An-Najah Blogs :: http://blogs.najah.edu/author/emp_3029 An-Najah Blogs :: en-us Sat, 25 Nov 2017 09:53:18 IST Sat, 25 Nov 2017 09:53:18 IST webmaster@najah.edu webmaster@najah.edu On the storage batteries used in solar electric power systems and development of an algorithm for determining their ampere-hour capacityhttp://blogs.najah.edu/staff/emp_3029/article/On-the-storage-batteries-used-in-solar-electric-power-systems-and-development-of-an-algorithm-for-determining-their-ampere-hour-capacityPublished ArticlesCopyright 2004 Elsevier BV All rights reserved On the storage batteries used in solar electric power systems and development of an algorithm for determining their amperehour capacity Marwan M Mahmoud Energy Research Centre An Najah National University Nablus PO Box 721 WestBank Palestine Israel Received 7 October 2003; Revised 18 December 2003; accepted 20 December 2003 Available online 9 April 2004 Abstract Storage batteries are indispensable in all stand alone solar electric systems PV power systems Their efficiencies and life times affect significantly the overall PV system performance and economics Batteries specified especially for use in PV systems have to be distinguished with standing of very deep discharge rate and high cycling stability Ordinary batteries being marketed world wide for use in automobile are mostly not appropriate for PV power systems The most important characteristics of leadacid batteries are presented and discussed in this paper Moreover the paper illustrates an experimental procedure for developing an algorithm for determining the amperehour capacity of batteries operating in PV systems This algorithm enables determining the state-of-charge of a battery by measuring voltage and electrolyte-specific gravity at definite temperature and is applicable also for large battery storage systems Author Keywords: Electrical energy storage; Photovoltaic power systems; Storage batteries Techno-economic feasibility of energy supply of remote villages in Palestine by PV-systems,diesel generators and electric gridhttp://blogs.najah.edu/staff/emp_3029/article/Techno-economic-feasibility-of-energy-supply-of-remote-villages-in-Palestine-by-PV-systemsdiesel-generators-and-electric-gridPublished ArticlesCopyright 2005 Elsevier Ltd All rights reserved Techno-economic feasibility of energy supply of remote villages in Palestine by PV-systems diesel generators and electric grid This article is not included in your organizations subscription However you may be able to access this article under your organizations agreement with Elsevier Marwan M Mahmoud and Imad H Ibrik Energy Research Centre An-Najah National University Nablus PO Box 721 West Bank Palestine Received 14 September 2004; accepted 15 September 2004 Available online 11 November 2004 Abstract As a contribution to the development program of rural areas in Palestine this paper presents three energy supply alternatives for a remote village represented in PV system diesel generator and electric grid Design of these systems and the associated costs of their utilization are illustrated A computer-aided dynamic economic evaluation method with five indicators is used to compare the economic-effectiveness of these energy systems The results show that utilizing of PV systems for rural electrification in Palestine is economically more feasible than using diesel generators or extension of the high voltage electric grid The obtained results represents also a helpful reference for energy planers in Palestine and justify the consideration of PV systems more seriously Keywords: Techno-economic feasibility of energy systems; Rural electrification dynamic evaluation methods; PV-power generators Transient analysis of a PV power generator charging a capacitor for measurment of the I-V characteristicshttp://blogs.najah.edu/staff/emp_3029/article/Transient-analysis-of-a-PV-power-generator-charging-a-capacitor-for-measurment-of-the-I-V-characteristicsPublished ArticlesCopyright 2005 Elsevier Ltd All rights reserved Technical note Transient analysis of a PV power generator charging a capacitor for measurement of the IV characteristics Marwan M Mahmoud a aEnergy Research Centre An Najah National University PO Box 721 Nablus West Bank Palestine Received 31 January 2005; accepted 19 September 2005 Available online 28 October 2005 Abstract Measuring the IV characteristics is of high importance since it can be considered as a quality and performance certificate for each PV generator The most precise and inexpensive measuring method is represented in capacitor charging by the PV generator Using the equivalent circuit of the PV generator with a capacitor as load and applying transient analysis on the circuit we obtain the capacitor charging voltage and current as a function of time as well as their differentials as a function of short circuit current and capacitor size The derived equations facilitate the calculation of proper capacitance size for measuring the IV characteristics and considers the acquisition speed of the measuring system as demonstrated through two measurement samples in this paper The capacitor size is directly and indirectly proportional to the short circuit current and open circuit voltage of the PV generator respectively Accordingly the paper presents a capacitance calculation chart which enables selecting the correct capacitance for measuring the IV characteristics by a computerized data acquisition system Keywords: Photovoltaic generators; IV characteristics measurements; Capacitor charge technique; Transient analysis Solar powered induction motor-driven water pump operating on a desert well, simulation and field testshttp://blogs.najah.edu/staff/emp_3029/article/Solar-powered-induction-motor-driven-water-pump-operating-on-a-desert-wellsimulation-and-field-testPublished ArticlesA photovoltaic-powered water pumping system employing an induction motor pump capable of supplying a daily average of 50m3 at 37-m head has been developed The system was installed on a desert well in Jordan where: the average solar radiation amount to 55kWhm3day to provide the Bedouins living in the well area with drinking water A mathematical model to enable testing the system performance by computer simulation was developed This model allows the representation of motor torque in function of speed and slip at different supply frequencies as well as the flow rate and efficiency of the system in function of supply frequency and pumping head Prior to its installation on the desert well the system performance in accordance with frequency and head was thoroughly tested in the laboratory As illustrated in this paper simulation and laboratory testing results are well matched At constant pumping head the flow rate is proportional to the supply frequency of the motor At constant flow rate the pumping head is proportional to the supply frequency squared only in the range below the peak efficiency of the pump For higher flow rate values a special algorithm based on the experimental results could be developed Higher system efficiency is achievable at higher frequency It is advisable to operate the motor pump at the nominal frequency flow rate and head corresponding to maximum efficiency Long-term field testing of the system shows that it is reliable and has an overall efficiency exceeding 3 which is comparable to the highest efficiencies reported elsewhere for solar powered pumps Renewable Energy Volume 30 Issue 5 April 2005 Pages 701-714 Energy efficiency improvement procedures and audit results of electrical, thermal and solar applications in Palestinehttp://blogs.najah.edu/staff/emp_3029/article/Energy-efficiency-improvement-procedures-and-audit-results-of-electrical-thermal-and-solar-applications-in-PalestinePublished ArticlesEnergy conservation in utilities has played a vital role in improving energy efficiency in the industrial commercial and residential sectors The electrical energy consumption in Palestine has increased sharply in the past few years and achieved by the end of 2001 to 10 per year It is expected that this percentage will increase to about 12 if the current political situation will end hopefully with peace Modern energy efficient technologies are needed for the national energy policy Such technologies are investigated in this paper Implementing of a national 3 years project aiming at energy efficiency improvement in residential and industrial sectors as well as in public utilities which include wide range of diversified audits and power measurements had led to creating this paper Measurement and audit results had shown that the total conservation potential in these sectors is around 15 of the total energy consumption The associated costs of the investment in this field are relatively low and correspond to a pay back period varying in the range from 6 to 36 months Consequently the energy conservation policy will be seriously improved in the forthcoming years It is estimated that 10 of the new energy purchasing capacity will be reduced accordingly Energy Policy Volume 33 Issue 5 March 2005 Pages 651-658 http:dxdoiorg101016jenpol200309008 Field experience on solar electric power systems and their potential in Palestinehttp://blogs.najah.edu/staff/emp_3029/article/Field-experience-on-solar-electric-power-systems-and-their-potential-in-Palestine-1Published Articles Palestine has a large number of rural small villages far from the national electric grids Electrical loads in such villages are mostly small and can be covered by means of photovoltaic PV generators which are economically more feasible than extending the electric grid or using diesel electric generators Since PV has been rarely used in Palestine this paper is devoted to investigating the potential of PV applications in Palestine identifying the barriers for prevalence of PV applications as in other countries and demonstrating the reliability and feasibility of utilizing PV systems by presenting the test results of a PV system by supplying a rural clinic with its power demands A method for designing the PV power system respecting the local environmental conditions is presented in this paper The results of the measurements carried out over two years verify the reliability of the applied method The illustrated test results show how far the PV-power generation can be matched with load demands and state of battery charge even during periods of low solar radiation This could be achieved by respecting the local weather parameters in the illustrated sizing method Long term field experience in designing testing and operation of PV projects outside Palestine is presented in this paper Energy Efficiency Improvement by Raising of Power Factor at Industrial Sector in Palestinehttp://blogs.najah.edu/staff/emp_3029/article/Energy-Efficiency-Improvement-by-Raising-of-Power-Factor-at-Industrial-Sector-in-PalestinePublished ArticlesThe industrial sector in Palestine represent 15 of the total electric power consumption while the power losses in distribution network amount to 8 and the average power factor amount to 07 Implementing of a project aiming at energy efficiency improvement in industrial sector which included wide range of diversified power measurements had led to creating this paper Measurement results had shown that power losses in the distribution network are mainly caused due to low power factor in the industrial and residential sectors varying in the range 065 t 08 After improvement of the power factor in two factories as Demonstration Project ChS evaluation of measuring results show that the annual saving after installation of the compensation unites and improving the PF to 095 will be more than the total cost of the proposed capacitor units ie the simple pay pack period will be less than one year The electrical losses in the distribution network and transformers will be reduced to 25 by improving the power factor in the industrial sector to 095 is possible This percentage corresponds to 59914000 kwh or to money saving of 6657111 US I year From environmental points of view the mentioned energy saving corresponds to a reduction of CO2 emission amounting to 64707120 kgyear This result is not only applicable for Palestinian electrical network but also for other countries where similar conditions are prevailingPower Losses Reduction in Low Voltage Distribution Networks by Improving the Power Factor in Residential Sectorhttp://blogs.najah.edu/staff/emp_3029/article/Power-Losses-Reduction-in-Low-Voltage-Distribution-Networks-by-Improving-the-Power-Factor-in-Residential-SectorPublished ArticlesThe residential sector in Nablus - Palestine represent 48 of the total electric power consumption while the power losses in it amount to 81 Implementing of a project aiming at energy conservation in households which included wide range of diversified power measurements had led to creating this paper Measurement results had shown that power losses in the residential sector are mainly caused due to low power factor of the household - loads varying in the range: 055 - 075 After developing a proper mathematical model representing the power losses in the residential sector which represents a main load to the low voltage distribution network in Ch4 evaluation of measuring results show that an energy saving of 5318 by improving the power factor in the households to 095 is possible This percentage corresponds to 3242430 kwh year or to money saving of 353035 US year This result is not only applicable for Nablus electrical network but also for other Palestinian cities where similar conditions are prevailing