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VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.comA SIZING TOOL FOR PV STANDALONE SYSTEMMohd Shawal Jadin, Intan Zalika Mohd Nasiri, Syahierah Eliya Sabri and Ruhaizad IshakSustainable Energy & Power Electronics Research, Faculty of Electrical & Electronic Engineering, Universiti Malaysia Pahang,Pekan, Pahang, MalaysiaE-Mail: [email protected] project aims to develop a software for sizing a standalone photovoltaic (PV) systems. The proposed tool hasthe capability to allow the user to employ meteorological data such as ambient temperature, irradiation data, and peak sunhour (PSH) in designing the PV system. Usually, a micropower system is designed to serve a specific load demand, in thiswork, the stand-alone PV is modelled with a particular load profile to ensure that the system meets required energydemand. The developed tool is used to determine the feasibility of the stand-alone system in terms of PV size and theestimated total power production. The tool developed with a built in database which stores different types of PV panels,batteries, charge controllers and inverters. The proposed sizing tool was validated based on the real data implemented onthe case study for a residential buildings.Keywords: photovoltaic, standalone system, solar radiation, sizing tool.INTRODUCTIONCarbon dioxide emissions are harmful anddangerous to living things. Based on Carbon DioxideInformation Analysis Centre (CDIAC), fossil fuelsproduced high emissions of carbon dioxide which is18.5% or 1551 million metric tons of carbon released fromfossil fuels in 2007 [1]. The energy produced by PVsystem is one of the clean energy sources that does notemit carbon dioxide. Currently, many research works havebeen carried out to reduce the emissions of carbon dioxidegenerated from fossil fuel power plants.Photovoltaic (PV) is a technology that convertssolar energy into direct current electricity without undergoany combustion process that may produce environmentallyharmful byproducts [2]. In general, the PV system can beclassified into stand-alone and grid connected system. Thestand-alone system is independent of the power grid henceit is supported by storage batteries or other auxiliarysupplies. Conversely, the grid connected system implies adirect connection to the electrical grid; therefore excessenergy produced by the PV source can be supplied to thegrid or otherwise [3].Simplicity of the standalone PV design is anadvantage of the system to meet the electricity demand.However, to design such simple system will definitely takea lot of time to complete the huge task of calculations.Other than that, manual calculations may easily incur largepercentage of errors. Therefore, the use of sizing tool canassist user although have a minimal knowledge about PVsystem in which they are able to design and predict theoutput gained from the PV installation. In this work, aresidential premise is used as a case study to validate theproposed system configuration.RELATED WORKThere are several works been done on PV sizingtool. Sulaiman et al. [4] proposed an intelligent method foroptimizing PV size in grid connected system. Evolutionaryprogramming (EP) was used to determine the optimal setof photovoltaic (PV) module and inverter. Ammar et al.[5] proposed an open source tool for characterization ofphotovoltaic power sources with respect to the state of thebattery, load change and climatic parameters variation.The software was developed based on standard algorithmsand models.The solar PV system performance depends uponsite parameters, system configuration and load parameters.Therefore, Kushika and Rai [6] presented a solar PVdesign expert system which determines a compositeparameter as a function of latitude and longitude. Theparameter combines both site and array characteristics toavoid the problem due to variability of severalclimatological parameters. Recently a MATLAB basedsoftware tool called PV.MY was developed by Khatib etal. [7] to find the optimal size of PV systems. Thesoftware features the capabilities of predictingmeteorological variables using artificial neural network(ANN) function.PV SIZING TOOL FRAMEWORKIn this work, the sizing tool is developed usingGUI platform based on MATLAB software to provide auser friendly interface. The tool can be used to findsuitable type of panel, inverter, battery and theconfiguration of PV array. The overall steps in this workare summarized in the flowchart shown in Figure-1 beginswith collecting data and ends with some analysis results onPV sizing performance.INVERTER SIZINGUsing this software, user may easily find thesuitable size of inverter that matches with the value ofmaximum AC load demand and AC surge load demand.The total number of inverter required is calculated usingthe following formula:Load assesment:(1)Sinv 30min Smax AC demand sfinv10727
VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.comThe apparent power of inverter during surge demand:Sinv surge Smax AC surge sfinv(4)(2)where,Number of inverter:(3)The battery bank capacity is derived fromwhere,(5)where,Revised battery capacity:(6)where,Total bank discharge current:(7)where,Ibank disch discharge current of battery bankNumber of batteries string in series:(8)where,Nseries bank number of batteries in series stringNumber of batteries string in parallel:(9)Figure-1. The overall steps in PV sizing tool.BATTERY SIZINGThe sizing of battery is based on the energyrequirement and capacity required daily. Currently, thereare 52 types of commercial batteries listed in the database.User can select any types of battery available to get theprediction value of batteries needed. The tool will displaythe possible maximum number of batteries that can fit therequired capacity. The total number of battery required iscalculated by using.where,PV MODULE SIZINGBasically, the number of PV module is calculatedbased on user requirement. The output from PV modulesshould be sufficient to support the energy requirement ofthe building. There are 122 types of PV module availablein the database and the new data specification can beadded manually. To calculate the size of PV module, two10728
VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.commethods can be used which are either to use the standardcharge controller or by using the charge controller withMPPT.SIZING BASED ON STANDARD CHARGECONTROLLERFor this method, the PWM charge controller isused as standard charge controller. There are 11 differentkinds of PWM charge controller and user can select anyfrom the list to get the prediction of module configuration.The output will display the number of PV modulesconnected in series as well as parallel. Total number of PVmodule required can be calculated using formula below:calculation steps are more complicated. The total numberof PV module is determined using formula below:Temperature derating factor:(15)(16)where,Temperature derating factor:(10)Operating Voltage Limit:(17)(11)where,(18)Corrected power output:(19)where,Corrected output current:(12)where:Sub-system efficiency:(20)where,Number of modules connected in series:(13)The number of modules connected in series stringwith the safety margin of 5% is given byNumber of modules connected in parallel:(14)where,SIZING BASED ON MPPT CHARGE CONTROLLERSimilarly, user can select the appropriate type ofMPPT charge controller. PV module. There are 14 typesof MPPT controller listed in the MS Excel database. Thesoftware output will show the PV configuration arrayrecommended. For this type of PV module sizing, the(21)where,and the number of modules connected in parallel string:(22)where,10729
VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.comNP respectively. Figure-3 shows the program for designingthe standalone PV system.number of strings of modules connected inparallel requiredHence, the total number of modules is:(23)where,CHARGE CONTROLLER SIZINGAs mentioned, the tool allows the user to choosebetween two types of charge controller, either PWM orMPPT type controller. The selection of charge controllersis based on maximum charging current from the PV arrayand the total current rating of the charge controller. Thetools will calculate the possible minimum number ofcharge controller based on the number of batteriesrequired using formula below:Figure-2. Main page of PV design tool.Total current rating of charge controller with thesafety factor value of 1.25 is given by(24)where,Number of charge controller:Figure-3. Standalone PV system design.(25)where,RESULTS AND ANALYSISThe result of this project consist of two partsbased on different methods used for charge controller. Theconfiguration of PV system sizing depends on the scenarioof case and type of equipment chosen by the user. In thiswork, a residential building in Pekan Pahang is chosen asstudy case to validate the feasibility of developedsoftware. The load of residential building is used tocalculate the load demand for a period of one year. Theamount energy produced by the PV system is calculatedbased on the value of load profile and efficiency of theinverter chosen. Figures-2 shows the main page of the PVsystem design tool for sizing the standalone PV system,calculation of load profile and database of PV modulesDESIGN BASED ON CASE STUDYThe design start with the calculation of the loadprofile of a building. User is required to fill in the loadprofile form to determine the total load demand. If the useralready has the load profile of the building, they candirectly insert the values in the sizing window. Forexample the load profile of case study is shown inFigure-4.Figure-4. Calculation of energy load profile.10730
VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.comANALYSIS OF THE PV SYSTEM DESIGNTo illustrate the ability of the tools, both types ofPV modules are compared to analyze the performance ofPV system in terms of energy prediction. Some of theinformation used in the case study are listed below:Table-1. Meteorological data of Pekan, Pahang, Malaysia.Information: Average AC Load (VAH) 56885.6 Total AC Power 8581.8 Wh AC surge load demand 35818.7 VA maximum AC load demand 28570 VA fmm 0.91 fdirt 0.95 fo 1.2 Tambient 32.025 C PSHpa 5hType of inverter: Solon Allegro 10/48Type of battery: Trojan L16REType of PV module: BP Solar BP3175 SCHOTT ASE-320DGF/5DType of standard charge controller: Plasmatronics PL20From the results obtained, the number of inverterSolon Allegro 10/48 required is 31 units. Meanwhile, typeof battery chosen is Trojan L16RE and total number ofbattery needed is 192 units. The tool also recommendedthat 24 batteries are connected in series and 8 batteries inparallel. As for the type of PV module, the BP SolarBP3175 is selected and the configuration recommended isthat 2 modules are connected in series and 88 strings ofmodules connected in parallel. For comparison, the PVmodule type SCHOTT ASE-320DGF/5D was also tested.The results recommended that 1 module is connected inseries and 69 strings of modules are connected in parallel.After sizing the PV system, the user can assessthe performance of the system based on the type ofinverter, battery, PV module and charge controller. In thisstudy, meteorological data measured in Pekan area used asgiven in Table-1. The performance of the PV systemdesigned is analyzed in terms of the types of PV modulechosen towards the energy generated per year. For the PVsystem using BP Solar BP3175, the energy generated peryear can be seen in Figure-5 while for SCHOTT ASE-320DGF/5D, the result is shown in Figure-6. For both PVsystem, the graphs show that the predicted energy yield(kWhpa) increases when the PSH (h) is higher.Figure-5. The performances of PV module design with BPSolar BP3175.Figure-6. The performances of PV module design withSCHOTT ASE-320-DGF/5D.Based on the type of PV modules, the energyproduced will increase when the number of module10731
VOL. 10, NO. 22, DECEMBER 2015ARPN Journal of Engineering and Applied SciencesISSN 1819-6608 2006-2015 Asian Research Publishing Network (ARPN). All rights reserved.www.arpnjournals.comincreased as illustrated in Table-2. The energy predicteddepends on the value of PSH, the configuration of PVmodule and the output power of PV module. In addition,the value of total energy predicted per year is comparedwith total energy required per year in order to evaluateability of the system in supplying the energy. Result inFigure-7 shows the total energy predicted per year ishigher than the total energy required. The energy producedby the PV system design is sufficient to cover the energyneeded by the building.Table-2. The energy produced based on differentconfiguration of PV modules.conveniently can use this tool to develop their own PVsystem.REFERENCES[1] T. A. Boden, G. Marland, and R. J. Andres. 2010.Global, regional, and national fossil-fuel CO2emissions.[2] S. C. Singh, Solar Photovoltaics : Fundamentals,Technologies and Applications. PHI Learning Pvt.Ltd.[3] D. P. Kaundinya, P. Balachandra and N. H.Ravindranath. 2009. Grid-connected versus standalone energy systems for decentralized power - Areview of literature. Renew. Sustain. Energy Rev.,Vol. 13, No. 8, pp. 2041–2050.[4] S. I. Sulaiman, T. K. A. Rahman, I. Musirin, S. Shaariand K. Sopian. 2012. An intelligent method for sizingoptimization in grid-connected photovoltaic system.Sol. Energy, Vol. 86, No. 7, pp. 2067–2082.[5] M. Ben Ammar, M. Ben Ammar, M. Chaabene, A.Rabhi and A. El Hajjaji. 2012. Characterization toolfor photovoltaic power sources. in 2010 18thMediterranean Conference on Control Automation(MED), pp. 1609–1613.[6] N. D. Kaushika and A. K. Rai. 2006. Solar PV designaid expert system. Sol. Energy Mater. Sol. Cells, Vol.90, No. 17, pp. 2829–2845.[7] T. Khatib, A. Mohamed and K. Sopian. 2012. ASoftware Tool for Optimal Sizing of PV Systems inMalaysia. Model. Simul. Eng. Vol. 2012, p. e969248.Figure-7. The energy generated per year (kWh).CONCLUSIONSIn order to fulfil the electricity demand, thestandalone PV system is an option to yield a feasibleenergy supply. The development of software tool to findthe practical sizing of the PV system is important to assistusers in minimizing the cost and time. In rural area ofPekan, Pahang; there is a potential to install the standalone PV system since the yearly solar irradiation and PSHare almost constant. The development of this softwareconsiders the solar irradiation, average ambienttemperature and PSH of the installation site. User withminimal knowledge on designing a standalone PV system,10732
The overall steps in PV sizing tool. BATTERY SIZING The sizing of battery is based on the energy requirement and capacity required daily. Currently, there are 52 types of commercial batteries listed in the database. User can select any types of battery available to get the prediction value of batteries needed. The tool will display
