Performance of SPV Electricity Generation System

IJSTE - International Journal of Science Technology & Engineering | Volume 2 | Issue 08 | February 2016 ISSN (online): 2349-784X

Performance of SPV Electricity Generation System A. F. Sherwani Department of Mechanical Engineering Faculty of Engineering and Technology, Jamia Millia Islamia, New Delhi, 110025

Abstract The performance of solar photovoltaic electricity generation system can be ascertained by considering three parameters namely, electricity generation by the plant, greenhouse gas emission from the plant and life cycle cost analysis of the plant. Present work takes into account the electricity and greenhouse gas emission only. To formulate the directional design protocols, parameters which affect the output of the plant are identified and their values are varied to study their effect on the performance. Various parameters so identified are Tilt angle of the module (β), Geographical location of the plant i.e latitude (), Average daily radiation, Type of cell used (Amorphous, Mono crystalline, Polycrystalline), Green House Gas(GHG) emission of energy mix per kWh. Keywords: Geographical location, GHG emission and solar photovoltaic ________________________________________________________________________________________________________ I.

INTRODUCTION

The performance of solar photovoltaic electricity generation system can be ascertained by considering three parameters namely, electricity generation by the plant, greenhouse gas emission from the plant and life cycle cost analysis of the plant. Present work takes into account the electricity and greenhouse gas emission only.

To formulate the directional design protocols, parameters which affect the output of the plant are identified and their values are varied to study their effect on the performance.

Various parameters so identified are Tilt angle of the module (β), Geographical location of the plant i.e latitude (),Average daily radiation, Type of cell used (Amorphous, Mono crystalline, Polycrystalline),Green House Gas(GHG) emission of energy mix per kWh Based on the above parameters estimation of the radiation level received then PV array sizing is done and corresponding storage system is designed. Embodied energy is evaluated for the plant and in the last life cycle cost analysis is done.

The angle of tilt is varied from 15⁰-45⁰, radiation level is varied from 4-6 kWh/m2 and the area of the plant is taken to be 1000m2.Analysis is done for three types of module namely amorphous, mono crystalline and polycrystalline .The electricity mix for India at present is 0.4 which selected for design, and corresponding GHG emissions of energy mix per kWh is taken to be 600.Total embodied energy and CO2 emissions of both types of solar photovoltaic plants namely Stand alone and Grid Interactive system is calculated. Calculations are made for all five cities i.e Delhi (=280), Mumbai (=180), Bangalore (=120), Ladhak (=340) and Jodhpur (=260) one from each climatic zone.

After ascertaining the value of average daily radiation received the electrical output (kWh/year) is calculated for each city using the relation: Electrical output (kWh/year) =Ht*Area of PV Plant*hcell*TCF*hout hcell: Cell efficiency TCF: Temperature correction factor, taken as 0.7 hout: Output efficiency Cell efficiencies are taken as 0.07, 0.107, 0.137 for amorphous, monocrystalline and poly crystalline cells respectively.

Capacity of the plant (kW) is then calculated taking into account that there are sixty-five days on an average where the output from the plant may be zero to due adverse climatic conditions and total sunshine hours available are eight.

Capacity of plant (kW) = Electrical output (kWh/year)/300/8 It is calculated for different values of H g varying from 4-6 kWh/m2 and peak value is taken as capacity of the plant given as kWp. Electrical output from the plant is calculated for every city namely Delhi, Mumbai, Bangalore, Ladhak, and Jodhpur for four different tilt angles (β=150,250, 350,450) and for all three cell types amorphous, monocrystalline and polycrystalline.

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Performance of SPV Electricity Generation System (IJSTE/ Volume 2 / Issue 08 / 030)

II. ELECTRICAL OUTPUT Electrical output from the plant is calculated for all five different locations, =28º, 18º, 12 º, 34 ºand 26 º, four different Tilt angles β=15º, 25º, 35º and 45º and for three different cells amorphous, mono crystalline and polycrystalline. Three different values of radiation Hg i.e. 4, 5 and 6 kWh/m2/day are considered.

The following Figures 1 shows the variation of electrical output (kWh/year) with respect to tilt angle for, =28º. This is for all types of cell and radiation level.

Effect of tilt angle & others at location =28º Results were obtained showing variation of electrical output for different types of cells, and radiation level H g of 4, 5, 6 kWh/m2/day, with respect to tilt angle at location =28º. This is shown in consolidated form in Figure 1

Fig. 1: Effect of tilt angle, type of cell and radiation level on electrical output (kWh/year) for location with =280.

Polycrystalline

Monocrystallin Amorphous e

Table - 1 An overview of results generated for maximum electrical output (kWh/year) at different locations(), tilt angle, type of cells and different radiation level. β Cell Type Electrical Output (Hg=4) Electrical Output (Hg=5) Electrical Output (Hg=6)  28 35 59990 75896 91802 18 25 55452 69692 83931 12 15 54043 67707 81372 34 35 61742 78233 94723 26 25 58758 74216 89702 28 35 91700 116013 140327 18 25 84763 104228 128295 12 15 82608 103496 124383 34 35 94738 119584 144791 26 25 89817 113445 137117 28 35 117410 148541 179671 18 25 108528 133451 164266 12 15 105770 132513 159257 34 35 120839 153113 185386 26 25 114999 145253 175561

III. GREENHOUSE GAS (GHG) EMISSIONS Figures 2 show the variation of GHG emissions in g-CO2 per kWh with respect to GHG emissions of energy mix per kWh taken to be 500, 600 & 700 for both grid interactive and standalone system and tilt angle (β) 15 0 and given location (=28º).

Effect of Energy Mix and others at Location =28º with Tilt Angle Β=150 for Grid Interactive Systems: Results as obtained after varying Emission with respect to energy mix for different cell technology, radiation level, tilt angle β=150 has been obtained specifically for Grid Interactive system at location =28º . The same is shown in Figure 2

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Performance of SPV Electricity Generation System (IJSTE/ Volume 2 / Issue 08 / 030)

0.16 4,A

Emissions(kg/kwh)

0.14

5,A 0.12

6,A 4,M

0.1

5,M

0.08

6,M 0.06

4,P

0.04

5,P 500

600

700

6,P

GHG/kwh Fig. 2: Variation of emission (kg/kWh) with respect to GHG emissions of energy mix per kWh for different cell type and radiation level at =280 and β=150 for GI system.

Effect of Energy Mix and others at Location =28º with Tilt Angle β=150 for Standalone Systems: Results were obtained after varying Emission with respect to energy mix for different cell technologies, radiation level, tilt angle β=150 has been obtained specifically for standalone system (SPAV system) at location =28º . The same is shown in Figure 3.

Emissions(kg/kwh)

0.16

4,A

0.14

5,A

0.12

6,A

0.1

4,M

0.08

5,M 6,M

0.06

4,P

0.04 500

600 GHG/kwh

700

5,P 6,P

Fig. 3: Variation of emission (kg/kWh) with respect to GHG emissions of energy mix per kWh for different cell type and radiation level at =280 and β=150 for GI system.

IV. ANALYSIS Emissions increase when there is an increase in GHG of energy mix per kWh from 500-600-700 and are maximum for monocrystalline cell at Hg=4 and minimum for polycrystalline cell at Hg=6 for both grid interactive and stand alone system.

Emissions decrease with increase in tilt angle (β) and are found to be minimum for β=35º and on further increase of tilt angle it again increases.

For grid interactive system at Hg=4, Amorphous cell emissions varies from 92.1-110.5-128.9 g-CO2/kWh, monocrystalline cell emissions varies from 102.5-123-143.5 g-CO2/kWh and for polycrystalline at it varies from 81.3-97.6-113.9 g-CO2/kWh given β=15º. Similar values are also obtained for stand alone system also.

The results of emissions g-CO2/kWh for =28º at different tilt angles with respect to GHG of energy mix per kWh from 500600-700 for both grid interactive and stand alone system for different cells amorphous, monocrystalline and polycrystalline are summerised below in Table 2, 3 and 4

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Performance of SPV Electricity Generation System (IJSTE/ Volume 2 / Issue 08 / 030)

700

600

500

700

600

500

700

600

500

Table - 2 An overview of results generated for variation of emissions(kg/kWh) with respect to GHG emissions of energy mix per kWh for different radiation levels and for both GI and SPAV systems for amorphous cell.

Emissions Emissions Emissions Emissions Emissions Emissions Β GHG GI SPAV GI SPAV GI SPAV Hg=4 Hg=4 Hg=5 Hg=5 Hg=6 Hg=6 15 0.0921 0.0945 0.0732 0.0751 0.0607 0.0623 25 0.0894 0.0918 0.0709 0.0727 0.0587 0.0602 35 0.0890 0.0913 0.0703 0.0722 0.0581 0.0597 45 0.0907 0.0930 0.0715 0.0734 0.0591 0.0606 15 0.1105 0.1134 0.0878 0.0901 0.0728 0.0748 25 0.1073 0.1102 0.0850 0.0873 0.0704 0.0722 35 0.1068 0.1096 0.0844 0.0866 0.0698 0.0716 45 0.1088 0.1117 0.0859 0.0881 0.0709 0.0728 15 0.1289 0.1323 0.1025 0.1051 0.0850 0.0872 25 0.1252 0.1285 0.0992 0.1018 0.0821 0.0843 35 0.1246 0.1279 0.0985 0.1011 0.0814 0.0835 45 0.1270 0.1302 0.1002 0.1028 0.0827 0.0849 Table - 3 An overview of results generated for variation of emissions(kg/kWh) with respect to GHG emissions of energy mix per kWh for different radiation levels and for both GI and SPAV systems for monocrystalline cell.

Emissions Emissions Emissions Emissions Emissions Emissions β GHG GI SPAV GI SPAV GI SPAV Hg=4 Hg=4 Hg=5 Hg=5 Hg=6 Hg=6 15 0.1025 0.1049 0.0814 0.0833 0.0675 0.0691 25 0.0995 0.1019 0.0788 0.0807 0.0653 0.0668 35 0.0990 0.1014 0.0783 0.0801 0.0647 0.0662 45 0.1099 0.1033 0.0796 0.0815 0.0657 0.0673 15 0.1230 0.1259 0.0977 0.100 0.0811 0.0830 25 0.1195 0.1220 0.0946 0.0969 0.0783 0.0802 35 0.1188 0.1210 0.0939 0.0961 0.0776 0.0795 45 0.1211 0.1239 0.0955 0.0978 0.0789 0.0808 15 0.1435 0.1469 0.1140 0.1167 0.0946 0.0968 25 0.1394 0.1426 0.1104 0.1130 0.0914 0.0936 35 0.1387 0.1419 0.1096 0.1100 0.0906 0.0927 45 0.1413 0.1446 0.1115 0.1141 0.0921 0.0942 Table - 4 An overview of results generated for variation of emissions (kg/kWh) with respect to GHG emissions of energy mix per kWh for different radiation levels and for both GI and SPAV systems for Polycrystalline cell.

Emissions Emissions Emissions Emissions Emissions Emissions β GHG GI SPAV GI SPAV GI SPAV Hg=4 Hg=4 Hg=5 Hg=5 Hg=6 Hg=6 15 0.0813 0.0837 0.0646 0.0665 0.0536 0.0552 25 0.0790 0.0813 0.0626 0.0644 0.0518 0.0533 35 0.0786 0.0809 0.0621 0.0639 0.0513 0.0529 45 0.0801 0.0824 0.0632 0.0650 0.0522 0.0537 15 0.0976 0.1005 0.0775 0.0798 0.0643 0.0662 25 0.0948 0.0976 0.0751 0.0773 0.0622 0.0640 35 0.0943 0.0971 0.0745 0.0767 0.0616 0.0634 45 0.0961 0.0989 0.0758 0.0781 0.0626 0.0645 15 0.1139 0.1172 0.0905 0.0932 0.0751 0.0773 25 0.1106 0.1139 0.0876 0.0902 0.0725 0.0747 35 0.1100 0.1133 0.0870 0.0895 0.0719 0.0740 45 0.1121 0.1154 0.0885 0.0911 0.0730 0.0752

Results from Tables 2, 3 and 4 shows that emissions are more for Standalone system as compared to Grid Interactive system for every value of GHG energy mix per kWh. Polycrystalline cell has the least emission followed by Amorphous and highest is with Mono crystalline cell. With the increase in the value of radiation there is a decrease in emission for both Grid Interactive and Standalone systems.

The range of emission for Grid Interactive system with varying tilt angle from 15 0-450 with Amorphous cell Hg=4 kWh/m2/day GHG=500, is found to be 92.1-90.7 g-CO2/kWh. This increases with increase in GHG and is found to be in the range of 128.9-127.0 g-CO2/kWh for GHG =700. Emissions reduce with increase in H g and above range is found to be 60.7-59.1 g-CO2/kWh at GHG=500 and 85.0-82.7 g-CO2/kWh for GHG=700 at Hg=6 kWh/m2/day.

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For Standalone system the range is 94.5-93.0 g-CO2/kWh at GHG=500 and increases to 132.3-130.2 g-CO2/kWh for GHG=700 at Hg=4 kWh/m2/day. For Hg=4 kWh/m2/day the range is 62.3-60.6 g-CO2/kWh at GHG=500 and 87.2-84.9 gCO2/kWh at GHG=700.

The range of emission for Grid Interactive system with varying tilt angle from 15 0-450 for Mono crystalline cell Hg=4 kWh/m2/day GHG=500, is found to be 102.5-109.9 g-CO2/kWh and it increases with increase in GHG and is found to be in the range of 143.5-141.3 g-CO2/kWh for GHG =700. Emissions reduces with increase in H g and above range is found to be 67.565.7 g-CO2/kWh at GHG =500 and 94.6-92.1 g-CO2/kWh for GHG=700 at Hg=6 kWh/m2/day.

For Standalone system the range is 104.9-103.3 g-CO2/kWh at GHG=500 and increases to 146.9-144.6 g-CO2/kWh for GHG=700 at Hg=4 kWh/m2/day. For Hg=4 kWh/m2/day the range is 69.1-67.3 g-CO2/kWh at GHG=500 and 96.8-94.2 gCO2/kWh at GHG=700.

The range of emission for Grid Interactive system with varying tilt angle from 150-450 for Polycrystalline cell Hg=4 kWh/m2/day GHG=500, is found to be 81.3-80.1 g-CO2/kWh and it increases with increase in GHG and is found to be in the range of 113.9-112.1 g-CO2/kWh for GHG =700. Emissions reduces with increase in H g and above range is found to be 53.652.2 g-CO2/kWh at GHG =500 and 75.1-73.0 g-CO2/kWh for GHG=700 at Hg=6 kWh/m2/day.

For Standalone system the range is 83.7-82.4 g-CO2/kWh at GHG=500 and increases to 117.2-115.4 g-CO2/kWh for GHG=700 at Hg=4 kWh/m2/day. For Hg=4 kWh/m2/day the range is 55.2-53.7 g-CO2/kWh at GHG=500 and 77.3-75.2 gCO2/kWh at GHG=700.

V. CONCLUSION Optimal sizing of SPV electricity generating systems which have the flexibility of standalone and grid interactive systems has been undertaken. The parameterization of solar cells along the calculation of radiation, array sizing requirement of storage system and its design along with emission and cost analysis has been undertaken. This has importance in view that one would be able to calculate the embodied energy of the complete plant and its component also. With change of technology the component can be change and embodied energy can be re estimated that is why embodied energy for component has been taken. This provides a framework for the design along with different location in the next chapter Extensive calculations were performed on the equation based model. Results so obtained were consolidated. At different values of location, variation in tilt angle, emission level and other related factors figures were made. Five locations were considered with four variations in tilt angle. Three different types of contemporary cell technologies have been considered alongwith three different radiation levels. This chapter will enable in deciding the type of systems one should opt under different conditions.

The above Figures shows that electrical output is maximum for polycrystalline cell followed by monocrystalline and is minimum for amorphous cell for given Hg and at a particular location, also electrical output is maximum for a tilt angle plus minus 5º of latidude. Electrical output is in the range of 48,000 to 62,000 kWh/year at Hg=4, 60000 to 79000 kWh/year at Hg=5,and 72000 to 94723 kWh/year at Hg=6 for amorphous cell. For monocrystalline cell it is in the range of 73000 to 95000 at Hg=4,92000 to 120000 kWh/year at Hg=5 and 110000 to 145000 kWh/year. For polycrystalline it is in the range of 94000 to 121000 kWh/year at Hg=4, 118000 to 154000 kWh/year at Hg=5 and 141000 to 186000 kWh/year and results are summarised in Table 1.

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