TP# 20: 02/85
UNDERSTANDING
SOLAR WATER PUMPS
by
C. J. Swet
Technical Reviewers:
Paul E. Dorvel
John D. Furber
Daniel Ingold
Published by:
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PREFACE
This paper is one of a series published by Volunteers in
Technical
Assistance to provide an introduction to specific
state-of-the-art
technologies of interest to people in developing countries.
The papers are intended to be used as guidelines to help
people choose technologies that are suitable to their
situations.
They are not intended to provide construction or
implementation
details. People are
urged to contact VITA or a similar organization
for further information and technical assistance if they
find that a particular technology seems to meet their needs.
The papers in the series were written, reviewed, and
illustrated
almost entirely by VITA Volunteer technical experts on a
purely
voluntary basis.
Some 500 volunteers were involved in the production
of the first 100 titles issued, contributing approximately
5,000 hours of their time.
VITA staff included Maria Giannuzzi
and Leslie Gottschalk as editors, Julie Berman handling
typesetting
and layout, and Margaret Crouch as project manager.
C.J. Swet, the author of this paper, has a background in
engineering,
and is a consultant in solar and other "gentle"
technologies,
with special emphasis on energy storage.
He has 20 years
experience in the field of solar energy, and has consulted
on
solar energy and other appropriate technology projects in
developing
countries. He has
published several papers on solar energy
and other energy related topics.
Reviewers Paul E. Dorvel, John
D. Furber, and Daniel Ingold are also experts in the field
of
solar energy. Paul
E. Dorvel is currently Associate Principal
Engineer in the Power Systems Division of the International
Engineering Company.
He has over seven years experience in Africa
doing market research and field engineering for solar
micropump
irrigation systems.
John D. Furber is President of Pleasant
Valley Software Corporation and Starlight Energy
Technology. He
frequently lectures and consults overseas on solar energy
technologies.
Daniel Ingold is a biophysicist by training and a
research engineer at Appropriate Technology Corporation.
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working on technical problems in developing countries.
VITA offers
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For more information about VITA services in general, or the
technology presented in this paper, contact VITA at 1815
North
Lynn Street, Suite 200, Arlington, Virginia 22209 USA.
UNDERSTANDING SOLAR WATER PUMPS
By
VITA Volunteer C.J. Swet
I. INTRODUCTION
This paper examines water pumping systems that use solar
radiation
as a direct source of energy.
We look primarily at small-scale
rural applications in the Third World, where the potential
benefits are greatest and the near-term economics seem most
favorable. Two generic
technical approaches for solar water
pumping systems will be examined:
(1) thermodynamic (in which
the radiant energy is first converted to heat); and (2)
photovoltaic
(in which it is first converted to electricity).
Since
photovoltaic technology is more mature, it is used for
economic
comparisons with other methods of pumping water.
Our treatment
of this complex subject is necessarily cursory; the aim is
to
provide prospective users with sufficient insight to
determine
whether solar water pumping is a plausible option for their
specific situation, and to furnish a guide for further
investigation.(*)
HISTORY
The history of thermodynamic solar water pumping technology
goes
back nearly four hundred years, when Solomon deCaux in
France
raised water for a fountain by the expansion of solar-heated
air.
By the beginning of this century, many of the currently
competing
design concepts had already been explored, and several
promising
attempts at commercialization were under way when activity
subsided
due to the advent of the internal combustion engine and
cheap commercial fuels.
Much of this development had been aimed
at relatively large-scale applications.
It was not until the
resurgence of interest in solar energy caused by the
1973-1974
oil embargo that greater attention began to be directed at
small-scale
rural applications in developing countries.
(*) Of particular interest to the serious reader in this
field is
the the definitive and comprehensive work done in
conjunction
with the United Nations Development Programme/World Bank
Small-Scale
Solar-powered Irrigation Pumping Systems Project by Sir
William Halcrow & Partners and the Intermediate
Technology Development
Group, Ltd. The most
important reference for the prospective
solar pump user is Handbook on Solar Water Pumping (see
bibliography).
In contrast, the development of photovoltaic water pumps has
heavily emphasized small-scale rural applications since the
1960s. While both of
these technical approaches continue to
mature, neither can yet be judged inherently superior.
Most of
the recent efforts, however, have concentrated on
photovoltaic
systems and a majority of solar pump field operating
experience
has been with photovoltaic installations.
NEEDS SERVED BY THE TECHNOLOGY
Solar water pumps may be used for irrigation, community
water
supply, livestock watering, and in various industrial
processes.
In principle they may be used virtually anywhere, but the
most
compelling needs and opportunities are found in the
fuel-poor but
sun-rich rural areas of the Third World.
Solar pumps may also be
almost any size, but most small farms, villages, and animal
herds
in developing countries require hydraulic output power of
less
than a kilowatt.
Many of these potential users are too far from
an electrical grid to economically tap that source of power,
and
engine-driven pumping tends to be prohibitevely expensive as
well
as unreliable due to the high cost of purchased fuel and
insufficient
maintenance and repair capabilities.
Developing countries increasingly require less costly and
more
reliable methods of pumping water that do not rely on
commercial
energy supplies.
Solar water pumping is one of several potentially
satisfactory alternatives, which also include wind, water,
biomass, animal, and human power.
Greater use of irrigation is clearly needed to increase the
yield
from existing cultivated land and to permit cultivation of
presently
marginal or unusable land.
Nearly all this additional
irrigation will have to use pumped water, since most of the
available sources of gravity-fed water are already fully
exploited.
In Third World countries, most irrigated land is in family
plots of less than four hectares, a large proportion of
these
being under one hectare.
This practice can be expected to extend
to lands not yet under cultivation, since small plots have
been
found to be more productive than large farming units in
terms of
yield per hectare although more demanding in terms of labor
input.
Daily demand for pumped irrigation water varies widely depending
on the season, crop, stage of growth, region, method of
water
distribution, and water management effectiveness, with
maximum
values ranging from about 20 to 120 cubic meters per hectare
per
day. Water sources
include ground water from open (dug) wells or
boreholes that are surface water from rivers, ponds, or
canals,
and typically at depths of two to 10 meters below ground
level.
Irrigation water is seldom extracted from depths greater
than 10
meters because the value of its benefits is seldom high
enough to
justify the extra cost of deeper wells and additional
pumping
energy. To be
economically feasible for agricultural applications,
the cost of water delivered must be less than the value of
the benefits obtained through use of the irrigation water,
either
through improved yields or by enabling more crops to be
grown per
year. In 1982 a
global norm for the cost ceiling for water delivered
to the field (not to the crop) was approximately US$0.06
per cubic meter, although clearly the actual figure in a
particular
situation will depend on the crops grown, the field
application
efficiency, and market prices.
If 60 percent of the pumped
water is used by the crop itself (a fairly typical condition
for
earth furrows), the cost ceiling for that water would be
US$0.10
per cubic meter.
Most villages in developing countries have fewer than 1,500
inhabitants,
and in many of those villages the per capita water
consumption is far less than the 40 or more liters per day
deemed
desirable from a health standpoint.
A common reason for this low
consumption is that all the water is drawn from a single
well,
resulting in lines, and in larger villages, the need to
carry
water considerable distances.
Although multiple dispersed wells
will alleviate these problems, polluted sources become more
difficult
to avoid. Ground
water is usually extracted from depths
of 30 meters or more because its value for human consumption
is
much greater than that for irrigation; water sellers in
developing
countries often command a price equivalent to more than
US$3.00 per cubic meter for 10 to 30 liters per day.
For this
application, the economic feasibility of solar water pumping
is
much less a factor than its competitive position relative to
other methods of mechanized pumping.
For livestock-watering in remote areas, daily demand per
head
varies widely depending on breed and type of forage; about
40
liters is fairly representative for dairy cattle.
In recent
years many engine-driven borehole pumps have been installed
for
this purpose, pumping from depths as low as 30 meters.
Thus, a
herd of cattle and a village of the same population may have
comparable pumping power requirements.
However, for this application
it is often desirable to have multiple dispersed pumps in
order to minimize overgrazing near each watering place.
These
considerations accent the need for pumps that can operate
reliably
when unattended for long periods of time, and that do not
require secure fuel stores at each watering place.
II. OPERATING
PRINCIPLES
Although thermodynamic and photovoltaic solar water pumping
systems are conceptually similar in that both are powered
directly by solar radiation, their operating principles are
quite
different. The
following discussion highlights the distinctive
features of these systems.(*)
THERMODYNAMIC SYSTEMS
All thermodynamic systems use a solar collector to convert
solar
radiation to heat and a heat engine to convert the heat to
mechanical
power for pumping.
In heat engines a fluid or gas absorbs
heat at a higher temperature, which causes it to expand; it
then contracts upon removal of the heat at a lower
temperature.
This expansion and contraction is harnessed to move a
reciprocating
piston in a cylinder, or it can expand against a turbine
wheel.
Figure 1 illustrates the basic energy flows, showing
qualitatively
31p05.gif (600x600)
the necessary temperature differential across the heat
engine
and the unavoidable losses associated with each stage of the
process. Of the two
indicated temperatures, the lower one cannot
be lower than that of the pumped water to which the unusable
degraded heat is typically rejected, while the upper one is
largely controlled by the type of collector.
Increasing the
upper temperature (within practical limits) raises the
overall
system efficiency and reduces the required collector size,
but
usually at the cost of greater complexity or more expensive
materials. This
broadly characterized conceptual approach can
have many different embodiments, with various types and
combinations
of collectors, working fluids, heat engine cycles, engines,
and pumps, as discussed in Section III.
PHOTOVOLTAIC SYSTEMS
These systems exploit the photovoltaic effect to convert
solar
radiation to direct current electricity, which powers a
motor-driven
pump. A basic
photovoltaic system layout is shown in
Figure 2.
Photovoltaic conversion occurs when light falls upon a
31p06.gif (600x600)
thin, flat material called a solar cell.
One side of the cell
becomes electrically positive, and the other electrically
negative.
This is a solid-state, electronic effect.
Like a transistor,
the solar cell has no moving parts except electrons.
(*) Detailed explanations of these operating principles can
be found
in the publications listed in the bibliography.
As long as light falls on the cell, the electrons flow as an
electrical current through an external circuit containing
the
motor. Individual
solar cells are connected in series strings to
obtain the desired output voltage.
Series strings can be connected
in parallel to obtain the desired output current of a
module. Several
modules are then interconnected and mounted.
Photovoltaic array output current and power--to the extent
voltage
is constant--vary linearly with solar irradiance.
Efficiency
and power output decrease with increasing cell temperature on
the
order of 0.5 percent per [degrees] C above 28 [degrees] C.
Figure 3 shows the performance characteristics of the
components
31p08.gif (600x600)
of a typical photovoltaic pumping system, illustrating the
importance
of proper matching of the electical source and the hydraulic
load over a range of operating conditions.
Some optional
components and configurations of these systems are discussed
in
Section III.
III. DESIGN
VARIATIONS
THERMODYNAMIC SYSTEMS
Most of the small-scale systems that have been developed beyond
the prototype stage use Rankine cycles similar to the one
shown
schematically in Figure 4, with organic working fluids such
as
31p09.gif (600x600)
Freon 11 and slow-speed reciprocating engines that directly
drive
piston pumps. Many
developing regions are familiar with Rankine
systems because of experience with steam engines.
Organic working
fluids can produce higher heat-to-work conversion
efficiencies
than steam at temperatures up to their stability limit of
about 150 [degrees] C, but extreme care must be taken to
ensure zero leakage
since very small amounts incapacitate the system and
recharging
is difficult in the field.
A reciprocating engine is virtually
the only choice,
since turbines and rotary expanders are
excessively expensive in the small sizes of interest.
Slow-speed
reciprocating (piston) pumps tend to be more efficient than
conventional high-speed centrifugal pumps at heads greater
than
about 10 meters, although single stage centrifugal pumps
(which
are easy to make) are well suited for very low-head irrigation.
The system depicted in Figure 4, which was designed by a
Finnish
company, has a trough-type concentrating solar collector
that
follows the sun by rotating about a horizontal north-south
axis.
Sun following is automatic, powered by the shifting weight
of
solar-heated Freon and controlled by a sun shade mounted on
the
collector, but the orientation must be reset manually each
day.
The collector has a 12 square meter aperture, occupies 16.5
square meters of ground space, and weighs 170
kilograms. All of
the other above-ground components occupy a 0.4 cubic meter
volume
and weigh about 50 kilograms.
Aluminum is used extensively for
both weight reduction and corrosion resistance.
At a Freon
temperature of 107 [degrees] C the reported delivery rate is
about two
liters per second (roughly equivalent to 40 cubic meters per
day
if the pump operates eight hours) against a total pumping
head of
14 meters. The
reported rate is nearly five liters per second
(100 cubic meters per day) against a head of three meters.
The
above-ground pump location limits the use of this system to
shallow wells or surface water sources involving suction
lifts no
greater than about eight meters.
A somewhat similar system from West Germany has about 40
square
meters of stationary flat plate collectors that can heat the
Freon 11 working fluid to about 90 [degrees] C.
Its pump can be located
below grade and is adaptable to wells up to 60 meters deep.
Preliminary testing in India indicates a delivery rate of 40
cubic meters per day against total pumping heads of 15 to 20
meters. The pump is
sized to permit greater output when larger
collectors are used.
Water (steam) has some important advantages as a Rankine
cycle
working fluid. It
can be used at higher temperatures than are
possible with organic fluids, to achieve higher
efficiencies.
Also, the consequences of leakage are far less severe.
An Indian
firm has developed a 2-kilowatt uniflow reciprocating steam
engine powered by a glass strip reflector trough collector.
However, higher temperatures require greater optical and
tracking
precision, which increases the cost per unit collector area
and
tends to offset the size reduction made possible by improved
efficiency. The
economic competitiveness of high-temperature
Rankine cycle solar pumps is still a under contention.
Stirling cycle heat engines offer perhaps the most promising
means of exploiting the very high temperatures (over 500
[degrees] C) that
can be obtained with point focusing collectors, such as
parabolic
dish reflectors.
Sunpower Inc. in the United States has developed
a free piston Stirling engine with an integral diaphram
pump,
using helium as the working fluid.
In tests by the manufacturer
with a simulated solar thermal input of 1 kilowatt
(corresponding
to the output of a dish approximately 1.4 meters in
diameter),
the Stirling engine delivered 2 liters per second at 560
[degrees] C
against a head of four meters.
At its present stage of development,
however, it is easily damaged, and test results have been
disappointing.
Another promising Stirling engine pump is the
"Fluidyne" liquid piston system being developed by
another Indian
company, but no solar version has yet been demonstrated.
Many other technically intriguing and potentially useful
systems
have been or are being developed, including:
1.
smaller organic Rankine systems;
2.
very small (about 25 watts) steam Rankine
systems;
3.
an organic vapor liquid piston pump;
4.
a heated air liquid piston pump;
5.
a fluid overbalancing rocking beam engine
pump; and
6.
various solid state systems based on
"memory metals,"
polymers,
and the differential expansion of bimetal
strips.
Some of these systems have become commercially available,
but it
must be emphasized that none of them (or of the other
concepts
described above) is known to have successfully undergone the
extensive testing under field conditions that characterize a
mature product.
Ability to manufacture and repair such technology often depends
on the region. The
several systems presently being developed in
India presumably would be manufactured there, and an Indian
affiliate of the West German company is evaluating the
possibility
of locally producing all or part of the German system.
This
does not mean, though, that these systems of Indian design
could
or would be manufactured elsewhere in the Third World.
Supporting
frames, conventional heat exchangers, and some types of
collectors could be made and repaired in many developing
countries,
but reciprocating engines and piston pumps of high
efficiency
call for close tolerances that may not be readily achievable
with available skills and equipment.
PHOTOVOLTAIC SYSTEMS
A number of types and sizes of photovoltaic systems are
available
commercially, in various stages of product development, that
meet
the range of pumping needs outlined in Section I.
The significant
design variations of these systems are fewer and more easily
presented than those of the relatively immature
thermodynamic
approach. These
variations center mainly on:
1.
the choice of solar cell material;
2.
the choice between stationary and
sun-following solar
arrays;
3.
the choice between planar and concentrating
solar
arrays;
4.
the type of electric motor;
5.
the type of pump; and
6.
the method of source/load matching.
All commercially available systems use crystalline silicon
solar
cells, of either the single crystal or polycrystal
type. Other
types of solar cells, which may be less expensive, are under
development. These
use thin films of semiconductor materials,
such as amorphous silicon or cadmium sulfide.
Currently available
solar arrays produce roughly 100 watts per square meter
under the
most favorable conditions.
Specific pumping needs do not influence
the choice among these competing designs.
In most systems the solar arrays have a fixed orientation;
they
are tilted permanently toward the equator at an angle that
maximizes
energy collection during the season of maximum demand (or
for the year if demand is fairly constant).
This is the simplest
and most affordable configuration, but not necessarily the
least-expensive
in terms of cost per unit of delivered water.
At
slightly greater first cost and complexity, the orientation
may
be manually adjusted several times during the day, thereby
increasing
the daily output by up to 30 percent.
This tends to be
cost effective provided that manual labor is available and
is
inexpensive for highly seasonal irrigation
applications. If the
system is used over most of the year, a fully automatic
tracking
device may be justified.
Although such systems have not yet
demonstrated sufficient reliability under field conditions,
some
recent field operating experience with gravity-driven Freon
trackers on pumping systems has been encouraging.(*)
As long as solar cells remain the dominant cost item there
is an
incentive to reduce the required area not only through sun
following
but also through concentrating the intercepted solar
radiation. The cost
decrease due to further cell area reduction
tends to be offset by the added cost of concentrating optics
and
the need for better cooling of the cells and more precise
tracking.
If solar cell prices diminish as predicted, the incentive
will become much less compelling.
Permanent magnet direct current motors are the most commonly
used
pump drivers for small-scale systems.
Alternating current motors
cost less but are much less efficient in the sizes of
interest.
Linear actuators have been used to drive piston pumps, but
the
concept requires considerably more development.
Many of the
direct current motors in current use are of the conventional
brush type, which is efficient but poorly suited for
submerged
operation and needs brush replacement after every few
thousand
(*) See for example Dankoff, W., "Pumping
Water," Solar Age, February
1984, pp. 29-35.
hours of use.
Electronically-commutated brushless direct current
motors are finding favor because they require less maintenance
and are more readily adapted to submerged operation,
although
they are slightly less efficient.
Single-stage centrifugal pumps are frequently used when the
total
pumping head is less than 10 meters, and are either
self-priming
or (if the suction lift is too great) submerged.
With open wells
or surface water sources, these pumps and the motors can
float,
thereby minimizing the suction lift.
For higher heads, either
multistage centrifugal or positive displacement (piston or
progressive
cavity) types are most efficient.
If the pump is above
ground or floating, it usually is closely coupled to the
motor;
if submerged, the pump may either be closely coupled to a
submersible
motor or driven by a vertical shaft.
Positive displacement
pumps ordinarily are submerged except in cases where the
lift is
small but the total pumping head is high.
Single-stage centrifugal pumps can be made with
head-capacity
characteristics that fairly closely the solar array
current-voltage
characteristics, so that the array can operate at near-peak
efficiency over a wide range of operating conditions.
This
matching cannot take place with multistage centrifugal or
positive
displacement pumps.
For systems that are not inherently
compatible in this respect, it is possible to install an
electronic
impedance matching device between the array and the motor
that will automatically optimize the load on the array.
These
devices, called maximum power point trackers or maximum
power
controllers (MPCs), will increase daily pumped output and
will
allow pumping to start under low moring irradiance.
Maximum power
controllers add to the complexity and cost of a system, in
addition
to creating an approximate five percent power drain on the
array. Indications
are that MPCs are most cost-effective in
systems over about one kilowatt peak capacity.
Below this level,
it may be more cost-effective to substitute extra array
capacity
for an MPC.
Local production of nearly all components except the solar
cells
appears possible in many developing countries.(*) India and
Brazil
have begun cell manufacture and some other countries are
considering
the assembly of modules from imported cells.
Since solar
cell technology is advancing so rapidly, and crucial choices
among the candidate semiconducting materials have yet to be
made,
(*) For an in-depth discussion of the potential for local
production,
see Small-Scale Solar-Powered Pumping Systems:
The Technology
Its Economics and Advancement, by William Halcrow and
Partners, and Intermediate Technology Power, Ltd., and its
supporting
documents concerning manufacture of solar water pumps in
the less developed countries (June 1983).
it may be prudent for most of the Third World to await the
emergence of clearly superior design approaches before
investing
in production facilities.
Other than solar cells, the most
doubtful items for potential local manufacture appear to be
piston pumps, because of their close machining tolerances.
IV. COMPARING THE
ALTERNATIVES
To gain widespread acceptance, small-scale water pumps must
not
only deliver water at a cost below the value of that water;
they
must also do so at a lower cost than alternative methods of
pumping water. Most
prominent among the currently available
alternatives are diesel or kerosene engines, wind power,
animals,
and humans. A good
basis for comparing them with solar is the
cost per unit volume of water delivered under like
conditions
over a like number of years.
This takes into account costs of
purchasing, financing, delivery, installation and start-up,
fuel,
operating and maintenance labor, repairs, and
replacements. In
United Nations Development Programme studies, comparative
costs
of delivered water have been estimated for irrigation,
village
water supply, and livestock watering in Kenya, Bangladesh,
and
Thailand (see bibliography).
Based on 1982 prices, some typical results are shown in
Figures 5, 6, 7, and 8.
31p150.gif (600x600)
There are many qualifications to these results,
too numerous and complex for exposition here.
It must be pointed
out, though, that the solar costs are based on photovoltaic
systems in which the dominant cost item is the solar module
at
its 1982 price of about US$8/ peak watt.
That price is likely to
become much lower within a few years, making the solar
option
more competitive. It
should also be noted that the attractively
low wind power costs are based on average mean wind
velocities
for each country; within those countries there are regions
with
totally inadequate wind.
The costs for animal power are somewhat
optimistic because they do not include the cost of diverting
animals from other activities, and the "low case"
diesel costs
are based on unrealistically optimistic values for fuel cost
and
consumption. With
these points in mind it seems fairly clear
that within a few years solar will be quite competitive in
most
sunny regions that have little wind.
GLOSSARY OF TERMS
Aperature. The solar
collection area.
Dish collector. One
in which the reflecting surface is a paraboloid
of revolution
that concentrates direct solar radiation
onto an
absorber at its focal point. Usually
for
temperatures
above 250 [degrees] C, with two-axis tracking.
Drawdown. The
distance the water level in a well is temporarily
lowered by
pumping.
Flat plate solar collector.
One in which the aperture is essentially
identical to
the area of the absorber surface, the
absorbing
surface is essentially planar, and no concentration
is
employed. Usually for temperatures
below 100 [degrees] C.
Hydraulic output power.
The power imparted by the pump to the
water,
proportional to the product of the flow rate and the
total
pumping head. In watts, roughly equal
to liters per
second times
meters times ten.
Irradiance (radiation intensity).
The energy flux density in the
solar
radiation, usually expressed in watts per square meter.
Static head. The
vertical distance between the water source
level at no
flow and the point of discharge.
Suction lift. The
height that water must be lifted from the
source level
to the pump.
Total pumping head.
The static head plus drawdown and flow pressure
losses in
piping.
Trough collector.
One with a cylindrical parabolic reflecting
surface that
concentrates direct solar radiation onto an
absorber
(usually a tube) at its focal line.
Usually for
temperatures
from 100 [degrees] to 250 [degrees] C, tracking about one axis.
Overall system efficiency.
The fraction of intercepted solar radiation
that
imparts pumping energy to the water, i.e., pump
hydraulic
output power per unit aperture/irradiance.
BIBLIOGRAPHY/SUGGESTED READING LIST
Halcrow, William and Partners, and Intermediate Technology
Power,
Ltd.
Small-Scale Solar-Powered Pumping
Systems: The Technology,
Its Economics
and Advancement (United Nations Development
Programme
Project GLO/80/003). Washington,
D.C.: World
Bank, June
1983. Available through the World Bank,
along
with the
following supporting documents:
1.
Performance tests on improved photovoltaic
pumping systems
2.
Economic evaluation of solar water pumps
3.
Potential for improvement of photovoltaic
pumping systems
4.
Review of solar thermodynamic pumping
systems
5.
Manufacture of solar water pumps in
developing countries
Small-Scale Solar-Powered Irrigation Pumping Systems
(United Nations
Development Programme Project GLO/78/004,
Phase I
report). Washington, D.C.:
World Bank, July 1981.
See also
Small-Scale Solar-Powered Irrigation Pumping System
Technical and
Economic Review (September 1981), amplifying
this report.
Handbook on Solar Water Pumping (United Nations Development
Programme
Project GLO/80/003). Washington, D.C.:
World Bank,
February 1984. This handbook directly
addresses
the concrete
issues and methods of selecting, evaluating,
and specifying a
solar water pumping system.
Kreider, J., and Kreith, F., eds.
Solar Energy Handbook.
New York:
McGraw Hill,
1981. The reader is referred to the
following
chapters:
Chapter 1 for
history of solar thermodynamic water pumping
Chapter 7 for
non-concentrating solar-thermal collectors
Chapter 8 for
intermediate concentration collectors
Chapter 9 for
high concentration collectors
Chapter 22 for
solar powered heat engines
Chapter 24 for
photovoltaics
McNelis, ed.
United Kingdom Section of
International Solar Energy
Society.
Proceedings of Conference on Solar Energy
for Developing
Countries,
Volume on Refrigeration and Water Pumping.
London:
ISES, January 1982.
United Nations Development Programme; World Bank; and
Philippines
Ministry of
Energy. Proceedings of Workshops on
Solar Pumping
in Developing
Countries. Washington, D.C.:
World Bank, June
1981.
PARTIAL
LIST OF SUPPLIERS AND MANUFACTURERS
OF SOLAR WATER PUMPING SYSTEMS
THERMODYNAMIC SYSTEMS (not necessarily mature products):
Dornier
organic Rankine flat plate,
Postfach 1360
approx. 500 watts output
7990 Friedrichshafen 1
FEDERAL REPUBLIC OF GERMANY
Grinakers
fluid overbalancing beam engine,
c/o A. de Beer
flat plate, approx. 200 watts
P.O. Box 349
Rosslyn 0200
REPUBLIC OF SOUTH AFRICA
Grinakers
fluid overbalancing beam engine,
c/o Pelegano Village Industries
flat plate, approx. 200 watts
P.O. Box 464
Gaborone
BOTSWANA
Wrede-Ky
organic Rankine trough
P.O. Box 42
approx. 300 watts output
SF-02701 Kaunianen
FINLAND
PHOTOVOLTAIC SYSTEMS (commercially available and fairly
mature):
AEG--Telefunken Raumfahrttechnik und Neue Technologien
Industriestrasse 29
2000 Wedel, Holstein
FEDERAL REPUBLIC OF GERMANY
Aerimpianti S.p.A.
Via Bergano, 21
20135 Milano
ITALY
ARCO Solar, Inc.
20554 Plummer Street
Chatsworth, California 91311 USA
A.Y. McDonald Corp.
P.O. Box 508
Dubuque, Iowa 52001 USA
Baker-Monitor
133 Enterprise St.
Evansville, Wisconsin 53536 USA
Briau
BP 43
37009 Tours
FRANCE
Grundfos Pump Corp.
2555 Clovis Ave.
Clovis, California 93612 USA
Heliodinamica
Caixa Postal 8085
Sao Paulo 01000
BRAZIL
Intersol Power
11901 West Cedar Avenue
Lakewood, Colorado 80228 USA
Jacuzzi Brothers
11511 New Benton Hwy.
Little Rock, Arkansas 72201 USA
Mobil Solar Energy Corp.
16 Hickory Dr.
Waltham, Massachusetts 02254 USA
Pompes Gitnard Etablissements
179, Boulevard Saint Denis
92402 Courbevoie
FRANCE
Philips GmbH, Unternehmensbereich Licht
und
Anlagen-Energie-Systeme
Monckebergstrasse 7
2000 Hamburg 1
FEDERAL REPUBLIC OF GERMANY
Solar Electric International
31 Queen Anne's Gate
London, SW1H 9BU
ENGLAND
Solar Usage Now Inc.
Box 306
420 East Tiffin St.
Bascom Ohio USA
Solarex Corp.
1335 Piccard Dr.
Rockville, Maryland 20850 USA
Solavolt International
3646 E. Atlanta Ave.
Phoenix, Arizona 85040 USA
Solec International
12533 Chadron Avenue
Hawthorne, California 90250 USA
Tri-Solar Corp.
10 DeAngelo Dr.
Bedford, Massachusetts 10730 USA
Virden Perma-Bilt
2821 Mays Ave.
Amarillo, Texas 79109 USA
Windlight Workshop
P.O. Box 6015
Santa Fe, New Mexico 87502 USA
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