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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
,.,
セN "
,. , L
セN '.
",
, -,
,;,
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'It
<> 't:- セ L G セ L セ
.- ,, ..-..セセ ','....,,!
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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 ,
'/\
_ 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 $",.""" O.OS/YEAR'"40 + \ /' ,,-'" t 2000",""" m","" a
.""..."""
30 t \ ./' .""."""",,--"""--
",."""--.---""",.
K セ M M | セ +100020 \.
O.OS/YEAR
4030
--20
YEARS10
o-I Io I I I I 0
TWO PROJECTIONS - U.S. SILICON AND PHOTOVOLTAICSILICON PRODUCTION, 1975 - 2000
a.セ
10 }J
102 }J
103,..
E.RALPH(1 )
-", """" セ e A (2)""' ..................... -- "' .......
-- TOTAL SIC SILICON
-- PEPS SI LICON
- - - SOLAR CELL THICKNESS ( J.I )
103
10 , r I I I I I I 10°JJ1975 1980 1985 1990 1995 2000
102
104
METRIC TON S OF105+SEMICONDUCTOR
SILICON PER YEAR
t
bl
1989198519801975
I // / ....• I .I
,., .. ,. I T .I
.I
.:. , :
/ .I /
j ,/ .
;0/ / .......
. .. .II :
if' ' .
IV: '1
/ :',I •
// .':' I. .V /.: I
/.: f/
..'.
fl
I / I.' f.
.'/I :l I. I
I.. ,
:'1 I• /1 IIj
,. . .I. I
.' . if I _._-- lLINDMEYER-
I . I..I FEA "ACCELERATED".. .. I/ . I -_.._- ..- F EA "BUSINESS AS,
/. I; . . I USUAL ...I .: / -
I ............. F .ELDRIDGE. .: / I/: . I ----- R.BLlEDENJ •. / I. .l: /..' ..
/I VARIOUS FORECASTS OF ACCUMU-I.LATED PEAK POWER GENERATION:-1 ..
I IN THE U.S. BY PHOTOVOLTAIC. .I/1 . CONVERSION. ..
.: I I. .' I,.1. .. .
.Ii
/.I..0.1
10
1.0
100
ACCUtv1ULATED PEAK POWER [MWe]MWe
1000
63
1GW. -+----.-- -+----1-'ANNUA'L MARKE セ V.s. ----l: セvN SYSTEM COST - A GUESS
I :I 1I I
I100 MW MエMMMMKMMセMNNNNlMMMMMMMエMMMエMMMMMKMMMMMMMQQMM
r'OMW , I, I, If- IUJ 'I::.::: ,a::« lMWセ I'--'
I ,
« I ,
:::> I ,z I 'z I "セ I100kW
COST RANGE OFCURRENT RV.TECHNOLOGIES
•104 105 106
SYSTEM COST ($ 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
.."\
I \. :
セ r セN
-: ' 'f セ G N B
,A • I. ' .,' セ ••••••
u
i BBGセ t 1 ヲGイNセQQ "'.'-'.; ; '. ,,,< ,:" ,'.'. I... ; - I
IIセ
fセvN
'.:セNZ
QセGM|エj\ C'· I. I.- . \
<.... ._._·w._· i...1 k\".' _,_._.._.__.u__..... _ .• セ ⦅ N B B ..••:.O'
QPGセ 1:;::
10k\V+--
Z<..(
f--LU
( ZLセI
セ.' ._---;: ..
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
kwepl YEAR SOLAR CELL PRODUCTION
r
j
jUセ -セ I I l"i M セ
Q P T セ ----I I セ 1----
G セ i セ I , I I I I I I I I YEAR1980 1985
QPSセ MMMMMエiMMMMMTiiiャセセ I I I
68 ,';;M. • .... A セ ....
Bestell-Nr. 667155, Nr. 365 %....OE .. GERM.NY
6j
5I
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4
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3
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セセ COPYRIGHT SCHLEICHER & SCHULL, 3352 EINBECK F;1Lセ ':II'
1 2 3 4 5 6,I
3 4 5 6 7
S/ /; C. セセ '"\ (-.·C )2
VI , h·......, l ... (.:::..,-oI Lセ :. tJ
lMMMKMMMMMMMMQMMMMKMセ⦅エ⦅MNM⦅K⦅M⦅エ⦅⦅エMK⦅Mャ⦅MヲNAMMMMMMMエiMMMMMェMiMM⦅エMMKKMAM
8 9 10 2 3 4.::' 6
I ." 1D ..:: .t'..-I'•. ヲLセセLZNャN[⦅[Nセ セI V
Zunahme in % 0 g 5 セ g g ----. ue.... u..... t--s セ 。 ャ A ャ セ ッ 0 Abnahme in %
01UJ
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5 6 7 89104326 7 8 9104325 6 7 89104321 2 3 4 5 6 7 8 9 10
セ 0,:- ' ! ' +- I I I 1+1-;-' I 'I I II I I I セ , I 'I I I 1 I II セ L ' 1 'I I I I I III" '., I I I I I I I I"'" , , I .. I I ' I 1""'. 1--":"'" ;. . c••• j': 1':: '-1: ::;t -+ I II 'I'j.'·;';:-:-'j :.: ZGセセヲNcMbiZZZKZZᄋ ;..;.:-1 ZMセZャG - :r- GイセhZZBBBGZG]M :-..:": BGZBZセセMMGNLMG .;.-::-:-: -'=:.-:: Mセ「NZ mIl エMNMMセ -:::.. ._.. ,,--: .. ::...;:::, NNZ」MZセイ l'.lt! .h
I Nセ .. , 'J' ., '--'j-I I . ,.---.. "' G N セ ...-•. セ N "-" .;. . t セM , セMMM -- -.•... -- -- - I·t·· ··-·c····--···---J"-" '--'''' t I,.. '" .... I ...., ,. -- . ,'. -.. .. _,::: ·1· . - セ .... _.- ..-...... --" -.". - t-+ - "r- =. セ ] ..'-' .. -. " ., セ ,- J ' - .: セ Z - セMZMGZZ .. セN MセB --; -- 1 ! ; • LGセN : : セZ '--:-:.:.:. =:: 0: .:.. + - I .:.:..• -. セ Z [ N ..••.. ::: -;::::;: ::: i j . ':I--:-:=:::': セNZZ -:-,.; :.:;. ;-::: '.::I·l "1' -:t:Tl _L . I· ", .... '11'1.1 .. ······-··-- .... --I Ll -._--... ···1· セ N N N i セ h b j .-- .. --:."-' '.-. "r' 111":r
M K M M セ セ ",-_.'--- - セセK[hエNhゥ セNZ '-: .. "-> セ N G セ ャ Z セ N -',: t ; ,--_. M M セ N セ セ Z _:." ',_ M セ セ N ⦅ セ Z T - セ セ 1---' = -- -: :--:-: Nェセ[ .'. :i 1I' ,. .•. .. .. , . I . I ,.... .. I .. -- 1 I, -.-. '"1--''' ᄋ セ [ エ Z M ᄋ ᄋ --+.... 1.•·tJ t. .. ·----1 -- . 1"- -." .. i ' • r >'· '! .o .. j I' :1 : •• -' ':. ,.' -" :', J : I r __ - -:...- ZセMMZNセ MGZGZセセセZG _ .• :.: t _'..- j. セ _--::":1.:•. :'2_ -= __: ZセZ lZセN : '. I _ ! : i _セ i-·-:- --..[J···1-----:- ---+ jl 1;IJ<-;-;-J,J;---- ,--! -;:r .:--- セ \---'-'--qcL. \- -l-i-+ セWMZZZ]KZM]MQMZMMMェGMZM イMMZMZMセN --:-:-: + I=+- 'w' I LL[-:---::::::-t--. iM[MNMM[MエMMZM|セNZMイNMMMjN セM 41 1Lttt·, . . セN .. ' . -W Ii ItI ' { • - I " ... I .. ,,' . , I I I 1 .•. . ,..... . '" ',: I :: :. .. . I t 1I l' .- .;C;·:-·I ". .. •. ... . j I 'I· j .L' (\- .i--:..i.c.:-·.:....·:.....·i-···- i .+ J;.• '::,' . .,..J...:....:. . •- •. + • セ QQQセGᄋ[NNNエNZNNNNNZNZNNェNNNNNZNZNNゥMZセN⦅ZNNZNNNZNiMMGMMMゥNエ II _._..+.:;,..:,' ::., セG .... LL,.I.t ,_
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t--- ---.--- L._ "0 -- :>: t r t - セ \' -, GMMGGZGGZGGGKMM]MMZGGGGイMGGMMMiMMXMMセセゥセエ '1" tt-:---.----l--1---- セ N ⦅ M _ ..+.- G M セ G ᄋ .... I "t-'i-I . ! セ _ :: :::' i ! ,\ II i セZ[GZA .: ; i :. : セ セ :: . r :' I . : ! i! : ;'. : I '. . .: .j .; ;:;:: i: .: f i ' II セ
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,.. I ._ ....- -. I 1-'- ::.. .:.. r. = t·+·t--l-r' ",'" MMMNMMMMNェNNZMMQMMMMMMMlイMイMltᄋMGNNLNNNQNᄋセMZZZZNNZNNNNNMエMMMMZNZNNZャMMN MMMヲMMiMBGイ[NNNNセNャN -- "1 I :. -::-;.. '1'::1 I ᄋセᄋ .. I.·I. B G セ B Z i i B '.:'''1;::'';.:' ';::1" "'I'lt:'I . I , -:- = ]MNセN ..., . I ' . '. _. I . . . . . . 1 I' I • I I . .. - ... I ' .. I· . . ;:0:' :1-, '...., ' "r I · I:"='-'J< - セ セZZZ C .1 1: 'I'il' LNセMZMセェNN[NMNQエMZMᄋQQZN ;"""':rr'ti1t l
l ::....:.,:l-..:..::ll}!t;-·I=·;·: セゥイM[NNNエ ill' ., - - - .- セ N - - 1 セ rt 1 • .,. - • " t j" r .... .,. ... , .... ,"\ ,. '1· GセN - -.. '" ,-:... セ B , ", . .. .. I .. , . . .., II'" .-. .. -...... CJ· I' .I j -..:;:: -: - r: -I セM -. t If; , I .: . .:. '. 'I' I 't: セ :..: ::: : .. , : i . : :.. セ " :' \.,
t- __._. ._.1-__...;::: :-. セ ::0.- -.....::: .::::.\- ..,JT NiNセM⦅エ⦅MMセ -l.:_ -i --rtf-'l-t-+-L ..- t 1----1-- セ "d,",_•• _ -I'. : .- -'" -- - 1- \ I I • f • • I .. , - j -' • -.:: • セZM 1 1 l I I! ..:':''': I :.: t ' ,.:.: . :. . .. r. ::;.. """: ;r;' セ : I t i ,1 ., • = -: -' ." I . ., I \ ., l' " I I r- I I 1 , ..• - ,_. I' . ," - .... , セ ..... _.1 . t ' , , ,
1 I ; . :;::;- > エQエセZi[LNj ':--1": ゥMZᄋᄋMMエMᄋM⦅ᄋᄋエZMMᄋiMᄋᄋエZiNセエャGiiGMMZセGZ __ NMMGMGゥGZ[「ᄋMセ .. NZエLMセZ[NZZZiZセBBゥ[Q '.r I I • , • I I .III .. .. t' I""" .,., .•. I -. " , ,..... '-A .' ""! :0 .:; セ 'I . . , . ' .. .. .. t • II ,'" .. ,. ."'. , ,', ·::i t·,t I :: -;. - _ j.:1. ". .:. ,J::. ,t セ • セN •• _ :., .: I. " .. ', l .. !., , •...• ------.,-•• - .:... Mセ .- -l•• ,1····'1---·---------.----t... セQᄋェᄋェゥNエM[NQMMjMMMlMMMNセ .".. セ、LNL .. , .... _I" ""':; til, l'j' ';!.': ," ·1' ',:1' ::'. . , .... ' , ....i i-" "'tl . :::- _; I! ! I ; . __ :. :- t: ':. -+ : i i l- セ J: 1 i ._: .'- . . . セL : 1 : .; セ .! L セ I "'1 I セL ! i } ;I I.. . """ 1.- Z r' セェj Ht I GMBGセセQMGM ,_. ·I.•:t セ M L I. ·-t t 'J 'K' ,.1 1·:--·-- ..... 1 -.-- 1 •._. -1- _H セ N - I I.·''I I' ' セ I' '1' .... ,.. r.._ Illr,t.- ... セ セ .. , エGᄋᄋᄋᄋGᄋBBBBGiセGiB• • 1;:....-. - i' セ - • . I - I· . l, t t '1 ,--...... .. ".. . ! -, .• • • セ
I .1 .:: - ,. セ ] M Z M セ ';J ,,_ .. ,I .. ,! t -, 't-: ;-- セ N Z Z B ::.::1' :;. ... : .. エ Z Z T セ Z!;jl lセ -to ---------1··--'-·· -- - I f I - .L li----- ----+----1 --+-'-+T- - .1 セ ·1-m-.=!·... · ,,1 ..\ I .: ·.··1.. ! セ セ m:li1t: ;·::t.. '.J ,.:;. セ ゥ Z ャ ゥ f,! i1j ZZNセZ [セZMセ[セゥAᄋ[Zᄋ GZMセZANセNセNセZZセGAG[ZZ .. :[. f' •. 1···· ,..., t,-,·",I·L.. --t----h.. ᄋLᄋMMiMMMiᄋᄋᄋiNjセLAョNエエ} QェセMM⦅ᄋᄋセエᄋM」MQMMGᄋGセᄋLBMiNャイャMᄋl ' セ ; :1: I,' ',.;' ;'. :: .. I [1'1 :.' I.:r::;:: ':;c"-"{'I"v' jI I ' . . - Z, I Nセ ,I . I .. ,..... ,. I ., - '. . .. ' . .' セBBI • •• • •• -. ., • f- セ • • • • , • f •• t'... • • I I ,,. r' - - .. --.. --.- - - .- +--t '-. t 1 -t·+- -_.. --- .:.1'4- .-.- ,. --to_L._ -··L-+l' -- ---1.-. r----··· ., .' -I'": Til. r .: I . I .: , セ セ i j : } j セLA ;':' 1: .: j" i I· セ N 1. . : ! 1 ' i; i' : ; -: . :..:. .' J;;:I ; : セ セ t セNセZ :;; i 2.; ; ': : I
セI... _L.. ,. -. -' l' "'1- .!.!-.---t---t-:·-..,·-I·-·-.. ··· -, lセiMlNMKイセサ ..--·-·r.-..,.._+.--r.-.J-+-;.; GQセQQ ItlUI !' - ::-:, , ' j セ .: " :-;- -: .. :'., .-. I '.. I J' " Jf' .: - : : :I . , セ . , c: : .1 .."., - . ". ;• •. • - I" ., L .-j _- I" , , ..• , .. セ ,-" 111·
- --.M M M i Z M セ M セ B G [ -= ::: iエ⦅セ -, ᄋ エ エ イ セ M M Z B セ M : MセN セZNZ . セ _ : _ _ j⦅セ KNエセエセ .-t - セ BLNLエMZMMZMエMMZMZエMセZ セ ..... セ セエ r-j-.l ' _
• .", ::: R Ilf t++" . r ," '--1'" ··.. I····J' ャ セ イ j G n" ョ⦅セiGiGャャイャ
セ [--.-- Mセ .. -i: . ;..- - ᄋエᄋᄋiMセセᄋM GjゥゥKエᄋセNNZNNNZ セLMM[L :;:. -:1"Z セ N セ r-:·:':' --' -' U 1セ -:4__: +k-4';' [BG[⦅i」セBZ セ ZエエNセZNA セ Ii :.:.' t "lUll--- I . I I ,. - • ... ... . . .. . . :-i ' ... .. .. . ... ., .. " .. ... I " ..,.,. 'II '
.. , • I • • "1 "'-' ..•.• - •.• f 'll' i l '.... . . ."'i'" ... ''! I . 1
- セMセMMセセセMAMセ ::: セMMZ ,-1 t M]セMZNM[セZセ[セjセZNMKセ ⦅セ^MセTエMZMセ j -.-_.: I セ⦅セGZ NセセN ZZQセNセセセZセN セセセセNゥ[ゥlイZLZGM. . I '" .., - I I 1 I I '" \- . ·-'1' I t I II ' , <, ' ••• , I ••••• ,. " •.,., ''''''' 1 •• •
r •.. : .. セ Z N M N Z N セ - ::::: = 1-·jlr'H1t,t\11 :.:.:r'-:I"p, M[セBZGZィGMZᄋ[MヲZ⦅ᄋiGゥuZiᄋヲャZ I GセNZjェセLャ」BゥNLヲLbᄋGZ[LBゥウャLLZエャt' I . I :. 2. ±: -= ..:: := .:::: t,. [ セ Z B L [ L !.-,:-.; .: .. :.•..;;. : 1 , I I,ll:': ::: : f:-·,.; BセNGゥZB '-"'j l.i-'-3 ,r: ;.., .-.-.- - ::. ::: ., I. セ . . . . . .. , . ..". , I . 1 . . I. ..I ...... ::J:;? I.,
.'-.-.----.- M M セ M M J - - - - - z tt T KLMMNセ⦅N __ I::::i__ M M セ N セ N M M M M ..-._- - セMBGMMᄋiエ ......Bᄋセ1 " . _ -:::: セ _,- I I . -. , NMNセ I' " , f· - •••• 1 ", l' ,.-, I , I セ I I
II . . T· i ;; セ セ = :: - :;:;.::- t! L. ltl-j'tt2";_::lOOi CJ' C' .,.' Z G セ エ ;-T j I jI c Z M [ N セ セ f: ;: ::ttLJ; :1: ,l :tt< 'il ; ! t-'! ! i
lNl j I-I '. :..... :-i:' .. , ;:: ;, -4-4-44l'-f 'I tZセZZ f:--:: セ セ Z B B B A Z Z Z N =:: -:-::.'1 ; t'[l t,t .:...-=-: .-:: ·l:l-::· .. NZZZZイセ :--:. -'I-I' Gセヲ t, .
, ".<. - iセ ,I. I .... - . -..... 0+ -., rlll:l···-- '·!·:'.jc::·t·,· +,. III;. : .... ··..,.... --1-....:.;......-1· Gtセ t- 1'1 I I i r I I , . , ,...... . ..+. ','- . . . --r-f--tt' 1 . :' ᄋ エ ᄋ セ Q セ N ャ N エ Z N N セ , -i .
セMMM[M .._----_.+--+--+ : l--t-rH-t- I I I I I I t--r+H-' I I I +-+++-+++-----+--+ I I ! I NェセKKKセ2 :3 4 5 6 7 e 9 10 2 3 4 5 6 7 8 9 10 2 3. 4 5 6 7 8 9 10 2 3 4 5 6 7 8 9 10
7 . セI セ ( 1. i CllP,,.i,;c.l 'f SCHI.EICIIU< ,'I. SCHUll. 33b2 [INn!" CK U S,,:;lell·Nr. 667054. Nr. 3139',: Ii ""l'l'tI """"tI, E,ne Achs" logdr \),,,,,"1 von I blS in 000. E,nhelt 62.5 mrn, UIl' and."eIn nll" m,t p イ P W L L B エ ュ セ i b ウ ャ 。 「
"lUESTIMATED $/ kwep PHOTOVOLTAIC POWERSYSTEM COSTS FOR U.S.RESIDENTIAL APPLICATION
,$/ kwep
500
400
300
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.
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