A RESEARCH ON WATER PUMPING THROUGH SOLAR ENERGY

Transcription

1 International Journal of Ecosystems and Ecology Sciences (IJEES) Vol. 7 (1): (2017) A RESEARCH ON WATER PUMPING THROUGH SOLAR ENERGY H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* 1 Department of Agricultural Machinery, Faculty of Agriculture, Cukurova University, Adana, Turkey; 2 Department of Energy Systems Engineering, Faculty of Technology, Kocaeli University, Umuttepe, Kocaeli, Turkey; 3,* Department of Electrical and Energy, Air Conditioning and Refrigeration Technology, Kocaeli Vocational School, Kocaeli University, Mahmutpasa Mah. Mahmutpasa Cad. No: 151, Kullar/Basiskele/Kocaeli, Turkey; *fatmacanka@hotmail.com;hhozturk@cu.edu.tr; hhozturk1@gmail.com; durmuskaya@hotmail.com; Received May, 2016; Accepted September, 2016; UOI license: ABSTRACT Photovoltaic water pumping (PWP) systems are particularly suitable for water supply in remote areas where no electrical energy is available. Due to the high initial costs of the PWP systems, it is necessary to dimension photovoltaic installations as accurately as possible. In this study, some technical properties of a solar water pumping system have been researched and determined in terms of using electrical energy that obtained from solar energy through photovoltaic (PV) principles to assure mechanical energy for the operation of submersible pumps. For this purpose, electrical properties like current, voltage and power and the efficiency of the PV system have been determined. The system was made up of 3 arrays, consisted of 4 modules each, for a total of 12 modules and every module had a total of 12 6 = 72 PV cells. The flow rates of the pumped water, the hydraulic power values of submersible pumps and their efficiencies were calculated using three different submersible pumps, which operated electricity that produced through the PV system. Electrical power, transferred to the accumulator by a module was calculated as W in the PV system. The average electrical power produced by the PV system was calculated as W. Electrical power generation efficiency of the PV system was calculated as 17.86% in average. The average flow rate, hydraulic power and efficiency values of the submersible pumps that have been used for the studies were calculated as in the range of m 3 /h, W and %, respectively. Keywords: Solar water pumping, Photovoltaics, Submersible pump INTRODUCTION The basic method for providing water for the purpose of irrigation is to deliver water from water source to the field and this movement of water requires some amount of energy. The combination of mechanical tools and equipment that are used to deliver water from the water source to the field is called as a pumping plant. Projecting a pumping plant consists of some important engineering issues like selection, installation, operation and maintenance. The main purpose of the irrigation is to provide water for the plant from the water source, when it is needed, with a sufficient amount of water using a minimum amount of energy and operating cost. Recent developments related to energy use 35

2 H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* and energy conservation studies show that irrigation practices have consuming high amount of energy in the agricultural sector. Thus, the studies to reduce energy consumption in irrigation practices are very important to improve irrigation methods, decrease the costs of the processes and increase the efficiencies. Also, the use of new and renewable natural energy sources for irrigation purposes is an alternative to the traditional systems. Moreover, decreasing the consumption of fossil fuels for the purpose of irrigation is an important element to realize targeted clean developments for the sector. In the case of utilization of solar energy, which is one of the most important renewable energy sources for agricultural irrigation helps to reduce the costs of irrigation expenses in the production processes, because the use of conventional energy sources for the irrigation applications is very expensive. Therefore, using renewable energy sources to irrigate agricultural lands has gained great importance to decrease total production costs in agriculture processes and holds great importance to conserve energy and prevent environmental pollution. The development of irrigation processes has a long history and many methods have been used to decrease energy consumption costs. To pump the water for the purpose of irrigation process, different power sources have been utilized in different methods, such as; human power, animal power, wind, solar and fossil fuels etc. Pumping water for the irrigation processes by using solar energy has many advantages over the other irrigation methods such as the method that uses internal combustion engines. In this case, there is no requirement of practical maintenance and the fuel and thus, no polluting effects to the environment. Moreover, it has much longer lifetime. One of the other important advantages of it is benefiting from the sun as an energy source. The main drawbacks of solar irrigation systems are; high initial cost and the efficiency change of the solar irrigation systems depending on the current weather conditions. One of the most promising areas of solar energy applications is the use of the photovoltaic systems as a power source to pump the water for the purpose of irrigation in the countries like Turkey that have too much solar radiation. There are many studies have been implemented to benefit from the solar energy systems and some important improvements have been achieved at different levels. For example, Hamrouni et al. (2009) aimed to examine the influence of the solar radiation variation on the performances of a stand-alone photovoltaic pumping system that consists of photovoltaic generator, dc dc converter, dc ac inverter, an immersed group motor-pump and a storage tank that serves a similar purpose to battery storage. They made a theoretical investigation for controlling and modeling of the system. The obtained simulation results denoted that the decrease of the solar radiation degrades performances of the PV pumping system including the global efficiency and the flow rate. Their analysis was confirmed by simulation and experimental results. Fiasch et al. (2005) investigated the possibility of improving the performance of deep well solar pumping systems by using centrifugal pumps with variable rotational speed and modular number of working stages and the values compared with traditional systems equipped with pumps having a fixed number of stages. In the study, a 30 m 2 PV system with the capacity of approximately 3kW peak power and to a well depth of 100 m were taken into account and regarding a commercial 46-stage submersible pump, it was determined that a breakpoint at the 31st impeller produced an increase close to 9% of the yearly pumped water yield with respect to a conventional, non-modular pump. Ghoneim (2006) studied the results of performance optimization of a photovoltaic powered water pumping system in the climate of Kuwait. The direct coupled photovoltaic water pumping system examined consists of the PV array, DC motor, centrifugal pump, a storage tank that serves a similar purpose to battery storage and a maximum power point tracker to improve the efficiency of the system. The pumped water was aimed to satisfy the domestic needs of 300 persons in a remote area in Kuwait. Assuming a figure of 40 l/person/day for water consumption, a volume of 12 m 3 needs to be pumped daily from a deep well throughout the year. In this context, a computer simulation program was developed to define the performance of the proposed system in the Kuwait climate. The simulation program consisted of a component model for the PV array with maximum power point tracker and component models for both the DC motor and the centrifugal pump. The five-parameter model was adapted to simulate the performance of amorphous silicon solar cell modules. The size of the PV array, PV array orientation and the pump motor hydraulic system characteristics were substituted to achieve the optimum performance for the proposed system. The life cycle cost method was executed to evaluate the economic feasibility of the optimized photovoltaic powered water pumping system. It was explained that the expected reduction in the prices of photovoltaic modules in the near future would make photovoltaic powered water pumping systems more feasible. Kaldellis et al. (2009) attempted to examine the opportunities of a PV powered water pumping system able to meet additional apart from the water pump electricity loads, results in the development of an optimum sizing methodology which was accordingly confirmed by experimental measurements. They determined that a properly 36

3 International Journal of Ecosystems and Ecology Sciences (IJEES) Vol. 7 (1): (2017) designed PV-pumping configuration of 610Wp was capable of covering both the electricity (max 2 kwh/day) and the water (max 400 L/h) management demanded of a large diversity of remote consumers. Qoaider and Steinbrecht (2010) were investigated economic viability of PV technology to supply the whole energy demands to off-grid irrigated-agriculture-based communities in the arid regions in southern Egypt. Electricity generation costs (generated by diesel generators) are typically affected by the high fossil fuel prices, the fuel transport costs and the intensive operation and maintenance necessities. Their study involved the technical design and the calculation of the life cycle costs of a PV system, which was able to supply the village with its whole energy demand. The PV generator was sized to daily pump m 3 of lake water to irrigate 1260 ha acreage plots and to electrify the neighboring village s households. The electricity generation costs and the performance of the designed photovoltaic generator were compared with those of an equivalent diesel generator in order to prove its competitiveness. To calculate the costs of diesel generators-based electricity, the real market value of the diesel fuel of c /L was considered. The results demonstrated that the diesel generators-based electricity unit costs 39 c /kwh, while a unit of PV electricity costs only 13 c /kwh for the equivalent system size and project lifetime. Bakelli et al. (2011) executed one photovoltaic pumping project, which was designed to supply drinking water in remote and scattered small villages situated in Ghardaia (Ghardaia; N, 3 40 E, 450 m) Algeria. They recommended an optimal sizing model to optimize the capacity sizes of different components of photovoltaic water pumping system using water tank storage. The recommended model considered the sub-models of the pumping system and used two optimization criteria, the loss of power supply probability concept for the reliability and the life cycle cost for the economic evaluation. Mokeddem et al. (2011) carried out an experimental study to investigate the performance of a simple, directly coupled dc photovoltaic powered water pumping system. The system comprised of a 1.5 kw PV array, dc motor and a centrifugal pump. The experiment took over a period of 4 months and the system performance was monitored under different climatic conditions and varying solar irradiance with two static head configurations. It has been stated in the study that the motor pump efficiency did not exceed 30%, which is typical for directly-coupled photovoltaic pumping systems, such a system is clearly suitable for low head irrigation in the remote areas, not connected to the national grid and where access to water comes as first priority issue than access to technology. Since the system could operate without batteries and sophisticated control units, initial investment cost was low and maintenance, repair and design costs were also less. In this study, some technical properties of a solar water pumping system have been investigated in terms of using electrical energy that obtained from solar energy through the photovoltaic (PV) principles to assure mechanical energy for the operation of three submersible pumps. In this context, electrical properties like current, voltage and power and the efficiency of the PV system have been determined. The PV system was made up of 3 arrays, consists of 4 modules each, for a total of 12 modules and every module had a total of 12 6 = 72 PV cells. The flow rates of the water that being pumped, the hydraulic power values of submersible pumps and their efficiencies were calculated at the condition of water pumping with three different submersible pumps, which operated by using electricity, produced through the PV system. The primary purpose of this study was to decrease the energy consumption of the water pumping, in other words, reduction of the energy costs in the process of water pumping for the irrigation purposes. The most important feature of the photovoltaic water pumping (PWP) system that considered in this study was being designed as a portable system for the aim of more effective agricultural irrigation. MATERIALS AND METHODS Material The photovoltaic (PV) system Photovoltaic water pumping (PWP) system which was designed by SOMY Energy and Metals Industry, Mersin, generates electricity from solar radiation energy depending on PV principles and had 3 PV arrays. It was placed on a forward dumping agricultural trailer. The electricity that generated by PV system was stored in the accumulators in the system and it was used as a power source in order to run appropriate agricultural equipment. The PV system was made up of 3 arrays, consists of 4 modules each, for a total of 12 modules and every module had a total of 12 6 = 37

4 H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* 72 PV cells (Fig. 1). In the PV systems, which were made of silicon dioxide, 12 6 =72 4= = 864 PV cells were located in total. The electricity that generated by PV cells is collected at one point by connecting two pieces of connection cable that placed at the back of the cells, in series or parallel. Then the electricity is transmitted to the regulator to eliminate the current fluctuations. The current flows through the regulator, and it is transferred to the accumulator to be stored therein. DC current that coming from the accumulator is transmitted to the inverter (converter) to be converted into AC and electrical current is increased from the value of 48 V to 380 V three-phase current. The electric current that is taken from inverter is used for the operation of electrical devices.as it can be seen in Fig. 1, the PV system was placed on a forward dumping agricultural trailer. The agricultural trailer has been equipped with direction indicator lamps and reflectors. At the front of the trailer there is a cabinet which is used for the protection of inverter, regulator and a board. The PV system is made up of 3 arrays, consists of 4 modules each, for a total of 12 modules. PV system has storage batteries on the right and left sides, they can move towards to the middle, beneath the accumulator that placed in the middle of the PV system construction by moving on the slide in order to get in the correct position of the road (Fig. 2). In order to move the PV system to the desired location, the 3 PV arrays were placed on the top of the chassis of the forward dumping agricultural trailer with hydraulic piston. When the PV system is brought to the desired height with a hydraulic system, there is four-stage-adjustable safety support is available, which is located between the subframe and the top chassis and manufactured in two pieces of profiles in the sizes of mm and 2100 mm in length. The two rubber wheels are used to carry the system. The axle was made of two gussets by welding onto the forehead (Fig. 3a) and Fig. 3b)). The photovoltaic (PV) module The PV module consisted of 72 units of cells in total, which was designed and placed into frames in the sizes of mm. The surface of the PV module was covered with tempered glass not to reflect solar radiation. One piece of PV module produces 260W of power, so the amount of power that total 12 of the PV modules produce was 3.12 kw. Some physical and electrical characteristics of PV modules are given in Table 1. Regulator-inverter-battery The function of a regulator is to control the flow of current from a generating source to the battery. In this case, the regulator controls the charge from the PV modules to the battery (Fig. 4a)). Also regulators protect the batteries from overcharge and/or excessive discharge in PV systems. When the batteries are fully charged regulators keep the battery fully charged without damage and they disconnect the PV array. Inverters (Fig. 4b)) receive DC voltage from the PV array transform it into AC voltage in order to be used by electrical consumers, and they raise this AC voltage to the power of 8 kw and 380 V voltage value. Accumulators (Fig. 4c)) store the direct current that coming from the PV array, they assure the continuity of the system operation when there is no sun. In the system there are 16 batteries are available with the capacity of 12 V 200 Ah each. Submersible pumps In this study to investigate the usability of a PV system for the purpose of agricultural irrigation, 3 different featured submersible pumps were used in the diameter of 4 and 6. The submersible pump with a diameter of 4 had floating fan, stainless steel body and plastic parts, rotation speed was 2900 r/min and its direction of rotation was counter-clockwise. The submersible pump with a diameter of 6 was used for two different designs (three-stage and six-stage) in the experiments. The six-stage submersible pump had stainless steel body and plastic parts and its rotation speed was 2900 r/min and direction of rotation was counter-clockwise. The current and voltage measurements in the PV system The voltage and current values of the electricity that produced by the PV system were measured with a digital multimeter. A multimeter is an electronic measuring instrument that measures current (amps), voltage (volts), resistance (ohms) and short-circuit. Multimeters are used in the electrical and electronics industry, and they are manufactured as analog and digital. The measurement can be made by choosing a desired value with the commutator that placed on the multimeter. Nowadays, multimeters are highly developed and many new features have been added to them. Multimeters are used to trouble-shoot electrical problems in a wide range of industrial and household devices for example electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems. In addition to standard parameters like current, voltage and resistance, multimeters can measure 38

5 International Journal of Ecosystems and Ecology Sciences (IJEES) Vol. 7 (1): (2017) some other parameters like frequency, temperature, capacitance. Many manufacturers specify the multimeter's accuracy of measurement is % 2+5. That means total error can be found by adding 2% of measured value and 5 times of the resolution. As it can be understood by the expression of the calculation method, the higher the resolution, the lower the measurement error and more accurate measurement will be made. The climate features of Mersin province Mersin province is located in between north latitude and east longitude. The length of the land border of the province is 608 km and the coastal length is 321 km and total square measure is 15,953 km². A large part of the province of Mersin consists of quite high, hilly terrain and rocky western and central part of Toros Mountains. The city center, Tarsus and Silifke are placed in plains and gently sloping areas as of the mountains extend to the sea. In addition, the other flat or gently sloping areas can be seen in the north or in the higher parts of the mountains. Mersin and its surrounding areas have typical subtropical climate which is mild and warm. The months of the summers are hot and extremely humid, the temperature is around 28 C the average humidity is 88% and as for the winter months, they are warm and rainy, the temperature is around 15 C. The annual average rainfall is 1096 mm. Given the 35-year monthly average temperatures values of Mersin ( ), the average temperature of the province for many years has been around 23 C and that means the province is placed in one of the Turkey s hottest region. On the other hand, in Mersin, the excessive moisture can be overwhelming especially during the summer months. The most rainfall of the city can be seen in the period of December-January. The total solar energy in Mersin is in the range of kwh/m 2 day, the duration of sunshine is in the range of hours. Method The Electrical Power that Produced in PV Systems The amount of electrical power that being produced by the PV system has been calculated according to the system's open circuit current and short circuit voltage values as it can be seen down below: EPV Ioc Vsc (1) Where: E PV= The amount of electrical power that produced by the PV system (W), I oc = Open circuit current value (A) and V SC = Short-circuit voltage value (V). Efficiency of the PV System Electrical power conversion efficiency of the PV systems ( pc) is defined as the ratio of the amount of electricity that generated by the PV system to the amount of solar energy that coming on the surface of the PV and it is calculated as follows: Isc V S A oc PV (2) t Where: A = Surface area of the PV (m 2 ), I sc = Short circuit current value (A), S t = Total solar radiation (W/m 2 ), V oc = Short-circuit voltage value (V) and PV = The efficiency of the PV system (%). The Power Pumping Plant In the facility, if in between the water supply and the peaks that is increased by the water, (Q) the flow rate and specific gravity of the water (γ) (with manometric height ((H m=h g+h k) to be supplied) are known, the energy that given to the water per unit of time by the pump or hydraulic power of the pump (P h), are determined as follows: Q Hm Ph (3)

6 H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* The value that specified by the equation (3) is known as useful power or output power. Various losses occur during the exchange of energy in a pump which is known as a work machine. In other words, a portion of the energy is used to accommodate various losses beside the hydraulic energy. The power that required to be applied to the shaft of the pump is greater than the hydraulic power. The ratio between these two values is named as the efficiency of the pump. Ph p 100 (4) P f Pump efficiency (η p) depends on the structural characteristics of the pump that used in the plant and operating conditions of the plant. If the efficiency of the pump is high that indicates that in response to the received energy, the work is done with the less energy loss. The efficiency of irrigation pumps varies around the value of % depending on vertical height of the water from where it is removed, water velocity and the amount of the pumped water. The power that required to be applied to the shaft of the pump is called as brake power (P f, kw) and it is calculated by using the equation (5). The brake power of the pumping the plant determines the size of the energy source that required for the operation of the plant. P Q H P m h f (5) 102 p p Where: H m = Total manometric head of the pump (m), Q = The flow rate of the irrigation water (m 3 /h), P f = The brake power of the pump (kw), P h = The hydraulic power of the pump (kw), = Specific mass of the irrigation water (kg / L) and p = The efficiency of the irrigation pump (%). RESULTS The electricity values that produced by the PV system Short-circuit current and voltage values that produced by a module of the PV system and electrical power that calculated depending on these values are given in Table 2. To increase the charge capacity of the batteries in the PV system, PV modules were operated with short-circuit current and connected in series. the electricity that produced by a PV module in the PV system, as results of three measurements, the average current and voltage values were determined as 7.81 A and V, respectively. Depending on the average current and voltage values the amount of electrical power that transferred to the accumulator by one module is calculated as W. The three measurements were made at the input and output of the inverter for the determination of the voltage value of the electric current from the batteries to the inverter in the PV system. The results that determined based on these measurements are given in Table 3. While DC voltage was measured as V at the input of the inverter, AC voltage value was measured as V at the output of the inverter in the PV system. Depending on these values, the average electrical power that produced by the PV system was calculated by using equation (1), as W. The Efficiency of the PV System Electrical power generation efficiency of the PV system was determined by using equation (2) and the calculated values are given in Table 4. The average electrical power generation efficiency of the PV system was calculated as 17.86%. Measured Flow Rate Values The flow rate values of the submersibles pump which were run by using the electricity that generated in the PV system are also given in Table 5. The water was drawn from a depth of 6 m in average. The average flow rate of the submersible pump which has 4 of diameter and 11-stage was measured as m 3 /h. While the flow rate of the submersible pump which has 6 of diameter and 3-stage was measured as 28.8 m 3 /h, the flow rate of the submersible pump that had 6-stage was determined as 21.6 m 3 /h, respectively. 40

7 International Journal of Ecosystems and Ecology Sciences (IJEES) Vol. 7 (1): (2017) Hydraulic Power of the Pump Hydraulic power that can be identified as the power that delivered to the water by the pump. Hydraulic power values were calculated by using the equation (3) and the values are given in Table 6. The average hydraulic power of the submersible pump which has 4 of diameter and 11-stage, was calculated as W. While the hydraulic power of the submersible pump which has 6 of diameter and 3-stage was determined as W, the hydraulic power of the submersible pump that had 6-stage was calculated as W. The Efficiency of the Pump The efficiency of the pump can be described as the power that transferred to the water by the pump, in response to the power, consumed by the pump. The efficiency values of the pump were calculated by using the equation (4) and these determined results are given in Table 7. The average efficiency of the submersible pump which has 4 of diameter and 11-stage was calculated as 46%. While the efficiency of the submersible pump which has 6 of diameter and the efficiency of the submersible pump that has 3-stage was determined as 56.6%, the efficiency of the one that had 6-stage was calculated as 42%. Figure 1. Photovoltaic (PV) system. Figure 2. In the view of the PV system path location. a) 41

8 H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* b) Figure 3 a) and b). In the view of the operating mode of the PV system. a) Regulator b) Inverter c) Accumulator Figure 4. a), b) and c) Regulators, inverters and accumulators in the PV system. Table 1. Some physical and electrical characteristics of PV modules. Properties Values Length =1960 Dimensions (mm) Width = 986 Thickness = 50 Mass (kg) 23 P m (W) 260 V oc (V) 43.2 I sc (A) 7.95 V mp (V) 35.4 I mp (A) 7.34 The highest voltage of the system (V) 1000 Power output tolerance % 5 Table 2. The short circuit current, the voltage and the power values that produced in a module of the PV system. Measurements Current Voltage The power that produced in (A) (V) the module (W) Measurement Measurement Measurement Average Table 3. The voltage measurements at the inlet and outlet of the inverter. Measurements The voltage value at the inlet of the inverter (DC) (V) The voltage value at the output of the inverter(ac) (V) The power that produced in the PV System (W) 42

9 International Journal of Ecosystems and Ecology Sciences (IJEES) Vol. 7 (1): (2017) Measurements Measurement Measurement Measurement Average Table 4. Electrical power generation efficiency of the PV system. The power that produced in the PV Systems (W) Total Solar Radiation (W/m 2 ) The Surface Area of the PV System (m 2 ) The Electrical Efficiency of the PV System (%) Measurement Measurement Measurement Average Table 5. The flow rate values of the pump. The flow rate values (m 3 /h) Measurements Pump Diameter ( )/The number of the stage (Quantity)/Power (kw) 4/11/3 6/3/4 6/6/4 Measurement Measurement Measurement Average Table 6. Hydraulic power ratings of the pump. Hydraulic Power (W) Measurements Pump Diameter ( )/The number of the stage (Quantity)/Power (kw) 4/11/3 6/3/4 6/6/4 Measurement Measurement Measurement Average Table 7. Pump efficiency values. The Efficiency of the Pump (%) Measurements Pump Diameter ( )/The number of the stage (Quantity)/ Power (kw) 4/11/3 6/3/4 6/6/4 Measurement Measurement Measurement Average CONCLUSIONS Electrical power that was transferred to the accumulator by a module was calculated as W in the PV system. The average electrical power produced by the PV system was calculated as W. Average electrical power 43

10 H. Huseyin Ozturk 1, Mehmet Akif Koksal 1, Durmus Kaya 2, Fatma Canka Kilic 3,* generation efficiency of the PV system was calculated as 17.86%. The average flow rate of the submersible pump which has 4 of diameter and 11-stage was measured as m 3 /h. While, the flow rate of the submersible pump which has 6 of diameter and 3-stage was measured as 28.8 m 3 /h, the flow rate of the submersible pump that had 6- stage was determined as 21.6 m 3 /h, respectively. The average hydraulic power of the submersible pump which has 4 of diameter and 11-stage was calculated as W. While the hydraulic power of the submersible pump which has 6 of diameter and 3-stage was determined as W, the hydraulic power of the submersible pump that had 6-stage was calculated as W. The average efficiency of the submersible pump which has 4 of diameter and 11-stage was calculated as 46%. While the efficiency of the submersible pump which has 6 of diameter and 3-stage was determined as 56.6%, the efficiency of the submersible pump that had 6-stage was calculated as 42%. Suggestıons Solar cell (PV) systems have high initial investment cost, therefore it is very important that these systems should be dimensioned as accurately as possible. In the design of irrigation systems, which powered by solar energy it is necessary to make pre-calculation or estimation of the total height of the pumped water, daily amount of required water and of the average solar energy in the region. In solar irrigation systems the variation amount of required water throughout the year is to take into consideration. It is very important to give special attention to the water distribution system and the characteristics of the product that needs to be irrigated. The costs of the water distribution system should be low and the water losses should be minimized for the pumping system without creating an additional height. In the design of solar irrigation systems, the region's climate data, the plant characteristics that related to its water consumption, the specifications of the irrigation system and the features that related to the water resource should be taken into consideration. The electric motor that is to be used in the solar irrigation system should be selected depending on the power need and the current type. The following factors must be considered for the energy efficiency and cost-effectiveness of the irrigation system and PV generator:1) The water source should be used effectively. Only the amount of water that needed for the product should be considered. This amount is determined based on the rainwater retention capacity of the soil in the rainfall period.2) In order to equalize the pressure in the irrigation head the amount of water that needed for the product should be provided at the minimum required height on the ground level.3) For a particular product, the most efficient irrigation method should be applied. The most effective method for fruit trees irrigation is subsurface drip irrigation method, which can be applied by soil-embedded emitters by way of dripping water. Acknowledgements. The authors thank Cukurova University, Faculty of Agriculture for assembling much of the data used in this article and the project was supported by the Scientific Research Projects (Project code: ZF2010YL5). REFERENCES Bakelli Y, Arab AH, Azoui B. (2011) Optimal sizing of photovoltaic pumping system with water tank storage using LPSP concept. Solar Energy 2011;85: Fiaschi D, Graniglia R, Manfrida G. (2005) Improving the effectiveness of solar pumping systems by using modular centrifugal pumps with variable rotational speed. Solar Energy 2005;79: Ghoneim AA. (2006) Design optimization of photovoltaic powered water pumping systems. Energy Conversion and Management 2006;47: Hamrouni N, Jraidi M, Cherif A. (2009) Theoretical and experimental analysis of the behaviour of a photovoltaic pumping system. Solar Energy 2009;83: Kaldellis JK, Spyropoulos GC, Kavadias KA, Koronaki IP. (2009) Experimental validation of autonomous PVbased water pumping system optimum sizing. Renewable Energy 2009;34: Mokeddem A, Midoun A, Said Hiadsi DK, Raja IA. (2011) Performance of a directly-coupled PV water pumping system. Energy Conversion and Management 2011;52: Qoaider L, Steinbrecht D. (2010) Photovoltaic systems: A cost competitive option to supply energy to off-grid agricultural communities in arid regions. Applied Energy 2010;87: