Solar Pump

SEMINAR REPORT ON “SOLAR PUMP”

ABSTRACT Solar utilization plays a vital role in much discipline like industry, medicines. The present seminar involves the pump technology likes , submerged multistage centrifugal pump-set ,

submerged pump with surface mounted motor ,

reciprocating the

displacement pump , floating motor pump-set.,etc. solar pump are principally for mainly three application village water supply , live-stock watering , irrigation , and solar PV for outdoor lighting ,and so other. The solar pump have been done manually about its performance , sizing of pump, capacity, & comparison point of view.

NOMENCLATURE ∆ H

Water head

∆ Hwell

Well head

∆ Hdyn

Dynamic head

g

gravity

ρ

Density

V

Volume of water

V′

Water delivery rate

Ehyd

Hydraulic energy

Pel

Electrical power

Psol

Solar power

Phyd

Hydraulic power

Ksc

Scale constant

η pv

PV system efficiency

η sys

Hydraulic efficiency

η tot

Overall efficiency

F

Array mismatch factor

E

Daily subsystem efficiency

INDEX

Chapter:1 Chapter:2

Chapter:3 Chapter:4

Chapter:5 Chapter:6 Chapter 7

Introduction of Solar Photovoltaic Water Pumping 2.1 Solar Pumping Technology 2.2 Other Solar Pumping Method 2.3 Comparison Of Solar Pumping Techniques 2.4 Application Of Solar Photovoltaic Pump 2.5 Alternative Design Energy Demand for Water Pumping 3.1 Basic Hydraulic And Energy Relationship. 4.1 Solar Pump Performance 4.2 Costs 4.3 Procurement 4.3.1 Assensing Requirement 4.3.2 Assensing Water Avaibility 4.4 Sizing Of Solar Pumps 4.5 Economics Summary Future Scopes Refrances

CHAPTER-1 INTRODUCTION OF SOLAR (PHOTOVOLTAIC) WATER PUMPING 1.1 The Photovoltaic Array:The PV has a well known current-voltage (I-V) characteristic. The actual operational point on this characteristics ,whilst dependent on a no of factor including radiation and temperature ,is also governed by the characteristics of the system at the output of the array .The only time that is not the case is when some kind of controller is used to isolate the panel from the rest of the pumping system .The panel may be permanently operated at or round the point on curve where max power can be extracted irrespective of the demand from the load.

2.) The Pump:There are several types of pump currently on the market, including: 2.1) Centrifugal pumps:-where the high speed rotation of an impeller drives water to the outlet around the edge of the pump, sucking water from the inlet located at the center of the impeller .

2.2) Piston Pump:-where the motion of the piston draws water into a chamber and then expects it to the output. 2.3) Screw thread pump:-where capsules of water are driven along the screw , in the axial direction ,from entry to exit.e.g.mono,helical rotor ,progressive-cavity pumps. 3) The Pump Motor :As well as there being several types of pump available ,there are also several types of motor including AC and DC.brushed and brushless,permanent magnet and variable reluctance .syncronous and asyncronus, and so on.again each of them has different characteristics .linking the current and voltage input to the torque and rotational output. Under certain condition the I-V requirements of a DC permenanent magnet motor coupled to a centrifugal pump can closely match to the MPP,allowing direct connection from the PV array to the pump motor and on to the pump.Even for centrifugal pumps,how ever, this is not usually the case and the I-V characteristic for positive displacement pumps is generally much worse for direct connection. 4) The Controller:Direct connection between the PV array and the motor will only be possible if the motor requires DC current. if an AC motor is to be used ,or if lower than optimal power output is not desirable ,then electronics systems become necessary ,such as an inverter or a maximum power point tracker, increasing system complexity and losses .Such electronic systems.,while complicated ,are no more complicated than those that run in houses and offices through out the developed world .unfortunately ,they have an uneavaible problem with reliability-one that clearly should not exist and that will be investigated .such a controller , will however effectively isolate the PV array from the pump motor with the optimum voltage /current for the site conditions. 6) The Controller:Direct connection between the PV array and the motor will only be possible if the motor requires DC current. if an AC motor is to be used ,or if lower than optimal power output is not desirable ,then electronics systems become necessary ,such as an inverter or a maximum power point tracker, increasing system complexity and losses .Such electronic systems.,while complicated ,are no more complicated than those that run in houses and offices through out the developed world .unfortunately ,they have an uneavaible problem with reliability-one that clearly should not exist and that will be investigated .such a controller , will however effectively isolate the PV array from the pump motor with the optimum voltage /current for the site conditions.

CHAPTER: 2 THE TECHNOLOGY: Systems are broadly configured into 5 types as described below: 2.1) Submerged multistage centrifugal motor pumpset – Figure 1 This type is probably the most common type of solar pump used for village water supply.The advantages of this configuration are that it is easy to install, often with lay-flat flexible pipework and the motor umpset is submerged away from potential damage.Either ac or dc motors can be incorporated into the pumpset although an inverter would be needed for ac systems. If a brushed dc motor is usedthen the equipment will need to be pulled up from the well (approximately every 2 years) to replace brushes. If brushlessdc motors are incorporated then electronic commutation will be required. The most commonly employed system consists of an ac pump and inverter with a photovoltaic array of less than 1500Wp.

Figure 1 2.2)

Submerged pump with surface mounted motor – Figure 2

This configuration was widely installed with turbine pumps in the Sahelian West Africa during the 1970. It gives easy access to the motor for brush changing and other maintenance.The low efficiency from power losses in the shaft bearings and the high cost of installation has been disadvantages. In general this configuration is largely being replaced by the submersible motor and pumpset.

FIG 2

2.3)

Reciprocating positive displacement pump - Figure 3

The reciprocating positive displacement pump (often known as the jack or nodding donkey) is very suitable for high head, low flow applications. The output is proportional to the speed of the pump. At high heads the frictional forces are low compared to the hydrostatic forces often making positive displacement pumps more efficient than centrifugal pumps for this situation. Reciprocating positive placement pumps create a cyclic load on the motor which, for efficient operation, needs to be balanced. Hence, the above ground components of the solar pump are often heavy and robust, and power controllers for impedance matching often used.

FIG 3

2.4)

Floating motor pump sets - Figure 4

The versatility of the floating unit set, makes it ideal for irrigation pumping for canals and open wells. The pumpset is easily portable and there is a negligible chance of the pump running dry.Most of these types use a single stage submersed centrifugal pump. The most common type utilizes a brushless (electronically commutated) dc motor. Often the solar array support incorporates a handleor 'wheel barrow' type trolley to enable transportation.

FIG 4 2.5)

Surface suction pump sets- Figure 5

This type of pumpset is not recommended except where an operator will always be in attendance. Although the use of primary chambers and non-return valves can prevent loss of prime, in practice self-start and priming problems are experienced. It is impractical to have suction heads of more than 8 meters.

FIG 5

2.6)

Other Solar Pumping Method:-

Considerations of using locally manufactured equipment for solar water pumping need not necessarily be based on photovoltaic conversion. Functional drawings of some proposed concepts are presented in Figures 6. Many of these pumping arrangements were designed to be manufactured using rather simple processes and tools. The feasibility of even production overseas in part could be demonstrated. The behaviour of solar thermal pumps is not very different from that of PV pumps, if tested with reference to varying irradiance levels (refer to the pumping principles depicted in Figures 6) Field experience gathered recently shows that -- even with- out optimizations in detail -- the overall energy performance of such solar thermal pumps is comparable to that of PV pumping systems, even if generally slightly lower. Good efficiency figures recorded with PV pumps have not yet been attainable with the thermal systems. Part of the reason may be the fact that the rating of the thermo-mechanical engines was rather low (more powerful equipment possibly would be more efficient, probably also more cost-effective), but it should not be forgotten that Carnot laws limit the efficiency of solar thermal assemblies, if peak temperatures are limited to rather low levels due to the need to avoid special materials suitable for high-temperature applications and to keep thermal stresses low. None of the solar thermal pumps mentioned has been produced in large numbers so far, conclusions require additional and long-term experience with such systems.

Figure 6. Functional schematic of a solar thermal pumping system according to an organic Rankine cycle (ORC).

Figure:-7 Solar Pumping With Stirling engines (Collector Low Temperature Heat)

2.7)

Comparision Of Pumping Techniques:-

Water pumping has a long history , so many methods have been developed to pump water with a minimum of effort. These have utilized a variety of power sources, namely human energy, animal power, hydro power, wind, solar and fossil fuels for small generators. The relative merits of these are laid out in Table 1 below.

Advantages

Disadvantages

Hand pumps

local manufacture is possible easy to maintain low capital cost no fuel costs

loss of human productivity often an inefficient use of boreholes only low flow rates are achievable

Animal driven pumps

more powerful than humans. lower wages than human power. dung may be used for cooking fuel.

animals require feeding all year round often diverted to other activities at crucial irrigation periods

Hydraulic pumps unattended operation (e.g. rams) easy to maintain low cost long life  high reliability Wind pumps unattended operation easy maintenance long life suited to local manufacture  no fuel requirements Solar PV unattended operation low maintenance easy installation long life

require specific site conditions low output

Diesel and gasoline pumps

fuel supplies erratic and expensive high maintenance costs short life expectancy noise and fume pollution

quick and easy to install low capital costs widely used can be portable

water storage is required for low wind periods high system design and project need  not easy to install high capital costs water storage is required for cloudy periods repairs often require skilled technicians

(TABLE-1 Comparision Of Pumping Techniques)

2.8)

APPLICATIONS: Solar pumps are used principally for three applications: 1. village water supply 2. livestock watering 3. irrigation

2.8.1) A solar pump for village water supply is shown schematically in Figure 1.With village water supply, a constant water demand throughout the year occurs, although there is need to store water for periods of low insolation (low solar radiation). Typically in Sahelian Africa the storage would be 3-5 days of water demand. In environments where rainy seasons occur, rainwater harvesting can offset the reduced output of the solar pump during this period. The majority of the 6000 or more solar pumping systems installed to date are for village water supply or livestock watering

2.8.2) A solar irrigation system (Figure 8) needs to take account of the fact that demand for Irrigation water will vary throughout the year. Peak demand during the irrigation seasons is often more than twice the average demand. This means that solar pumps for irrigation are under-utilised for most of the year. Attention should be paid to the system of water distribution and application to the crops . The system should minimise water losses, without imposing significant additional head on the pumping system and be of low cost.

The suitability of major irrigation systems for use with solar pumps is shown in (Table 2.) Distribution method

Typical application efficiency

Typical head

Suitability for use With solar pumps

Open Channels

50-60%

0.5-1m

Yes

Sprinkler

70%

10-20m

No

Trickle/drip

85%

1-2m

Yes

Flood

40-50%

0.5m

No

Considering the main field of application(represented by pumping systems of small to moderate size) and the aim, to promote solutions for remote locations, the competition to solar pumps comes from water pumping by means of diesel or other internal combustion engines. Grid connection can be ruled out for such applications because of the mostly large distances, and manual pumps -- even if in some cases viable -- will not be considered because of their limitation to a very specific (and definitely lower-scale) application range.

2.8.3) Solar PV for outdoor Lighting: Solar street lighting systems basically consist of a PV panel, inverter and storage battery connected to a light source. It can replace conventional outdoor lighting system and operate for more than 8 hours a day. These systems have been installed in many industrial complexes. The cost of solar street light would vary from Rs. 18,000 to Rs. 21,000 per system.These systems can be fitted with automatic sensors, which would on/off the solar street lighting depending on the light intensity. India is potentially one of the largest markets for solar energy in the world. The estimated potential of power generation through solar photovoltaic system is about 20 MW / Sq.km in India. It is useful for providing grid quality, reliable power in rural areas where the line voltage is low and insufficient to cater to connected load. The Govt. of India is planning to electrify 18,000 villages by year 2012 through renewable energy systems especially by solar PV systems. This offers tremendous growth potential for Indian solar PV industry. Potential availability - 20 MW/Sq.km Installed capacity - 110 MW 2.9)

Alternate Design:There are two ways of using solar power to pump-water:

2.9.1) Directly connecting the solar panel to the pump :or 2.9.2) charging a battery with solar panel and then using the battery to run the pump. Both these system have drawbacks:2.9.3) If the pump is directly power to the solar panel then water can only the pumped when the sun is shining. 2.9.4) Charging the battery first and then using that to run. The pump is less efficient, plus two batteries would be needed so that one could be charging while the another runs the pump making the system move expensive.

CHAPTER:-3 ENERGY DEMAND FOR WATER PUMPING 3.1

BASIC HYDRAULIC AND ENERGY RELATIONSHIPS

The hydraulic energy needed to lift a certain amount of water from a lower water level to a higher level is defined by the product of mass, level difference (∆ H = water head), and acceleration due to gravity g. Using the common units (kilograms, metres, and seconds) the unit of energy is joules. In most technical applications the volume V of water moved is the decisive parameter. Then, the mass of water is represented by the volume multiplied by the den- sity ρ [KSB, 1980]. (Notice that when measuring the voume in m3 a factor

of 103 is introduced as density, leadingto a figure for energy in kJ.) In this calculation site-specific water head requirements play a decisive role, but design features and component characteristics have also to be accounted for. Figure 2 pre- sents a typical configuration of a pumping concept, speci- fying the different water levels and the corresponding water head: ∆ H = (∆ Hwell + ∆ hdyn) + (∆ Hadd + ∆ hloss ) [m]--------------------------------------- (1) The actual water head is always higher than the geodetic level difference. The elements (∆ Hwell + ∆ Hadd) de- fining the ‘‘net’’ water head represent quasistatic (fixed) values. Dynamic effects are caused by the draw-down rate of the water level within the well ∆ hdyn and by hydraulic losses ∆ hloss . Both values are variables depending on the flow regime, the former following a quasi-linear depend- ence, the latter increasing with the square of the flow rate, reprresenting any losses within the piping network. With the water head data (∆ H) and the demand figures for the water volume (V) the hydraulic energy EHYD can be calculated. The deduction leads to a very simple ex- pression, if the constant factors are consolidated into one term. kSC and KSC represent scale constants, the former expressing the conversion from joules into kWh, the latter comprising the physical parameters (gravity and density). If an error of 1% is accepted, water density need only be corrected for if water temperatures exceed 35ºC. EHYD = kSC × g × ρ × V × ∆ H [kWh, V in m3] ----------------------(2a) kSC = 1/3600 [converting kJ to kWh] EHYD = KSC × V × ∆ H [kWh] --------------------------- (2b) KSC = 1/367 [introducing also g and ρ as constants]

Technical performance of pumping systems is usually defined by the water delivery rate, replacing the quantity of water V by a volume flow rate V′ (measured in m3/h [VEB Pumpen, 1987] ). This leads to the net hydraulic power PHYD, which is equivalent to the energy needed to raise the mass of water to the defined elevated level in a certain time interval. PHYD = KSC × V′ × ∆ H [kW] (3)

-----------------------------

Hydraulic and friction losses, inertia effects, and im- perfect performance affect the power demand. Conse- quently the electrical power PEL needed to operate a pump is definitely higher than the hydraulic power. Moreover,in solar applications the energy PSOL captured by means of a PV array must be adequate to provide sufficient elec- tric power and to cover any losses occurring during the conversion process. PSOL >> PEL > PHYD [kW]

---------------------------- (4)

According to this relationship it is obvious that the losses within the system necessitate oversizing of the so- lar conversion components. Thus, the various power lev- els defined in the previous equation are linked by component efficiencies. It is practical to use the following expressions, each describing the energy (power) output compared with the input of any element envisaged: η PV = PEL /PSOL [PV system efficiency] ----------------------(5a) η SYS = PHYD /PEL [electro-mechanic (hydraulic) efficiency] ------(5b) η TOT = η PV × η SYS[overall efficiency of the PV pumping set] ----(5c) Typical data for the mechanical system components have been compiled in Table 3. The classification into different pumping applications pumping technologies illustrates the wide utilisation range of PV pumping and the types of equipment deployed. In contrast to standard electric pumps, which nearly al- ways operate at their nominal speed (and on a rather fixed performance curve), the power fed to PV pumping equip- ment is not constant, affected by the fluctuations of the (solar) irradiance during the day and over the seasons. These varying operating conditions need to be accounted for when an assessment of output figures is made. Efficiencies normally describe steady-state conditions. So it is advantageous for practical reasons to consider nominal operating conditions (where best energy utilisation figures apply, referred to as ‘‘rated conditions’’ in the following) as the basis of layout for solar pumping assemblies also. Accordingly, the data in the table were derived for stable operating modes at determined load (design conditions for water head and

volume flow rate, nominal power and speed of the electric motor).

As in many other technical appliances economies of scale affect system performance: usually larger systems perform better than smaller ones. This applies especially to the mechanical components, whereas the PV conver- sion is notaffected so much by the system size.For con- temporary technologies PV (module) efficiencies usually reach values of 0.1 < η PV < 0.15. According to results of measurements, amorphous cells have operated much less efficiently, so far, but some improvement can be expected in the near term. The distinction between the different efficiencies in the equations 5a to 5c makes it easy to introduce modified figures to perform an assessment based on other technologies. Summarising the results, efficiency figures of very good pumping systems according to the state of the art may reach η SYS < 0.7. Pumping systems available off the shelf (common pump/motor assemblies, based on cen- trifugal pump types) perform at 0.35 < η SYS < 0.65. The total performance efficiency of pumping systems can then be assessed to range within 0.03 < η TOT < 0.1.

.

Figure 9 : Component of PV Pumping system

Application

Typical size Pumpingconcept ( Electric motor CentrifugalDisplacOther power, W) ement

Low head pumping 250 ... > 1200

Efficiency η SYS Average

Best

+

*

--

> 0.35

> 0.55 up to 0.7

Drinking water supply (A)

< 150 ... > 800

*

+

*

0.3 ... 0.4

Drinking water supply (B)

700 ... 5000

+

*

*

> 0.35

High water head pumping

450 ... > 2000

*

*

+

< 0.45

> 0.6 < 0.7

Table 3 : Performance data of pump types and components. Notes:D rink in g w a ter su ppyl (A ): small or moderately sized system with D.C.motor D rin king w ater su ppyl (B ): la rge (sub m e rg ed ) system,sty p ic all y w ith AC m o to rs In PV p u m p ing v ario us tech n o logsiea re used (for de ta ils re fer to the fo llow in g sectio n s) , w ith d ifferen t cap ab ilitie s w ith resp ect to the sp ecific app lica tio n pa ra m ete.rsT he re fo re , the in d ic atiosn rep resen t: + co m m no tech n olog y

* app licabe l(c ertani ty p es)

- not usu al in the sp ec ific case

(Top) F igures 6a and 6b. Characteristic s (water h ead vs. flow rate at constant speeds) of a centrifugal pump. (Left) Figure 6a, pumping head vs flowrate; (right) Figure 6b, required head for deep vs. shallow wells. (Bottom) Figures 6c and 6d. (Left) Figure 6c, specific power requirem ent s for shallow and deep well pumping; (right) Figure 6d, correspondin g start-up condition s (start of operating hours).

N o tes O p eratin g co nd ition s of a p u m p ing system are d efin de by the irrad iate d po w er and the energy ne ed de to p ro vide the p ressure h ead re qu ire.dT h is leads to b eh av iorud ep end etno n the sy stem con d itio n s.

CHAPTER: 4 4.1 PERFORMANCE The performance of some commercially available products is shown in Figure 8. It can be seen that solar pumps are available to pump from anywhere in the range of up to 200m head and with outputs of up to 250m³/day.

Figure 10 Solar pumping technology continues to improve . In the early 1980s the typical solar energy to hydraulic (pumped water) energy efficiency was around 2%

with the photovoltaic array being6-8% efficient and the motor pumpset typically 25% efficient . Today, an efficient solar pump has an average daily solar energy to hydraulic efficiency of more than 4% . Photovoltaicmodules of the monocrystalline type now have efficiencies in excess of 12% and more efficient motor and pumpsets are available. A good sub-system (that is the motor, pump and any power conditioning) should have an average daily energy throughput efficiency of 30-40%.

4.2 COST: A photovoltaic pumping system to pump 25m³/day through 20m head requires a solar array of approximately 800Wp in the Sahelian regions. Such a pump would cost approximately $6,000 FOB. Other example costs are shown in (Table 3)A range of prices is to be expected, since the total system comprises the cost of modules, pump, motor, pipework, wiring, control system, array support structure and packaging. Systems with larger array sizes generally have a lower cost/Wp. The cost of the motor pumpset varies according to application and duties; a low lift suction pump may cost less than $800 whereas a submersible borehole pumpset costs $1500 or more. Output (m³.day) Head (m) 5kWhm/cu.m/ day insolation

Solar Array (Wp)

System Price US$ FOB

Submerged borehole motor pump

40 25

20 20

1200 800

7000-8000 6000-7000

Surface motor/ submerged pump

60

7

840

5000-6000

1200

5000-6000 7500-9000

60

7

Reciprocating positive displacement pump

6 6

840 100

100

1200

Floating motor/ pump set

100 10

3 3

530 85

7500-9000 4000 2000

Surface suction pump

40

4

350

3000

Table 4 - Photovoltaic pumping system specifications

4.3 PROCUREMENT: 4.3.1 Assessing requirements

The output of a solar pumping system is very dependent on good system design derived from accurate site and demand data. It is therefore essential that accurate assumptions are made regarding water demand/pattern of use and water availability including well yield and expected drawdown. Domestic water use per capita tends to vary greatly depending on availability. The long-termaim is to provide people with water in sufficient quantities to meet all requirements for drinking, washing and sanitation. Present short-term goals aim for a per capita provision of 40 litres per day, thus a village of 500 people has a requirement of 20 cubic metres per day . Most villages have a need for combined domestic and livestock watering. Irrigation requirements depend upon crop water requirements, effective groundwater contributions and efficiency of the distribution and field application system. Irrigation requirements can be determined by consultation with local experts and agronomists 4.3.2

Assessing water availability

Several water source parameters need to be taken into account and where possible measured. These are the depth of the water source below ground level, the height of the storage tank or water outlet point above ground level and seasonal variations in water level. The drawdown or drop in water level after pumping has commenced also needs to be considered for well and borehole supplies. This will depend on the ratio between pumping rate and the rate of refill of the water source. The pattern of water use should also be considered in relation to system design and storage requirements. Water supply systems should include sufficient covered water storage to provide for daily water requirements and short periods of cloudy weather. Generally, two to five days water demand is stored. 4.4 Sizing solar pumps:The hydraulic energy required (kWh/day) =

volume required (m³/day) x head (m) x water density x gravity / (3.6 x 106)

=

0.002725 x volume (m³/day) x head (m)

The solar array power required (kWp)

= Hydraulic energy required (kWh/day) Av. daily solar irradiation (kWh/m²/day x F x E)

Where F = array mismatch factor = 0.85 on average E = daily subsystem efficiency = 0.25 - 0.40 typically

4.5 Economics:In general photovoltaic pumps are economic compared to diesel pumps up to approximately 3kWp for village water supply and to around 1kWp for irrigation.

CHAPTER: 5 SUMMARY: In practically all countries in the ‘‘solar’’ region of the globe PV pumps have been installed and operated successfully. The technology to utilize solar radiation as one of the sources of renewable energy for water pumping is available, and a satisfactory degree of maturity and reliability has been demonstrated. So, as far as technical characteristics are concerned, the performance and viability of such systems can be proven. Ongoing efforts aiming at technical progress and improvement of the technology seem promising; further endeavors can still be beneficial. Even if systems in the range between a few hundred watts and some kilowatts are in use, there is still an issue of economic viability as soon as the overall rating exceeds the range of about 1-2 kW. This is the main reason why only slow progress in mar- ket development and towards more widespread dissimilar- nation has been made. PV module cost reductions might improve the situation, but it is uncertain whether this alone can trigger a breakthrough. Solar pumping concepts are advantageous especially with respect to environmental impact, absence of need for constant surveillance, and close to zero operation expen- ditures. Hence, they are not only attractive from an engi- neering point of view. With more political support (which seems adequate in view of the arguments cited above), the technology could become an important economic fac- tor for those countries that are developing their energy infrastructures to ameliorate living conditions of the rural population. Financing schemes for private users and com-munities have been proposed; initial experience with such instruments has been very encouraging.

CHAPTER 6 FUTURE SCOPE The future of PVwater pumping is dependent on a number of factors, both technological and sociological, and both of these must be considered by all involved parties if PVPs are even to being to fulfill their potential. It is evident that a re-think of the technology is required if sustainability is going to be a real operation .The complex electronics systems in use today can never fall within the VLOM category are unlikely to be cheap enough for replacement and are not sufficiently reliable to match the lifetime of the pumping equipment. The options here are therefore: • • •

a significant improvement in designs; a complete re-design of the control systems to become either maintainable (which are highly unlikely)or extremely cheap and easily replace todo away with a control systems completely and employ direction connection between PVarray and pump motor.

CHAPTER 7 REFERENCES: 1)

T.D.SHORT,and R.Oldach,”Solar Powered Water Pumps: The Past ,The Presentand the future.”

2).

World Health Organization and united nation Children Fund, 2000, Global Water Supply and Sanitation Assessment 2000 Report,ISBN92 4 156202 1.

3).

Hahn, a.a995, Technical Maturity and Reliability Of Photo Voltaic Pumping Systems,Proc. Of 13th European PVSolar Conf.,Nice.

4).

Solar Photovoltaic Potential & Prospects-“Godrej GBC Publication Res-fact sheet no-3, June-2004.

5).

Hanel.A.,and Hoang –Gia,l. ,1998 Monitoring Of Representative PVPumping Systems Of the Regional Solar Programm:Result and Conclusion , Proc. Of int.Workshop on PVWater Supply Issue ,November16-18, 1998,pp-85-90.