Forecasting the potential of solar energy harvest in Kangar

Forecasting the Potential of Solar Energy Harvest in Kangar

Syafawati A.N.1, Salsabila A.2, Farhana Z., Arizadayana Z., Razliana N., Norjasmi A.R., Muzaidi O., S. Akhmal School of Electrical System Engineering, School of Microelectronic Engineering Complex,

Universiti Malaysia Perlis (UniMAP), 02600 Arau, Perlis, Malaysia

[email protected], [email protected]

Abstract-This paper provides a case study in solar radiation and the potential evaluation of solar energy harvesting at 6.431°N, 100.185°E, in Kangar, Perlis, Malaysia. As a state located in the Northern region, Perlis is highly potential in the development of a solar energy harvesting system. However,in order to start harvesting the solar energy as an alternative electricity utility source, it is essential to investigate the amount of solar radiation received at the location beforehand. This paper, defines the parameters of solar radiation and shows the geometrical relationship of its natural resources in order to determine the potentiality. The value of solar radiation was collected from the installed weather station and from the calculation based on the equations.

Keywords- solar, radiation, energy, harvest

I. INTRODUCTION Solar radiation is the most important natural energy

resource because it drive all environmental processes acting on the surface of the Earth. The sun provides the Earth with an enormous amount of energy [1]. Solar energy is primarily transmitted to the Earth by electromagnetic waves, which is also represented by photons. Solar radiation emission from the sun distributed into the space appears in the form of electromagnetic waves that carry energy at the speed of light. The solar radiation can be absorbed, reflected, or diffused by solid particles at any location in space, but particularly on the earth, its arrival depends on many activities such as the weather, climate, agriculture, and socioeconomic movement. Besides that, the incoming irradiation at any given point takes different shapes depending on the geometry of the earth, its distance from the sun, geographical location at any point on the earth, astronomical coordinates, and the composition of the atmosphere. A significant fraction of the solar radiation is absorbed and reflected back into space through atmospheric events and consequently the solar energy balance of the earth remains the same [2].

The radiation emitted to the ground depends on the geometric relationship of the Earth orbiting the Sun. The position of the Sun, in any moment at any place on Earth, can be estimated by using two methods. Firstly, using a simple equation where the inputs are; the day of the year, time, latitude, and longitude. Secondly, by using complex algorithms providing the exact position of the Sun [1]. Since, the solar radiation varies based on location and time, this paper only focuses on Kangar, the capital state of Perlis (6.431°N, 100.185°E) within the month of March until August of the year 2011. Various data of the weather were collected and recorded in Centre of Excellence in Renewable Energy, Universiti Malaysia Perlis (UniMAP), Kangar, Perlis. Perlis, located at the top Northern state in Peninsular Malaysia shared the same border with Thailand as shown in Fig. 1. Meanwhile, the south

area is neighboring to the state of Kedah. Perlis covers an estimated area of 793.99km2, and it experiences the tropical monsoon and northeast monsoon winds from the Gulf of Siam. These two monsoons occur along the year where the dry season takes place from January until April, while the rainy season is from May until December [3]. Furthermore, Malaysia is one of many Asian countries that is located in equatorial regions which received an abundance of sunlight and rainfall the whole year. The average temperature of Perlis is around 21 – 32 degrees Celsius.

Fig. 1: Map of Perlis State [3]

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Zenith

NCP

ϕ

δ ω θz

W

ENS

γs

ϕ

Path of the Sun on the equinoxes αs

II. DATA AND METHOD

A. Sun-Earth Geometrical Relationship The Sun’s position is described with respect to a horizontal

surface on Earth at any time, however other angles on the Earth’s coordinates also need to consider. These angles are; declination (δ), solar altitude (αs), zenith (θz), solar azimuth (γs), and hour angle (ω) as described in Fig. 2 [1]. These angles listed are being used to obtain the value of radiation falls on a horizontal and tilt surface. From the calculated angle based on latitude and longitude known for Kangar, it is then used to plot the sun chart and sun path for certain days.

Fig. 2: Position of the Sun in the sky relative to the solar angles

1) Declination Angle: The declination angle, δ on the celestial sphere is measured

northward or southward from the celestial equator plane. Lines of constant declination run parallel to the celestial equator and run in numerical values from +90° to -90°. Because of the Earth’s yearly orbital motion, the Sun appears to circle the ecliptic up to an inclination of 23.45° to the celestial equator, -23.45° < δ < 23.45° with δ = 0° at the equator for the equinoxes, -23.45° on the December solstice, and +23.45° on the June solstice [1].

Several formulations to determine declination in degrees have been reported such as Spencer (1971), Brichambaut (1975) and Cooper (1969) [1]. However, formulation derived from Cooper is used broadly because of the simplicity factor. The formula is as shown below:

where n is day of the year and the value of the declination angle is in degree.

2) Hour Angle: The hour angle is the angle through which the Earth must

be rotated to bring the meridian of the plane directly under the sun. In other words, it is the angular displacement of the Sun east or west of the local meridian, due to the rotation of the Earth on its axis at 15° per hour. The hour angle is calculated based on equation below:

ω = ( ST – 12 ) x 15°

where ST is solar time.

The Sun angles are obtained from the local solar time, which differs from the local standard time. The relationship between the local solar time and the local standard time (LST) is:

Solar Time = LST + ET + ( lst – llocal ) x 4 min/degree

ET is the equation of time, which is a correction factor that accounts for the irregularity of the speed of Earth’s motion around the Sun. While lst is the standard time meridian and llocal is the local latitude [3].

ET(minutes) = 9.87sin 2B – 7.53cos B – 1.5sin B

where B = 360 (n – 81) / 364 degrees.

3) Zenith Angle: In most latitudes, the Sun will never be directly overhead;

like it does within the tropics. Since the zenith is the point directly overhead and 90° away from the horizon, the angle of the Sun relative to the line perpendicular to the Earth’s surface is called the zenith angle, θz and it derived from [1]:

4) Solar Altitude: The length of the day varies for all latitudes throughout the

year and therefore, the solar altitude, αs also changes hourly and daily. This angle can be calculated in terms of declination, latitude and hour angles by using the equation below [1]:

where ϕ is the latitude

5) Azimuth Angle: Solar azimuth angle, γs is the angle in the horizontal plane,

between the line due south and the projection of beam radiation on the horizontal plane. By convention, the angle is taken to be positive and negative respectively [4]. The expression of the azimuth as shown below:

B. Solar Radiation Solar radiation from the sun from the space enters the

atmosphere at the space-atmosphere interface, where the ionization layer of the atmosphere ends. Afterwards, a certain amount of solar radiation or photons are absorbed by the atmosphere, clouds, and particles in the atmosphere, some amount is reflected back into the space, while some is absorbed by the Earth’s surface. The radiation from the sun, arriving on the ground directly is called direct or beam radiation. While, the radiation scattered out from th the beam radiation by gases and aerosols inclusding dust particles is called the diffused radiation. Reflected radiation, in the meantime, is mainly reflected from the terrain and is therefore more important in mountainous areas [2]. The solar radiation path is shown in the Fig. 3.

( )⎟⎠⎞

⎜⎝⎛ += 284

365360sin45.23 nδ

ωφδδφθ coscoscossinsincos +=z

ωφδδφα coscoscossinsinsin +=s

zs θ

δωγsin

cossinsin =

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Fig. 3a-c : Solar radiation paths. a. Direct. b. Diffuse. c. Reflected. [2]

1) Extraterrestrial Radiation: Solar irradiance, I (W/m2), is the rate at which radiant

energy is incident on a unit surface. The solar radiation varies according to the orbital variations. The change in extraterrestrial solar radiation can be calculated by taking into account the astronomical facts according to the following equation:

where n is the number of the day corresponding to the given date.

As shown in Fig 3, the solar radiation during its travel through the atmosphere toward the Earth's surface meets various phenomena which changes with time. It is useful to define a standard atmosphere “clear” sky and calculate the hourly and daily radiation that will be received on a horizontal surface under these standard conditions [2].

The atmosphere transmittance for beam radiation, τ is given in an exponentially decreasing from depending on the altitude, A and zenith angle as:

⎟⎟⎠

⎞⎜⎜⎝

⎛−

+= z

c

bea θτ cos where the estimation of constant a, b, c for the standard atmosphere with 23 km visibility as given for altitude less than 2.5 km [2].

( )( )

( )22

2

5.201858.02711.0

5.6005958.05055.0

600821.04237.0

Ac

Ab

Aa

−−=

−−=

−−=

where A is the altitude of the observer in kilometers. The atmospheric transmittance in the equation above can be replaced by site specific value. Hence the solar radiation on a horizontal plane can be estimated by: I = I0τ

2) Solar Energy: Once the solar irradiance, I on the ground is known, then,

the solar radiation perpendicular to the horizontal surface is calculated. The monthly average daily values of the extraterrestrial irradiation on a horizontal plane, Ĥ0 and the maximum possible sunshine duration, Ŝ are two important parameters that are frequently needed in solar energy application [2]. The value of Ĥ0 for a given day can be computed by:

⎟⎠⎞

⎜⎝⎛ +××

×= δφπωωδφ

πsinsin

3602sincoscos360024H0

^ss

ssI

where ωss is the sunset hour angle.

( )δφω tantancos 1 ×−= −ss

While, the value of monthly average daily maximum

possible sunshine duration S0 for a given day and latitude can be obtained below:

( )δφ tantancos152 1

0 ×−= −S

3) Hargreaves Samani Modeling

Various equations are available for estimating Reference Crop evapotranspiration (ETO) and most important parameters in estimating ETO are; the temperature and solar radiation. From the equation define for ETO, Hargreaves Samani has recommended a simple expression to estimate solar radiation, H [5]:

minmax0 TTHkH H −=

where H is in MJm-2, Tmax and Tmin are mean daily maximum and minimum air temperature in °C respectively, H0 is extraterrestrial radiation in MJm-2 which is a function of latitude and day of the year and kH is an empirical coefficient, and the value to be 0.16 for inland regions and 0.19 for coastal regions[5].

III. DATA AND METHOD ANALYSIS This section discusses the mentioned equations in previous

part.

A. Sun Path Diagrams In this subsection, the combination of all equation used in

the geographical relationship between Sun and Earth is shown. The importance of each angle of solar is applied and illustrated in the sun path and sun chart diagram for certain day of measured and calculated data.

⎥⎦

⎤⎢⎣

⎡⎟⎠⎞

⎜⎝⎛+=

365360cos033.010

nII

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Fig. 4: Sun path diagram for December until June in Kangar, Perlis [6]

Fig. 5: Sun path diagram for June until December in Kangar, Perlis [6]

Fig. 6: Sun Chart diagram for December until June in Kangar, Perlis [6]

Fig. 7: Sun Chart diagram for June until December in Kangar, Perlis [6]

The projection of the Sun’s path on the horizontal plane is called a sun path diagram. These diagrams are very useful in determining shading phenomena associated with solar collector, windows and shading devices. The point at the intersection of the corresponding δs and ωs lines represents the instantaneous location of the Sun. The solar altitude is read from concentric circles in the diagrams. While the azimuth is from the scale around circumference of the diagram [3].

B. Solar Radiation In order to determine the solar radiation at 6.431°N,

100.185°E, there are two methods used to solve and compare the results. The first method; is using the expression as shown in the previous part which is from formulation and calculation. The formulation used is based on few researchers in the same field of studies. As stated earlier, solar radiation varies with location, day in the year and time. Based on the calculated solar radiation, it shows the connection between Sun-Earth and the movement of Earth in orbiting the Sun for each single minutes along the year. The second method is through data collected from the Davis Vantage Pro2 Weather Station. The weather station located in front of the Research Cluster, collected and recorded weather data, particularly the estimation of the total solar radiation received in every minute of the day. The approximation of the error from formulation is considered to overcome the uncertainty received.

Fig. 8: Solar radiation scattered from 60 to 235 of the year

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The trend illustrated in Fig. 8 is show the solar radiation that recorded from March until end of August for the year 2011. The calculated of solar radiations are scattered linearly followed by differentiate between maximum and minimum temperature as used from the Hargreaves Samani Modelling.

IV. CONCLUSIONS Overall, this paper has shown the relationship between the

formulation with the measured data. From the observed and calculated of solar radiation, it show that the average of solar radiation received are above 300 Wm-2. With the average weather condition in Perlis, it noted that have a potential to harvest the solar energy.

ACKNOWLEDGMENT This work was supported by Exploration Research Grant

Scheme (ERGS) from Exploration of Photovoltaic arrangement structure through solar concentrator to optimize energy harvested. The authors gratefully acknowledge the contributions and cooperation from member of School of System Electrical Engineering and Centre of Excellence for Renewable Energy (CERE), Universiti Malaysia Perlis, (UniMAP) for their work on the original version of this document.

REFERENCES [1] F. Robert, G. Majid, and C. Alma, Solar Energy: Renewable Energy and

the Environment, CRC Press, 2010.

[2] S. Zekai, Solar Energy Fundamentals and Modeling Techniques Atmosphere,Environment, Climate Change and Renewable Energy, Springer-London, 2008.

[3] D. Yogi, K. Frank, F. Kreider, Principles of Solar Engineering, Taylor & Francais, 2000.

[4] Tiwari G.N., Ghosal M.K. Fundamental of renewable energy sources. New Delhi: Alpha Science; 2007.

[5] A.N. Syafawati, I. Daut, M. Irwanto, & etc., Weibull and Hargreaves Methods to Determine the Wind and Solar Energy – Case Study, Applied Mechanics and Materials, Vol. 110-116 (2012), pp. 2030-2033.

[6] V. Frank, K. Rich, and H. Peter, Solar Radiation Monitoring Laboratory, University of Oregon. http://solardat.unoregon.edu (Retrieved online : 20 July 2012).

[7] Syafawati, A.N., Daut, I., Shema, S.S., Irwanto, M. & etc. Potential of wind and solar energy using Weibull and hargreaves method analysis, Power Engineering and Optimization Conference (PEOCO) 2011 5th International, 2011, p. 144-147.

[8] Samani, Z. Estimating solar radiation and evapotranspiration using minimum climatologitcal data (Hargreaves –Samani equation). ASCE Journal of Irrigation and Drainage, 126(4), 2000, p.1-13. Available online at http://cagesun.nmsu.edu.

[9] Theo. C.C. Equation for estimating global solar radiation in data sparse regions. Renewable Energy 33 (2008), p. 827-831.

[10] Daut, I., Irwanto, M., Irwan, Y.M. & etc. Potential of solar radiation and wind speed for photovoltaic and wind power hybrid generation in Perlis, Northern Malaysia. Power Engineering and Optimization Conference (PEOCO) 2011 5th International, 2011, p. 148-153.

Noor Syafawati Ahmad received her B. Elect. Eng. From Univeristi Teknologi Tun Hussein Onn Malaysia (UTHM) in 2008 and MSc in Electrical Systems Engineering from Universiti Malaysia Perlis (UniMAP) in 2010. She is currently a lecturer in the School of Electrical System Engineering at UniMAP. Her research interest is in renewable energy system especially solar engineering.

Salsabila Ahmad obtained her B. Eng (Hons) in Electrical and Electronics Engineering from University of Tenaga Nasional in 2001. She then joined a company involved in automation, and worked as an engineer. In 2005, she left the company to join Universiti Malaysia Perlis in the School of Electrical System Engineering. Then, she continued her studies in MSc specializing in Renewable Energy in Universiti Putra Malaysia. Now, she is attached in the Centre of Excellence of Renewable Energy, Universiti Malaysia Perlis. Her research interest includes automation,

renewable energy, wind and solar cells. Farhana Zainuddin was born in Kangar, Perlis, in 1987. She received her degree in Bachelor of Engineering in Electrical from the Universiti Sains Malaysia, in 2010. She then joined the Centre of Excellence for Renewable Energy in Universiti Malaysia Perlis as a MSc student. Her main interest is in solar system.

Arizadayana binti Zahalan received her BEng (Hons) from Universiti Sains Malaysia in 2001. From 2001 until 2009, she worked as an engineer at a tyre manufacturing company. She is currently a vocational training officer in the School of Electrical System Engineering at University Malaysia Perlis (UniMAP). She is also a member of the Centre of Excellence for Renewable Energy, University Malaysia Perlis (UniMAP), Perlis, Malaysia. Her research interest includes microcontroller applications and renewable energy particularly wind and

solar power.

Nurul Razliana Abd Razak was born in Kedah, Malaysia on November, 08, 1987. She is a postgraduate student in Electrical System Engineering at University of Malaysia Perlis (UniMAP). She received her Bachelor (Hons) of Electrical Engineering at University Tun Hussein Onn Malaysia (UTHM) in 2010. Her research interest is on renewable energy particularly on solar, wind and hybrid system.

Norjasmi Abdul Rahman obtained his Diploma in Electrical Engineering (Electronic) from Universiti Teknologi Mara in 2001 before receiving his B. Eng (Hons) in Industrial Electronic Engineering from University Malaysia Perlis in 2007. He then joined B.Braun Medical Industries as Automation Engineer. In 2008, he continued his studies in MSc in Aalto University (formerly known as Helsinki University of Technology), Finland. Currently, he joined University Malaysia Perlis as a lecturer and his research interest includes power electronic converters, wind and solar

technologies.

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Muzaidi Othman received his Diploma in Eng. (Power Electronic and Control) from Polytechnic Sultan Abdul Halim in 2001. He then received his degree in B. Eng in Electrical System from UniMAP in 2007 and M. Eng in Industrial Electronics and Control from Universiti Malaya in 2010. His research interest includes renewable energy conversion, industrial control and power electronic.

Syed Akhmal S. Jamalil attained his B. Eng (Hons) in Electronics Industrial from Universiti Malaysia Perlis, Malaysia in 2008. He got his practical training at Petronas Fertilizer, Kedah then joined Universiti Malaysia Perlis as a Teaching Engineer in the School of Electrical System Engineering. Now, he continued his studies in M.Eng focusing in Electrical Power System and still attached as Teaching Engineer in Microcontroller Design course and Analog Electronics. His research interest includes Microcontroller Design, Power System for Economic Dispatch Solution

and Industrial Electronics.

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