Experimental energy analysis of a stand-alone photovoltaic-based water pumping installation

Maturity of the photovoltaic (PV) technology is emphasized by the numerous types of applications encountered nowadays. One of the most interesting applications, however, is the use of PV units for pumping water, i.e. the implementation of PV pumping systems (PVPSs) in order to cover both irrigation and potable water needs, especially in remote areas where connection to the local grid is not always feasible. To further establish the utilization of such systems, the performance of a typical PVPS is currently examined. For this purpose, both the efficiency of the system and the ability to transfer water are determined. Detailed measurements provided by a series of experiments are used, while for increased reliability of the results presented, an error analysis is accordingly carried out. Finally, from the results obtained, one may argue that a similar PVPS not only comprises an environmentally friendly solution but also contributes substantially to the satisfaction of remote communities’ water consumption needs.     

Data acquisition system for photovoltaic water pumps

In Algeria, there are several photovoltaic water pumping system (PVWPS) which are situated in remote areas. Typical problems are detected as sizing of photovoltaic (PV) generator (over-sizing) and maintenance (underestimate) by many operators. Due to the high cost of setting up and maintaining a large number of data acquisition systems for the PVWPS, we have developed a real time expert system based on central microcomputer used as a micro-server, with a low cost. This paper presents a design of a universal data acquisition system for Algeria with available components and easily accessible with a central server. This data acquisition system analyses the performance of PVWPS. The systems hardware and software architectures and an application to test its performance are described.     

ANFIS-based modelling for photovoltaic power supply system: A case study

Due to the various seasonal, monthly and daily changes in meteorological data, it is relatively difficult to find a suitable model for Photovoltaic power supply (PVPS) system. This paper deals with the modelling and simulation of a PVPS system using an Adaptive Neuro-Fuzzy Inference Scheme (ANFIS) and the proposition of a new expert configuration PVPS system. For the modelling of the PVPS system, it is required to find suitable models for its different components (ANFIS PV generator, ANFIS battery and ANFIS regulator) that could give satisfactory results under variable climatic conditions in order to test its performance and reliability. A database of measured climate data (global radiation, temperature and humidity) and electrical data (photovoltaic, battery and regulator voltage and current) of a PVPS system installed in Tahifet (south of Algeria) has been recorded for the period from 1992 to 1997. These data have been used for the modelling and simulation of the PVPS system. The results indicated that the reliability and the accuracy of the simulated system are excellent and the correlation coefficient between measured values and those estimated by the ANFIS gave a good prediction accuracy of 98%. Additionally, test results show that the ANFIS performed better than the Artificial Neural Network (ANN), which has also being tried to model the system. In addition, a new configuration of an expert PVPS system is proposed in this work. The predicted electrical data by the ANFIS model can be used for several applications in PV systems.     

Improving the effectiveness of a photovoltaic water pumping system by spraying water over the front of photovoltaic cells

The photovoltaic cells will exhibit long-term degradation if the temperature exceeds a certain limit. Photovoltaic cells are the heart of photovoltaic water pumping systems. In order to utilize PV power and increase photovoltaic water pumping system efficiency, it is necessary to keep PV cell temperature and cell reflection as low as possible. The purpose of this study is to investigate the possibility of improving the performance of a photovoltaic water pumping system. This is performed by spraying water over the photovoltaic cells. The results are compared with traditional systems. Experimental results show that the cells power is increased due to spraying water over the photovoltaic cells. This can significantly increase the system and subsystem efficiency and the pump flow rate when operating under different heads. Measurements of the short circuit current of the module, which is nearly temperature-independent, indicated that the water spray improved the system optical performance.     

Load independent efficient,transformerless inverter for photovoltaic applications

The overall efficiency of photovoltaic power systems (PVPS) depends on the efficiency of the PV panels, the storage batteries, and the efficiency of the inverter circuitry. The last is greatly influenced by the connected load, as the efficiencies are severly reduced when operating at low loads. This is especially effective when the PVPS is most likely to operate with a fraction of the full load. The suggested inverter has excellent efficiency characteristics over a wide power range, and because it contains only electronic components further cost reduction can be expected. Experimentally this inverter is designed for a 120 W output using thyristor switching devices; the efficiency obtained is 88% at full load and 85.2% at 10% of full load, with a maximum output voltage of 60 V stepped sinewave with frequency of 50 Hz. However, higher power outputs could also be achieved with this type of inverter.     

Performance of solar systems with non-linear behavior calculated by the utilizability method: application to PV solar pumps

Based on the utilizability method we derived, in the first part of the paper, an analytic expression to calculate the time average of physical quantities non-linearly dependent on collected solar radiation. Results are applied to photovoltaic pumping systems (PVPS). Water flow propelled by various types of pumps, centrifugal or progressive cavity displacement, for example, can be conveniently written as a second degree polynomial of the collected solar radiation. In that case, the long-term time average of relevant physical parameters, like water flow or hydraulic power, can be calculated with a very simple expression. The procedure is validated comparing long-term averages of maximum water volume pumped by a PV system, obtained with the utilizability method, with those found by running a 10-year time series. Comparison is made for several climatic regions in Brazil. Results show very good agreement for every month of the year and all locations, with a maximum deviation of 1.7%. The method applied to calculate long-term averages, maximum water volume for example, can be useful for evaluation and design procedures of photovoltaic pumping equipment.     

Techno-economic analysis and modelling of a remote photovoltaic water pumping system in the desert of Tunisia

For estimating the performance of a photovoltaic (PV) water pumping system without battery storage, a simple algorithm has been developed. This simulation program uses the hourly global solar radiation, the hourly ambient temperature and the hourly wind speed as the input, moreover the characteristics of region (latitude, longitude, ground albedo) and characteristics of PV water pumping system (orientation, inclination, nominal PV module efficiency, NOCT, PV array area, PV temperature coefficient, miscellaneous power conditioning losses, miscellaneous PV array losses, temperature of reference, moto-pump efficiency and inverter efficiency). This work allows evaluating the economic interest of a remote PV water pumping systems in the desert of Southern Tunisia, which will have to satisfy an average daily volume of 45 m³ throughout the year compared to another very widespread energy system in the area, the diesel genset (DG), by using the method of the life-cycle cost (LCC). The cost per m³ of water was calculated for this system. It is found that the LCC for PV system is 0.500 TND/m³ and the LCC DG is 0.837 TND/m³. The present study indicates economic viability of PV water pumping systems in the desert of Tunisia.     

Optimal sizing of photovoltaic pumping system with water tank storage using LPSP concept

This paper recommends an optimal sizing model, to optimize the capacity sizes of different components of photovoltaic water pumping system (PWPS) using water tank storage. The recommended model takes into account the submodels of the pumping system and uses two optimization criteria, the loss of power supply probability (LPSP) concept for the reliability and the life cycle cost (LCC) for the economic evaluation.With this presented model, the sizing optimization of photovoltaic pumping system can be achieved technically and economically according to the system reliability requirements. The methodology adopted proposes various procedures based on the water consumption profiles, total head, tank capacity and photovoltaic array peak power. A case study is conducted to analyze one photovoltaic pumping project, which is designed to supply drinking water in remote and scattered small villages situated in Ghardaia, Algeria (32°29′N, 3°40′E, 450 m).     

Systematic procedures for sizing photovoltaic pumping system,using water tank storage

In this work, the performances of the photovoltaic pumping destined to supply drinking water in remote and scattered small villages have been studied. The methodology adopted proposes various procedures based on the water consumption profiles, total head, tank capacity and photovoltaic array peak power. A method of the load losses probability (LLP) has been used to optimize sizing of the photovoltaic pumping systems with a similarity between the storage energy in batteries and water in tanks. The results were carried out using measured meteorological data for four localities in Algeria: Algiers and Oran in the north, Bechar and Tamanrasset in the south. The results show that the performance of the photovoltaic pumping system depends deeply on the pumping total head and the peak power of the photovoltaic array. Also, for the southern localities, the LLP method shows that the size of the photovoltaic array varies versus LLP on a small scale. On the other hand, for the northern localities, the sizing of the photovoltaic array is situated on a large scale power. Because of the current high crud-oil price, the photovoltaic pumping still to be the best adopted energy resource to supply drinking water in remote and scattered villages.     

光伏水泵系统配置优化的实验及仿真研究

该文旨在评估日照条件、系统配置等因素对光伏水泵系统性能和经济性表现的影响程度.采用实验手段,结合对系统数学模型的分析,并利用Matlalb,simulink 工具对系统效率及运行效果进行了仿真研究.最终得出静态扬程、日照强度大小和分布以及光伏阵列容鼍对光伏水泵系统效率和经济性能的影响的结论,并给出了用于优化系统成本的泵型及光伏阵列容量大小的选择依据.     

A procedure to size solar-powered irrigation (photoirrigation) schemes

The high cost of photovoltaic solar power makes it necessary, before undertaking any subsequent study, to dimension photovoltaic installations as accurately as possible. We here present a procedure to estimate the required dimension of a photovoltaic installation designed to power a pumping system for the drip irrigation of an olive tree orchard in SW Spain. The method consists of three main stages: (1) One determines the irrigation requirements of the specific estate according to the characteristics of its soil-type and climate. (2) A hydraulic analysis of the pumping system is made according to the depth of the aquifer and the height needed to stabilize the pressure in the water distribution network. (3) Finally, one determines the peak photovoltaic power required to irrigate a 10 ha sub-plot of the estate taking into account the overall yield of the photovoltaic-pump-irrigation system.We call this arrangement “photoirrigation”, and believe that it may be of great utility to improve the output of such socially significant crops as olives and wine grapes, optimizing the use of water and solar energy resources at the same time as preserving the environment.     

Experience with a surface floating PV pumping system: A case study in Khartoum

In a country like Sudan, where the power grid extension is limited to a small area, and fuel shortages and road inaccessibility cause major problems in providing the basic energy needs to rural areas, small scale PV systems could be a comparable application against diesel driven units. One of the main needs is water pumping for drinking, as well as irrigation purposes, so PV power pumping systems could be one of the solutions to the growing energy demand in rural areas. Such systems should ensure high reliability and low/no maintenance cost, otherwise they cannot compete with conventional systems, even in the long term. Therefore, the investigation of the field behaviour of new products is essential to characterize such designs under prevailing conditions. In this paper, a surface floating PV pumping system's performance and its technical feasibility under Khartoum's climatic conditions are investigated. Technical problems encountered with the operation of this system are clearly defined, and suggestions for design modification are advanced.     

Experimental investigation of solar powered diaphragm and helical pumps

For several years, many types of solar powered water pumping systems were evaluated, and in this paper, diaphragm and helical solar photovoltaic (PV) powered water pumping systems are discussed. Data were collected on diaphragm and helical pumps which were powered by different solar PV arrays at multiple pumping depths to determine the pumping performance, efficiency, and reliability of the different systems. The highest diaphragm pump hydraulic efficiency measured was ∼48%, and the highest helical pump hydraulic efficiency measured was ∼60%. The peak total system efficiency (e.g. solar radiation to pumped water) measured for the diaphragm and helical pumps were ∼5% and ∼7%, respectively (based on PV modules with ∼12% efficiency). The daily water volume of the three-chamber high head diaphragm pump performed better than the dual-chamber high head diaphragm pump (∼5 to ∼100% depending on PV array input power and pumping depth). Use of a controller was shown to improve the quad diaphragm pump performance below a solar irradiance of 600 W/m² (20 m head) to 800 W/m² (30 m head). While diaphragm pumps made mostly of plastic demonstrated similar to much better pumping performance than diaphragm pumps made with a high proportion of metal, the metal pumps demonstrated a longer service life (>2 years) than the plastic pumps service life (<2 years). Helical pumps analyzed in this paper were capable of deeper pumping depths and usually demonstrated a longer service life than the diaphragm pumps that were analyzed.     

面向用户冷、热、电负荷需求的多能源系统耦合运行优化策略

建立了由风能和太阳能作为驱动能源的冷热电联产多能互补系统(DCERs CCHP),包含发电、冷热电联产(CCHP)和辅助供热三个子系统,将该系统与以天然气作为驱动能源的冷热电联产系统(NG CCHP)相对比,建立了能源绩效、环境绩效和经济绩效三个维度评估体系,并以能效最高、成本最小和环境效益最大为目标,构建调度策略优化模型,进行实例仿真。结果表明,与传统的NG CCHP相比,DCERs CCHP具有更好的能源绩效、经济绩效和环境绩效;与其他单目标优化模式相比,综合优化模式下的系统运行效果最佳;NG占比增加将降低项目盈利能力,风电、光伏设备成本降低将提升项目的盈利能力。     

Techno-economic analysis of photovoltaic pumping system for rural water supply in Ethiopia

The diesel-driven water pumping systems have a great impact on rural water supply in Ethiopia in past decades due to the lack of access to grid electricity and associated capital intensive nature of grid expansion to rural areas. However, the requirement of diesel generator for frequent maintenance and soaring fuel cost encourages the government and concerned bodies such as NGO to go for most reliable and cost-effective alternatives. In this paper, direct coupled photovoltaic (PV) pumping system has been designed for hypothetical rural village in southern region near Arba Minch (latitude 6.02^″N, Longitude 37.54^″E) to show techno-economic feasibility of the technology. The result shows that direct coupled PV pumping system is cost-effective in terms of life cycle cost and technologically feasible for rural water supply by virtue of its very low running cost and high reliability of the component and the system as a whole.     

Dynamic modeling and sizing optimization of stand-alone photovoltaic power systems using hybrid energy storage technology

Economic and environmental concerns over fossil fuels encourage the development of photovoltaic (PV) energy systems. Due to the intermittent nature of solar energy, energy storage is needed in a stand-alone PV system for the purpose of ensuring continuous power flow. Three stand-alone photovoltaic power systems using different energy storage technologies are studied in this paper. Key components including PV modules, fuel cells, electrolyzers, compressors, hydrogen tanks and batteries are modeled in a clear way so as to facilitate the evaluation of the power systems. Based on energy storage technology, a method of ascertaining minimal system configuration is designed to perform the sizing optimization and reveal the correlations between the system cost and the system efficiency. The three hybrid power systems, i.e., photovoltaic/battery (PV/Battery) system, photovoltaic/fuel cell (PV/FC) system, and photovoltaic/fuel cell/battery (PV/FC/Battery) system, are optimized, analyzed and compared. The obtained results indicate that maximizing the system efficiency while minimizing system cost is a multi-objective optimization problem. As a trade-off solution to the problem, the proposed PV/FC/Battery hybrid system is found to be the configuration with lower cost, higher efficiency and less PV modules as compared with either single storage system.     

Influence of pumping head, insolation and PV array size on PV water pumping system performance

A transient simulation model, using TRNSYS, for AC photovoltaic (PV) water pumping systems is developed and validated against laboratory and field data. Simulations and analysis were undertaken in this work to: (i) discern the influence of mismatch of pump characteristics and well system characteristics on system performance; (ii) obtain average efficiencies and average performance ratios for system, subsystem and PV array over any period of time and under different operating conditions; (iii) analyze the effect of insolation frequency distribution on system performance and (iv) determining the optimum PV array size considering life cycle cost analyses. Simulation and analyses are illustrated using a real case study and utilizing real field data obtained from a system installed in Jordan.     

Optimisation and techno-economic analysis of autonomous photovoltaic–wind hybrid energy systems in comparison to single photovoltaic and wind systems

A techno-economic analysis for autonomous small scale photovoltaic–wind hybrid energy systems is undertaken for optimisation purposes in the present paper. The answer to the question whether a hybrid photovoltaic–wind or a single photovoltaic or wind system is techno-economically better is also sought. Monthly analysis of 8 year long measured hourly weather data shows that solar and wind resources vary greatly from one month to the next. The monthly combinations of these resources lead to basically three types of months: solar-biased month, wind-biased month and even month. This, in turn, leads to energy systems in which the energy contributions from photovoltaic and wind generators vary greatly. The monthly and yearly system performances simulations for different types of months show that the system performances vary greatly for varying battery storage capacities and different fractions of photovoltaic and wind energy. As well as the system performance, the optimisation process of such hybrid systems should further consist of the system cost. Therefore, the system performance results are combined with system cost data. The total system cost and the unit cost of the produced electricity (for a 20 year system lifetime) are analysed with strict reference to the yearly system performance. It is shown that an optimum combination of the hybrid photovoltaic–wind energy system provides higher system performance than either of the single systems for the same system cost for every battery storage capacity analysed in the present study. It is also shown that the magnitude of the battery storage capacity has important bearings on the system performance of single photovoltaic and wind systems. The single photovoltaic system performs better than a single wind system for 2 day storage capacity, while the single wind system performs better for 1.25 day storage capacity for the same system cost.     

A comparative study of maximum power point tracking methods for a photovoltaic-based water pumping system

In this paper the performance of the proposed fuzzy-based maximum power point tracking (MPPT) is investigated and compared with incremental conductance and constant voltage controller for a photovoltaic (PV) pumping system. A fuzzy logic controller with a mamdani inference engine using only nine rules is designed to track the optimum power point. An induction motor has been used to drive the centrifugal pump. The system performance is analysed for different weather conditions. A detailed comparative study presenting the merits and demerits of each technique is also presented in order to develop a relative relationship. Simulation results obtained indicate better performance of the fuzzy-based MPPT algorithm for the PV pumping system.     

Performance of PV water pumping systems

The aim of this work is to analyse the performance of different photovoltaic water pumping systems. The Typical Meteorological Year (TMY) data from four distinct Algerian climatic sites are used: Algiers, Bechar, Oran and Tamanrasset. The study has been carried out for three different profiles, three tank capacities, two PV modules types, two PV array configurations and several pumping heads, applied to two centrifugal pumps. To predict the photovoltaic pumping system performance, it is necessary to use a simulation program, because it takes into account the different parameters of the system and its geographic location. The determination of the best couple generator configuration-pump for a given installation site and a daily load profile is easily obtained by the simulation program.