DOI : 10.17577/IJERTV4IS090304
- Open Access
- Total Downloads : 353
- Authors : Abikoye O. E. , Ogunmekan T. , Olaboye Y. O.
- Paper ID : IJERTV4IS090304
- Volume & Issue : Volume 04, Issue 09 (September 2015)
- Published (First Online): 18-09-2015
- ISSN (Online) : 2278-0181
- Publisher Name : IJERT
- License:
This work is licensed under a Creative Commons Attribution 4.0 International License
Determination of Optimum Tilt Angle of Photovoltaic (PV) Solar Module for Each Month of the Year: A Case Study of Offa, Kwara State, Nigeria
Abikoye, O. E.*
Mechanical Engineering Department Federal Polytechnic Offa
Offa, Kwara State, Nigeria
Ogunmekan, T.
Mechanical Engineering Department Federal Polytechnic Offa
Offa, Kwara State, Nigeria
Olaboye, Y. O.
Mechanical Engineering Department Federal Polytechnic Offa
Offa, Kwara State, Nigeria
Abstract – The optimum orientation and tilt angle with horizontal plane is principal to the performance of photovoltaic (PV) solar module. This paper zeros in on ascertaining the best tilt angle for each month throughout the seasons of the year in Offa, Nigeria; situated at latitude: N8° 7.9075 longitude: E4° 42.7352, so as to fully harness the power of the sun and sustain optimal solar power generation all year round. The Solar panels were positioned for angles 00
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800 in variance of 100 apart and were oriented towards North and South respectively. The voltages generated by each panel at various degrees apart were recorded on a daily basis from 09:00 to 18:00 GMT+1 West African Time throughout the year using a multimeter. The data obtained were analyzed and the results showed that, the best tilt angle for each month of the year from January to December varies. Thus, the results were presented in graphical and tabular forms.
Key Words: Tilt Angle, Solar Energy, Pv Modules, Sun Hour.
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INTRODUCTION
There has been a remarkable increase in the demand and use of energy in many countries due to rapid economic growth and improved life standard [1].Thus, the daily and increasing use of conventional energy and fossil fuel both in domestic and industrial activities over time has a negative impact on our environment and is on its way to exhaustion [2, 3]. While it is declining in major developed countries at a geometrical rate, its declination is at a slow pace in many developing countries and majorly in Africa.
Research has however shown that, one of the main renewable energy resources which are eco-friendly and can curb the negative impact of fossil fuels and environmental problem such as global warming, release of greenhouse gases (GHG) and other pollutants that are facing this age, is Solar energy (2, 4, 5). The present day climate change
problems have led to the search for renewable energy sources that are free and eco-friendly in order to maintain a green environment [6, 7].
One of the applications of renewable energy technology (Green energy) is the installation of photovoltaic (PV) systems that generate power without emitting pollutants and requiring no fuel [8]. The sun which powers this system is approximately 150 million km from the earth. It has a surface temperature close to 5500oC and it emits radiation at a rate of 3.8x1023kW per second on an average daily basis [9]. It is worth to note that, only a small fraction of its radiations actually reaches the surface of the earth. Therefore, harnessing this fraction for daily activities becomes very vital in the reduction of the use of hydrocarbon energy sources and maintaining a green environment.
Both the orientation and tilt angles have significant effects on the magnitude of the solar radiation reaching the surface of a panel or collector and consequently affect its performance [10]. The magnitude of solar radiation received by solar panel or collector is a function of many factors such as atmospheric conditions, location latitude, load profile, optical and geometric properties, the sunrise hour angle, the azimuth angle, macro- and micro-climatic conditions, geographical position, and period of use as noted by [11, 12]. The tilt angle is defined as the angle between the solar panel surface and the horizontal plane. The orientation of the solar panel is also defined with respect to the horizontal plane and it is the angle between the line due south and the projection of the solar panel normal to the surface on the horizontal plane [13]. It was reported in the work of [14] that the orientation of the PV surface is described by its tilt angle and the direction, both related to the horizontal. Thus, in the northern hemisphere,
the optimum orientation is when facing south or when facing north in the southern hemisphere and the optimum tilt angle depends only on the latitude.
It has been found that, for every location on earth with specific radiation characteristics, there is an optimal tilt angle for the best solar energy reception. Thus, the solar radiations from the sun can be maximized by varying the tilt or slope of solar panels to an angle at which the solar radiations are maximum. The optimum orientation and tilt angle of a PV panel to the horizontal is central to the design, installation and consequently the generation of peak power needed. This is due to the fact that both the orientation and tilt angle change the solar radiation reaching the surface of the panel or collector.
Several authors have used different simulation methods to establish and determine the tilt angle for specified areas all round. Reference [15] examined the optimum tilt angle for Cyprus. For maximum radiation the results were calculated by varying tilt angle form 0° to 90° with the increment of 10°. Reference [14] analyzed the theoretical aspects of choosing a tilt angle for the solar flat-plate collectors used at ten different stations in the world and makes recommendations on how the collected energy can be increased by varying the tilt angle. Reference [16] found that the optimum tilt angle changes between 0 (June) and 61 (December) throughout the year. In winter (December, January, and February) the tilt should be 55.7, in spring (March, April, and May) 18.3, in summer (June, July, and August) 4.3, and in autumn (September, October, and November) 43. Reference [17] stated that for Indian stations, the calculations are based upon the measured values of monthly mean daily global and diffuse solar radiation on a horizontal surface.
Reference [18] determined optimum tilt angle and orientation for solar photovoltaic arrays in order to maximize incident solar irradiance exposed on the array, for a specific period of time. While [19] presented a mathematical procedure to compare the optimum tilt angles of solar collectors through monthly diffused radiation and actual monthly diffused radiations. The best orientation for solar collectors in Izmir was south facing. Reference [20] gave a method to calculate the optimum tilt angle of an equator-facing solar collector in the heating seasons. Reference [21] calculated the optimum tilt angle for equator-facing solar collectors, based on only beam radiation. Reference [22] has carried out an analysis to determine the optimum tilt angle by considering the effects of the latitude, number of glass covers, clearing index and the solar reflectivity.
Since there is no definite value given by researchers for the optimum tilt angle. Further review of different researchers works show that there is a wide range of optimum tilt angle as recommended by different authors, and they are particular for specific locations. It is therefore practical and necessary to orient solar panel or collector at an optimum tilt angle which maximizes the most amount of collected or trapped energy for each month of the year; Hence, the need for this research.
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METHODOLOGY
For the purpose of this research, nine panels were set up and oriented towards the Northern hemisphere from the month of May to the month of September then back to face the southern hemisphee. This is due to the fact that the sun faces the southern hemisphere between the months May and September since Nigeria is situated at latitude: N8° 7.9075 longitude: E4° 42.7352. The panels were arranged in such a way that same measure of radiation fall on them without the shadow of one casting on the other. A multimeter was used to record the different voltage readings from each panel for each hour of the day from 09:00 to 18:00 GMT+1 West African Time. The data recorded were then collated and an average for each month was calculated so to determine the best tilt for each month of the year. The analyzed results were then presented in graphs.
Apparatus Used In This Experiment
The following apparatus were used to determine the best tilt angle.
-
MULTIMETRE: used to indicate the voltage.
-
SOLAR PHOTOVOLTAIC PANEL: Solar Photovoltaic panel is a power source having non linear internal resistance and an array which is formed by series/parallel combination of Solar Photovoltaic cells to attain a desired voltage and current level.
-
ELECTRIC CABLES: are insulated conductors used to carry electricity from one place to another.
-
PROTRACTOR: used to determine the angle of inclination i.e. (tilt angle).
-
COMPASS: used to determine the direction of the North Pole or South Pole.
Experimental Setup
The experimental set up consists of nine mono crystalline solar collectors rated 10Watt each along with nine volt meters to keep voltage logs as shown in Fig. 1. Each solar collector (C) was mounted at a different tilt angle as follows; C1:00, C2:100, C3:200, C4:300, C5:400, C6:500,
C7:600, C8:700, C9:800, as shown in Fig. 2. Data were captured between the hour of 9 a. m. and 6 p. m. each day for period of 12 months.
Fig. 1 Multimetre showing voltage readings of each panel
Fig. 2 Arrangement of the solar panels at different elevations
-
-
DISCUSSION
Presented in the below graphs are the results of the data collected in order to ascertain the best tilt angle for maximum power output in each month of the year. Thus, from Fig. 3 presented below, the tilt angle that gave the maximum voltage output is at 600 with 19.8196volts for the month of January. It was observed that tilt angle 200 is closest to it with 19.8085volts as well as tilt angles 10, 30, 40, and 50 degrees. It was also noted that the lowest generated voltage was 16.3629 which is fairly alright. Fig. 4 shows that, for February, tilt angle 600 is the best tilt angle for that month as 19.8245volts was recorded. Tilt angle 200 with 19.70volts is closest to it. The lowest voltage recorded was 16.4270volts. From Fig. 5, 19.752volts which was the highest volt recorded was
against tilt angle 200 for the month of March. The record taken for the month of April reveals that the best tilt angle was at 600 with 20.1559volts while the lowest volt recorded was for angle 800 with 17.5134volts as shown in Fig. 6.
Also, Fig. 7 shows that tilt angle 600 with 20.135volts stand the best tilt for the month of May as against the 16.845volts recorded for tilt angle 800. Average Voltage of 20.152volts was recorded for tilt angle 600 in the month of June as the highest voltage. The Average voltage (17.154volts) from tilt angle 200 is closest to it as in Fig. 8. Fig. 9 which gives the average recorded data for the month of July has shown that the best tilt angle is angle 600 with 20.1896volts. While tilt angle 800 with 16.9016volts has the lowest voltage, it was noted also that tilt angle 200 with
20.0272volts is closest to the best tilt angle. The best tilt angle for the month of August is 200 which has 19.895volts as in Fig. 10.
Furthermore, as shown in Fig. 11, the tilt angle with the highest recorded volts was 200 with 19.8932volts. Tilt angles 40, 50, and 60 degrees volts are closest to that recorded for angle 200 for the month of September. For the
month of October, as shown in Fig. 12, the best tilt angle was found to be 200 as 19.5962volts was recorded.
Finally, from Fig. 13 and Fig. 14, the best tilt angles for both the month of November and December is 500 with 19.6666volts and 19.6762volts respectively. There is no significant difference in the voltages recorded between each tilt angle for both months.
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
16.36296296
17.51666667
19.81962963
19.40555556
19.37333333
19.26555556
19.80851852
19.19888889
18.22555556
0 5 10 15 20 25
Average Voltage (V)
Fig. 3: Tilt Angle vs Average Voltage for the month of January
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
16.42708333
17.63054167
19.82458333
19.27508333
19.3005
19.07041667
19.7
19.28354167
18.25125
0 5 10 15 20 25
Average Voltage (V)
Fig. 4: Tilt Angle vs Average Voltage for the month of February
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
16.1572
17.34
19.5856
19.4332
19.3092
18.9416
19.752
19.608
18.1732
0 5 10 15 20 25
Average Voltage (V)
Fig. 5: Tilt Angle vs Average Voltage for the month of March
80°
70°
Tilt Angles
60°
50°
17.51344
17.78884
19.27344
20.15596
40°
30°
20°
10°
0°
19.71424
19.99196
19.867
19.63248
19.19517333
16 16.5 17 17.5 18 18.5 19 19.5 20 20.5
Average Voltage (V)
Fig. 6: Tilt Angle vs Average Voltage for the month of April
80°
70°
Tilt Angles
60°
50°
16.845
17.58561111
19.245
20.135
40°
30°
20°
10°
0°
19.63166667
19.77666667
19.81527778
19.65888889
19.01722222
15 16 17 18 19 20 21
Average Voltage (V)
Fig. 7: Tilt Angle vs Average Voltage for the month of May
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
17.154
17.78536
20.152
19.38853333
19.58453333
19.719
20.01576
19.70288
19.06904
15 16 17 18 19 20 21
Average Voltage (V)
Fig. 8: Tilt Angle vs Average Voltage for the month of June
80°
Tilt Angles
60°
40°
20°
16.9016
17.4848
20.1896
19.4148
19.6116
19.31356
20.02724
19.6288
0° 18.852
15 16 17 18 19 20 21
Average Voltage (V)
F ig. 9: Tilt Angle vs Average Voltage for the month of July
80°
Tilt Angles
60°
40°
20°
0°
15.62773077
16.30423077
19.25580769
19.44961538
19.33769231
17.93934615
19.895
18.96807692
17.10307692
0 5 10 15 20 25
Average Voltage (V)
Fig. 10: Tilt Angle vs Average Voltage for the month of August
80°
70°
Tilt Angles
60°
50°
40°
15.7344
16.5548
19.5708
19.6872
19.6436
30°
20°
10°
0°
18.244
19.8932
18.9472
17.4728
0 5 10 15 20 25
Average Voltage (V)
Fig. 11: Tilt Angle vs Average Voltage for the month of September
80°
Tilt Angles
60°
40°
20°
0°
15.68296296
16.54148148
19.34481481
19.48925926
19.18896296
18.10185185
19.5962963
18.57766667
17.29444444
0 5 10 15 20 25
Average Voltage (V)
Fig. 12: Tilt Angle vs Average Voltage for the month of October
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
15.81125
19.45291667
19.66666667
19.16166667
18.43583333
19.47166667
18.64291667
17.43208333
0 5 10 15 20 25
Average Voltage (V)
Fig. 13: Tilt Angle vs Average Voltage for the month of November
80°
70°
Tilt Angles
60°
50°
40°
30°
20°
10°
0°
15.82
17.0237037
19.55740741
19.6762963
19.25
18.55148148
19.53851852
18.69111111
17.5437037
0 5 10 15 20 25
Average Voltage (V)
Fig. 12: Tilt Angle vs Average Voltage for the month of December
-
CONCLUSIONS
-
From the analyzed data in this research work carried out in Federal Polytechnic, Offa, Kwara State; the conclusions drawn in reference to the best tilt angle which gave the maximum voltage for each month of the year are summarized in Table 1.
Table 1 Summary of Monthly Solar Panel Tilt Angle
|
MONTH |
BEST TILT ANGLE (Degrees) |
|
January |
60 |
|
February |
60 |
|
March |
20 |
|
April |
60 |
|
May |
60 |
|
June |
60 |
|
July |
60 |
|
August |
20 |
|
September |
20 |
|
October |
20 |
|
November |
50 |
|
December |
50 |
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