston array at $ 5/peakwatt, limiter and battery

TEG with fuel at a deliveredcost of $ 40 per bbl

$ 800 $ 190.$ 204.$ 127.

$ 635.

(7%) 5 Y

(10%) 5 Y(10%) 10 Y

Spark ignition ICE

Stirling Cycle Engine

Ormat turbine

IT's HARD TO BEAT THE ICE.

$ 96

$ 400

$ $ 60 with kerosineat$ 0.40 per gallon

$ 96 with kerosineat$ 1.CO per gallon

$ 126.00

$ 160.