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Renewable Energy 50 (2013) 253e258

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Renewable Energy

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Study of economic viability of photovoltaic electric power for Quetta e Pakistan

Anjum Khalid a,*, Haroon Junaidi b

aDepartment of Mechanical Engineering, NED University of Engineering and Technology, Karachi 75300, PakistanbAdam Smith College, Stenton Campus, Glenrothes, Scotland, UK

a r t i c l e i n f o

Article history:Received 15 July 2011Accepted 20 June 2012Available online 24 July 2012

Keywords:Solar energyPhotovoltaicFeasibility analysisRETScreen

* Corresponding author. Tel.: þ92 21 99 261 261x2E-mail addresses: akhalid@neduet.edu.pk, anjumk

0960-1481/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.renene.2012.06.040

a b s t r a c t

This study assess the feasibility of photovoltaic based power plant; for this purpose best site for thelocation of the project is determined by comparing monthly average daily global solar radiation data ofeight Pakistani cities and Quetta city is chosen for the 10 MW plant. RETScreen simulation of the powerplant shows that about 23.206 GWh of electricity can be generated in a year if one axis tracking methodis employed. At a total cost of $50 m, 50% debt ratio, 9% discount rate the proposed PV plant generateselectricity at a rate of $0.157/kWh. The investigation shows that presently the PV based electricity isabout 30.8% more expensive as compared to grid supplied electricity. Emission analysis demonstratedthat the proposed PV power plant avoided carbon dioxide production by 17,938 tons/year. The analysisshows that presently the proposed PV power plant is not feasible if only economic factors are considered.Sensitivity analysis demonstrates that if total installed cost of the plant is about $35 m then the cost ofpower from photovoltaic plant will be equal to grid supplied electric power without any subsidy.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Reasonably priced electricity, among other factors, plays a veryimportant role in the industrialization, reduction of poverty andsocial uplift of a developing country. Presently Pakistan suffers froma severe electric power shortage which is one of the causes ofstunted industrial growth, high unemployment rate and occasionalunrest. Pakistan’s energy resources consist of thermal, hydro andnuclear power. Thermal power is generated from oil and gas basedpower plants. These plants are aging and a significant number ofthem are single cycle with low efficiencies thus fuel use per unit ofelectricity generated is high. Consequently electric power gener-ated from these plants is costly. The import of oil constitutesa major portion of the total import bill of the country.

Traditionally electricity had been cheap in Pakistan due toavailability of abundant natural gas as fuel for power plants. Withthe increase in population natural gas use has increased thatresulted in rapid depletion rate of this resource. To keep the price ofelectricity low government has traditionally subsidized electricity.Due to rising fuel price and demands from international fundingagency government has realized that subsidy is non sustainableand damaging to national economy it has started increasing electricpower tariff [1,2] that truly reflect the cost of generation. Fig.1 showthe electricity tariff change with time for domestic consumers whoconsume from 301 to 700 kWh/month of electricity.

347.halid@yahoo.com (A. Khalid).

All rights reserved.

To overcome chronic power shortage problem government isplanning to mine large deposits of coal for electric power genera-tion. Power generated from the coal is cheap but it causes damageto land, water and air frommining and combustion of coal in powerplants. Apart from global polluting impact of carbon dioxideparticulate material, oxides of sulfur and ash in the exhaust gasesproduced by coal fired power plants directly affect the nearbyecosystem and human population. Alternative to fossil fuel basedpower plants are renewable energy resources like photovoltaicswhich are clean and sustainable. Distributed nature of photovoltaicbased power plants ensures that power is produced where it isrequired. This aspect of PV is very suitable for far flung areas wherenational grid has not reached.

PV is a promising, nonpolluting renewable source of electricity;it is mature technology with more than 50 years proven record asa reliable electricity generation method [3]. The modular nature ofPV power system allows its use in small and large systems withequal ease. PV installations have grown at very high rate of over 42%in the last thirty seven years Fig. 2 [3,4]. Adequate sunlight isubiquitous and present in predictable amounts almost everywhereconsequently photovoltaic power system can be installed in widestgeographic locations [5]. Mass production of photovoltaic panel,competition among manufacturers, and improvement in efficiencyhas resulted in significant module price drop. Graph given in Fig. 3highlights the decreasing trend of PV module price in the lasteleven years [6].

A survey of the literature in the area of electric power produc-tion from photovoltaic based power plants revealed that relatively

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small number of studies have been performed that addressed theprospects of photovoltaic power in Pakistan [7,8]. Present investi-gation is an attempt to fill this gap and provide an analysis of PVpower project. Aim of this work is to select the best location fora 10 MW photovoltaic power plant from eight cites of Pakistan andto estimate the financial viability of the PV farm and establish itsgreen house gas emission avoidance capacity.

2. Solar energy potential of Pakistan

Pakistan is a sun-belt country with more than 300 sunny days ina year making it a suitable place for exploitation of solar energy asa sustainable resource. To choose the site with largest electricitygeneration potential from photovoltaic power plant eight citieswere selected from different geographical locations in Pakistan.These cities included Quetta, Lahore, Faisalabad, Hyderabad, Hunza,Chitral, Badin and Ormara. Annual average daily global solar radi-ation values for these cities were obtained from RETScreen climatedatabase which is derived from NASA global climatic database.

Analysis of radiation data revealed that Quetta has the highestaverage daily global radiation on a horizontal surface of 5.54 kWh/m2/day and Lahore has the lowest value of 4.68 kWh/m2/day.Important parameters such as geographic location, solar insolation,capacity factors, and electric power production potential of 8 citiesof Pakistan were determined from RETScreen and are provided inTable 1. Due to its best power potential and proximity to largepopulation center Quetta solar site was chosen for the analysis ofthe proposed 10 MW electric power project. Hourly variation ofglobal solar radiation over a year for Quetta is shown in Fig. 4. Theweather data in the form of Typical Meteorological Year (TMY2) filefor Quetta was obtained from METEONORM global meteorologicaldatabase [9].

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3. Methodology

RETScreen renewable energy system simulation software is verysuitable for performing preliminary evaluation of renewableenergy projects and was used for present study. RETScreen is Excelbased software which was created by Canmet Energy ResearchCentre, Natural Resource Canada and is available free of cost [10].RETScreen is validated software [11]; it is easy to use and providesaccurate result of energy yields within 0e6% of actual value [12].This software contains a number of worksheets for performingdetailed project analysis. RETScreen project includes Energy Model,Cost Analysis, Emission Analysis, Financial Analysis and Sensitivityand Risk Analyses sheets.

Subsequent sections describe the use of RETScreen software tosystematically establish the feasibility of the photovoltaic powerplant.

3.1. Estimation of electric power generation

Energy production assessment is performed in the EnergyModel sheet of RETScreen which requires input of project location,photovoltaic module type, solar tracking mode, miscellaneouslosses of array and inverter. Quetta is located in the mountainousarea of Balochistan province in north-west of Pakistan at a height of1621 m. It has latitude of 30.2� North and longitude of 66.9� East.Quetta receives annual average daily solar insolation of 5.54 kWh/m2/day on horizontal surface, a one axis tracking surface receives7.9 kWh/m2/day while a two axis tracking surface receives8.17 kWh/m2/day insolation. Quetta has an annual average ambienttemperature of 15.7 �C; it receives an average of 64.7% directradiation and 35.3% diffuse radiation. This implies that an appre-ciably large proportion of incident solar radiation is direct or beamradiation.

For sunny regions like Quetta crystalline PV modules are moresuitable while thin film photovoltaic modules work better underdiffused radiation conditions. PV modules based on crystallinesilicon also have low age derating value of power as compared tothin film modules [13] which means that the decline in PV powerplant electricity generation capacity is relatively small over its lifetime. Commercial crystalline PV modules are more efficient ascompared to amorphous or thin film modules. Accordinglycomparatively small module and land area is required for theproject. Consequently for electricity generation mono crystallinesilicon modules e mono-Si-HiP-190BE2 e were chosen from theproduct database of RETScreen software. The chosen mono crys-talline silicon panels have conversion efficiency of 16.1% andtemperature coefficient of 0.40%/�C. For the proposed 10 MWpower plant the collector area was estimated to be 62,112 m2.

Table 1Average solar radiation and power production potential of 8 cities of Pakistan.

Quetta Lahore Faisalabad Hyderabad Hunza Chitral Badin Ormara

Elevation (m) 1621 217 186 26 4269 4115 7 208Latitude (Degrees N) 30.3 31.4 31.4 25.4 36.3 36 24.7 25.2Longitude (Degrees E) 66.9 74.4 73.1 68.4 74.6 71.8 68.8 64.6Average ambient temperature (�C) 18.0 24.4 23.8 26.5 �5.6 �1.2 27 24.6Radiation-horizontal surface (kWh/m2/d) 5.54 4.68 5.03 5.27 4.45 4.85 5.24 5.33Radiation-1-axis tracking surface (kWh/m2/d) 7.9 6.39 7.07 7.03 6.44 7.12 7.02 7.16Capacity factor-1-axis tracking array (%) 26.5 20.9 23.1 22.7 23.7 25.6 22.8 23.4Electricity generated (GWh/year) 23.2 18.3 20.2 19.9 20.8 22.4 19.9 20.5Electric energy generated as percentage of Quetta 100 82.4 87.1 85.8 89.6 96.5 85.8 88.4

A. Khalid, H. Junaidi / Renewable Energy 50 (2013) 253e258 255

Tracked PV systems have cost advantage in regions withirradiation values above 1800 kWh/m2/year [14], Quetta receives anaverage solar radiation of 2023 kWh/m2/year hence it is a suitablesite for tracked PV projects. In RETScreen Energy Model threeoptions of solar tracking are available for PV power projects. Theyinclude fixed array tilt, one axis tracking and two axis tracking. PVprojects based on fixed tilt arrays are less costly and one and twoaxis tracking systems are progressively more expensive due toadded cost of sun tracking mechanisms. Single and two axestracking modules intercept larger amount of solar radiation incomparison to fixed tilt system.

RETScreen suggests that when PV array is facing due south, inthe northern hemisphere, and array tilt angle is equal to locallatitude then annual solar energy yield is maximized. Using Quettalatitude of 30.2� and due south orientation the annual energyproduction from fixed tilt PV farm was assessed. One and two axistracking PV plant energy yields were also determined. Resultshowed that energy yield from the PV plant progressivelyincreased. It was also determined that the difference in energy yieldof one axis and two tracking PV plants was very small while theprice difference between the two systems was significant. Elec-tricity production cost from one axis tracking plant was found outto be the lowest amongst the three types of plant. In view of thesefacts a one axis tracking PV farm was chosen for economic andenvironmental study.

RETScreen has to be supplied realistic values of different lossesthat occur during normal operation of photovoltaic power system.These losses may arise due to such factors as module mismatch,operating temperature, dirt deposition on module or soiling and dcto ac conversion etc. RETScreen calculates temperature losses forthe specified module from temperature coefficient available in itsdatabase for the module selected by the user. Quetta located in thearid mountainous region of Pakistan has considerable dust in the

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atmosphere thus deposition of dust on modules could causesignificant losses. A value of 10% was chosen for array losses frommiscellaneous sources such as dust losses etc. Inverter is used tochange dc power coming from PV arrays into ac electricity thisprocess has some inefficiencies. Modern inverters are very efficientand an efficiency of 95% was chosen for inverter from RETScreendatabase. Different PV system inputs are given in Table 2.

3.2. Assessment of financial viability

Financial analysis involves, among other things, inputs such ascapital cost, electricity export rate, required rate of return, elec-tricity export escalation rate, base case fuel price escalation rate andinflation rate. RETScreen Financial Analysis Sheet also requiresproject annual costs and credits.

Based on the component price determined from previousstudies [15,16] a capital cost of $40 million was used in RETScreenfor the 10 MW PV South facing plant with fixed array tilt of 30.2�.The price of one axis tracking PV power plant was estimated to bethe sum of the price of fixed orientation plant and price of $1/W fortracker which is equivalent to a total tracker cost of $10 m. Thus theinitial cost of one axis tracking PV plant came out to be $50m. In thecase of two axis tracker PV power plant the tracker price was 36.8%higher than the price of one axis tracker [17] therefore the cost oftracker was estimated as $13.68 m that resulted in plant initial costof $53.68 m.

To encourage investment in renewable projects government ofPakistan offers several incentives such as income tax exemptionand premium tariff rates for these projects [18,19]. Consequently noincome tax and tax depreciation was included in the economicanalysis of the PV project. Presently tariff paid to independentpower producers (IPP) in Pakistan for bulk electricity purchase byutilities has a rising trend and is comparable to $0.12/kWh [20].Considering this fact an electricity export rate of $0.12/kWh waschosen for the 30 year lifespan of the project. Over the last 14 yearthe electricity price has grown at rate of about 5% per annum, Fig. 1.Using this as a guide price escalation rate of 5% per year was chosenfor this project. RETScreen suggests a range of 0e90% debt ratio forrenewable energy projects. In light of this a 50% debt ratio wasemployed in the financial analysis of the project.

Table 2PV power plant inputs.

Technical inputs

Quantity Input valueCapacity of the power plant 10 MWAverage solar radiation for Quetta 5.54 kWh/m2/dayTracking system One axisPV module temperature coeff 0.40%/�CPV module conversion efficiency 16.1%Miscellaneous PV array losses 10%Invertor losses 5%

Table 3PV power plant financial inputs.

Financial inputs

Variable Input valueProject life 30 yearsElectricity export rate $0.12/kWhElectricity export escalation 5.0%/yearDebt ratio 50%Debt term 10 yearsInflation rate 8%Discount rate 9%

Table 4Important indicators for three modes of PV array orientation.

Sun tracking mode

South facing-fixedtilt

One axis Two axis

Generated power (GWh/yr) 17.713 23.206 23.922Cost of tracking ($/Watt) 0 1.0 1.386Capital cost of plant (m$) 40 50 53.68O&M cost ($/yr) 335,000 500,000 500,000Cost of electricity (¢/kWh) 15.8 15.7 16.0

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Fixed tilt PV power plant is expected to have low O&M costs ascomponents with moving parts like trackers are not used. Howeverregular cleaning of dust from panel in such plants is required aswell as occasional replacement of inverters. An O&M cost of$0.335 m/yr that also includes replacement cost of inverter wasestimated for of PV plant. The other two types of power plants thatuse trackers will incur additional repair or replacement cost oftrackers in their lifetime. Thus the O&M cost of these power plantsis the O&M cost of fixed tilt type power plant and additional repairand replacement cost of trackers. A cost of operation and mainte-nance of $0.5 m was estimated for one and two axes tracking PVpower plants, which is comparable to the O&M cost used in earlierstudies [16,21].

In free market economy a PV power plant like any other enter-prise has to earn profit on investment. Required rate of return oninvestment is the rate used to discount future cash flows to obtaintheir present value. RETScreen suggested range of required rate ofreturn on investment in electric utility projects for North America is3%e18%; it was used as guide for choosing discount rate or requiredrate of return for this project and a value of 9% was chosen from thisrange for the project. Other input parameters for the proposed PVpower plant were chosen carefully after communication withworkers in relevant fields and scrutinizing current economictrends and their projection over the 30 year life of the project.

In the financial analysis no emission reduction credit or cleanenergy production income is assumed. However within the sensi-tivity analysis clean energy production income of $0.036/kWh hasbeen assumed and its effect on the feasibility of the project werestudied. Table 3 shows the detail of the important financial inputs.

3.3. Harmful emission avoidance

Total electricity production in Pakistan in 2010 was 95.6 TWhout of which fossil fuel based thermal power plants’ contribution to

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electricity generation was 64.4 TWh. It implies that 67.3% of theelectricity was generated from fossil fuel based power plants [22].Due to decreasing local natural gas production oil has becomea dominant fuel for power plants. These plants produce carbondioxide, particulate mater and other harmful pollutants equallyharming local and global environment. RETScreen calculatedspecific carbon dioxide production rate of the base case powerplant was 0.773 tonCO2/MWh. This value of carbon emission waschosen in light of the low efficiency of the thermal electric powerplants in Pakistan.

4. Results and suggestions

RETScreen simulation showed that the PV power plant withsouth facing arrays of 30.2� tilt produced 17.713 GWh/yr ac electricpower while the one axis tracking plant produced 23.206 GWh acelectricity in a year. Against this value the farm with a two axistracking arrays generated 23.922 GWh/yr. This means that powerobtainable from a one axis tracking PV farm is 31% higher than thepower from a similar sized farm with south facing 30.2� tilt arrays.On the other hand power generation improvement from one axistracking to two axis tracking is marginal and is only 3.08%. Monthlypower generation capacities of the three types of PV farms areshown in Fig. 5. Power generation capacities and other importantindicators of these farms are provided in Table 4. It is obvious fromthese indicators that one axis tracking PV power plant generatesleast cost electricity.

Financial analysis result showed that at initial cost of $50millions and electricity export rate of $0.12/kWh, and electricityexport escalation rate of 5% the one axis tracking plant net presentvaluewas�$14.9million. Equity payback period was 18.5 years andinternal rate of return (IRR) on equity was 5.5% which was less thanthe required rate of return of 9%. A negative value of NPV demon-strated that the project is financially not feasible. Similarly otherproject indicators highlighted that at present the economics of thisplant is not very encouraging for its installation. Table 5 emphasizessome important financial indicators.

RETScreen emission reduction analysis showed that theproposed PV power plant avoided carbon dioxide production by17,938 tons/year. This was equivalent to 538,140 tons of avoidedcarbon dioxide in the lifetime of the plant.

Table 5Financial indicators of the proposed PV power plant.

S. No Output variable Output value Suggested optimumvalue

1 Net present value �$14.9 million Any positive value2 Energy production

cost$0.157/kWh Should be equal to or lower

than electricity tariff3 Benefit-cost ratio 0.41 1>4 Internal rate of

return on equity5.5% IRR � Required rate of return

5 Year to positivecash flow

18.7 years Investors’ acceptedvalue < 10 years

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Fig. 6. Sensitivity analysis results of the 10 MW photovoltaic power plant showing comparison of original values and new values of important input variables. New values are forwhich NPV is zero and project is economically feasible.

A. Khalid, H. Junaidi / Renewable Energy 50 (2013) 253e258 257

Despite its economic non feasibility implementation of this PVpower project can be achieved if feed-in-tariff (FiT) concept isadapted in Pakistan. FiT ensures guaranteed power purchase fromrenewable power producer at premium price. The elevated price ofrenewable electricity is spread over all the consumers. This resultsinto slight increase in electricity bill to the consumers. Peopleaccept higher price of electricity if it is supplied uninterrupted andis obtained from non polluting resources. Feed-in-tariff providesa better way of starting and sustaining renewable energy projectsin the country. FiT should be provided to renewable energy projectoperators until such plants can compete economically with fossilfuel based power plants. The required FiT for the present PV powerplant is basically equal to or greater than the cost of electricitygeneration estimated by RETScreen which is $0.157/kWh.

A photovoltaic power project does not require any fuel andoperation and maintenance cost is low, major annual cost is therepayment of loan and interest on the loan. Electricity generationcost drops significantly when the PV project loan is fully paid up. Itis estimated that when all the loan has been paid up in about 18years then electricity cost of the proposed plant will be about ¢2.15/kWh since the only expenditure of running the plant will then bethe O&M cost. This value has been calculated by dividing the O&Mcost of $0.5 m/yr by 23.206 � 106 kWh of electricity produced ina year by the plant.

5. Sensitivity analysis

Sensitivity analysis on RETScreen was undertaken with the aimto determine the values of economic input variables that couldmake this PV power plant feasible for Quetta. During sensitivityanalysis one input variable was gradually changed and its effect onoutput variables was observed while the others inputs were keptconstant. The most important economic variables that stronglyaffected net present value, payback period, and internal rates ofreturn included project capital cost, electricity export rate, elec-tricity export escalation rate, solar radiation and clean energyproduction income. Any positive value of NPV is regarded asa suitable indicator for the selection of power project.

Simulation showed that an initial total cost of $35millionwouldmake the plant financially feasible. The analysis further highlightedthat for electricity export rate of $0.157/kWh the PV power plantwill become financially viable. Analysis showed that feasibility ofthis project is also strongly dependent on electricity export esca-lation rate. Rising fossil fuel price will ensure that electricity in thecountry will become more and more expensive with the passage

time. If the electricity export escalation rate increases from presentvalue of 5% to 7.08% then project will become financially feasible.Furthermore a clean energy production income of $0.037/kWh willmake the project financially viable. Fig. 6 presents sensitivityanalysis results in graphical form showing comparison of originalvalues and new values of important input variables. New values arefor which NPV is zero and project is economically feasible.

6. Conclusion

This study showed that one axis tracking PV power plantgenerates the cheapest electricity and has potential to generate23.206 GWh electric power in a year at Quettawhich is the sitewithhighest solar insolation. While Lahore being the worst site cangenerate 18.3 GW/year from the proposed PV power project. Whilemost of the area of Pakistan has the potential to generate powernearly equal to power generation potential of Quetta site. Theelectricity obtained from this clean power source will cost $0.157/kWh and will help abate local and global pollution. The plant willhelp avoid production of 17, 938 ton of carbon dioxide per year.However presently high initial cost makes this project unfeasibleeven at the best site in Pakistan despite the fact that O&M cost ofthis 10MWplant is $0.5m/year as no fuel is needed. However someeconomic factors have the potential to change this situation infuture. First is the falling price of PV modules and the secondequally important development is the rising electric power tariff inPakistan. These two factors will hopefully bring PV based electricityprice equal to grid supplied electricity in future. However if feed-in-tariff of $0.157/kWh or above is provided then it will make this PVpower project economically viable in Pakistan now.

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