1. INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING
International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
& TECHNOLOGY (IJEET)
ISSN 0976 – 6545(Print)
ISSN 0976 – 6553(Online)
Volume 4, Issue 1, January- February (2013), pp. 109-114 IJEET
© IAEME: www.iaeme.com/ijeet.asp
Journal Impact Factor (2012): 3.2031 (Calculated by GISI) ©IAEME
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MICROCONTROLLER BASED AUTOMATIC SOLAR POWER
TRACKING SYSTEM
1
Hemlata B. Nirmal, 2 Syed A. Naveed
1
P.G. Student, Electronics and Telecommunication Dept.
Jawaharlal Nehru Engineering College, Aurangabad, (M.S.) INDIA.
2
Electronics and Telecommunication Dept.
Jawaharlal Nehru Engineering College, Aurangabad, (M.S.) INDIA.
hemlatanirmal@rediffmail.com, sa_naveed01@rediffmail.com
ABSTRACT
Renewable energy resources are getting priorities in the whole world in order to
provide a sustainable power production and safe world to the future generation. Solar
energy is rapidly gaining the focus as an important means of expanding renewable energy
uses. Solar trackers are the most appropriate and proven technology to increase the
efficiency of solar panels through keeping the panels aligned with suns position. A
microcontroller based design methodology of an automatic solar tracker is presented in
this paper. The unit controls the movement of solar panel always aligned towards the
direction of the sun, due to this maximum thermal energy would be culminated from solar
panel. Sun always moves from east to west direction independent of weather condition, so
with this concept without using sensors movement of the solar panel from east to west
direction is done with the help of programme loaded into the microcontroller. This
prototype is designed for single axis as well as for double axis to solve solstice problem.
From hardware testing we come to know that solar tracking system tracks the sun
precisely and provides more power at the output as compared to that static solar panel.
Keywords: Solar panel, solar tracking, microcontroller, stepper motor, liquid crystal
display.
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2. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
I. INTRODUCTION
Energy is essential factor for the development of any nation. Most of the energy
production depends on fossil fuels. The resources of the fossil fuels are limited, so that
there is growing demand for energy from renewable resources like solar, geothermal and
ocean tidal wave. Among all renewable systems photovoltaic system is the one which has
great chance to replace the conventional energy resources. Solar panel directly converts
solar radiation into electrical energy. Solar panel is mainly made from semiconductor
materials. To enhance the performance of solar panel the only way is to increase the
intensity of light falling on it. Solar tracker is the best technology to increase the
efficiency of solar panel by keeping panel aligned with the suns position. In this paper a
microcontroller based simple and easily programmed automatic solar tracker is presented.
II. TECHNOLOGY TO ENHANCE POWER OUTPUT FROM SOLAR PANEL
In order to increase the efficiency of photovoltaic system there are three methods.
First is increasing the efficiency of solar cell, second is maximizing the power output and
third is employing a tracking system. Improvement of solar cell efficiency is an ongoing
research work and people throughout the world are actively doing research on this.
Maximum power point tracking is the process to maximize the output power from solar
panel by keeping the solar panels operation on the knee point of photovoltaic
characteristics. A number of maximum power point tracking algorithms have been
developed and employed around the world [1]. At particular time, maximum power can
be received from a stationary array of solar panel in case of maximum power point
tracking technology. However, it cannot increase the power generation when the sun is
not aligned with the system. Automatic solar tracker increases the efficiency of the solar
panel by keeping the solar panel aligned with the rotating sun. Solar tracking is a
basically electromechanical system to track the suns position that increases power output
of solar panel 30% to 60% than the stationary system [2]. A few design methodology of
solar tracking system has been proposed in recent days [3]-[4]. Maximum rays from the
sun reach on the earth’s surface through interaction of clouds, dusts and water. These rays
are called as diffused rays which reduces the output of solar cell. If these rays reflected on
the panel through the reflectors it will increase the overall output of the panel [5].
III. PHOTOVOLTAIC TECHNOLOGY
Solar energy is most abundant and convenient source of renewable energy.
Photovoltaic cells are the basic of solar system. In the word photovoltaic “photo” means
light and “voltaic” means producing electricity. Therefore the photovoltaic process is
producing electricity directly from sunlight. The output power of a photovoltaic cell
depends on the amount of light projected on the cell. The output power also depends on
the time of day, season, panel position and orientation.
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3. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
IV. AUTOMATIC SOLAR TRACKING SYSTEM
The sun moves across the sky during the day, it is advantageous to have the solar
panels track the location of the sun such that the panels are always perpendicular with the
position of the sun. But available solar trackers in the market are much more costly to
integrate with solar panel system [6]. Solar tracking presented in this paper can provide an
effective solution to such problem. The major components those are used in the system are
given below.
. Microcontroller
. Stepper motor
. L293D
.Liquid crystal display
Fig. 1 shows the schematic diagram of automatic solar power tracking system.
Fig.1 Schematic of solar tracker circuitry
A. Microcontroller
The PIC18F452 microcontroller has been used in the system. Microcontroller is the heart
of overall system. PIC 18F452 has some features such as analog comparator(AC), analog to
digital converter (ADC), universal synchronous asynchronous receiver transmitter (USART),
timers and parallel slave port (PSP).
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4. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
B. Stepper motor
Stepper motors are commonly used in precision positioning control applications. Five
characteristics of stepper motor have been considered while choosing stepper motor for solar
tracker. Stepper motor is brushless, load independent, has open loop positioning capability,
good holding torque and excellent response characteristics. The stepper motor that has been
used in the system has the specifications of 4.4volts, 4 resistance, 1.8º per step, 2 phases,
bipolar.
C. L293D
L293D is quadruple high-current half-H driver. All inputs are TTL compatible. Each
output is a complete totem-pole drive circuit with a Darlington transistor sink and a pseudo-
Darlington source. The L293D has some features such as wide supply voltage range 4.5V to
36V, separate input logic supply, thermal shutdown, high noise immunity inputs, output
current 600mA per channel, peak output current 1.2mA per channel and output clamp diodes
for inductive transient suppression.
D. Liquid crystal display
16X2 character Liquid crystal display is used in this system to display solar panel voltage
and number of cycles completed.
V. OPERATION OF THE SOLAR TRACKER
Solar tracker provides three ways of operation and control mechanism through the
programme written in the microcontroller. The three ways of operation includes normal day
light condition, bad weather condition and bidirectional rotation. Whether there is normal day
light or bad weather sun always present in the sky. With this programme loaded into the
microcontroller to move the panel from east to west direction automatically. Once the day of
24 hours completed panel brought to initial position to start the new day.
The entire day is divided into 24x6=144 parts of 10 minute each. The day light is
assumed to be present for 10 hours that is 60 parts of 10 minutes. Stepper motor has
resolution of 1.8ºper step. The worm gear ratio that has been used is 30:1. With this the
number of steps required by the stepper motor to move the panel through 2.4º is 40. With
beginning of the daylight from a reference point the system starts counting the stepping
cycles each of 40 steps. Three counters used counter1 for day light, counter2 for whole day
and conuter3 for season correction. After every one month the light emitting diode will
turned ON to indicate there is need to do correction to solve elevation problem. For this
purpose a separate mechanism of fine pitch of lead screw is used for compensating the
elevation of the sun. Once the counter1 reaches 60 counts there will be no further movement
of the stepper motor. But the counting of the cycles continues up to 144 in counter2. This
completes the day of 24 hours. The numbers of days are calculated in counter3. As number
of days is not equal to 365 then panel is brought to initial position by counting 60 cycles
backward. Then start the new day. But whenever number of days is equal to 365 then
resetting of all counters is required. A 6volt lead acid rechargeable cell is used as storage
element for the motor drive as well as the power supply for the other circuits. Operational
flow of the solar tracker is given in fig.2
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5. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
Fig.2 Operational flow chart of solar tracker
VI. HARDWARE TESTING OF SOLAR PANEL
Table I shows the data of voltage, current and power received from solar tracking
system and static solar panel for a day. Fig. 3 shows the comparison of electric power
characteristic curves from solar tracking system and static solar panel. It shows that solar
tracking system is able to receive more Sunlight and consequently generate more power as
compared to static solar panel.
TABLE I
Observations of solar panel during hardware testing
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6. International Journal of Electrical Engineering and Technology (IJEET), ISSN 0976 –
6545(Print), ISSN 0976 – 6553(Online) Volume 4, Issue 1, January- February (2013), © IAEME
Fig. 3 Electric Power vs. Hours characteristic curve
VII. CONCLUSION
The proposed sun tracker automatically tracks the sun capturing maximum solar
power with help of microcontroller. The system tracks the sun both in normal and bad
weather condition. The tracker can initialize the starting position itself which reduce the need
of any more photo resistor. Summer solstice and winter solstice problem is solved manually
by tilting the panel with the help of fine screw arrangement.
REFERENCES
[1] C. Hua and C. Shen (1998) Comparative study of peak power tracking techniques for
solar storage system’’, Applied Power Electronics Conference and Exposition, vol. 2, pp.
679-685.
[2] A. K. Saxena and V. Dutta (1990), “A versatile microprocessor based controller for solar
tracking’’, Photovoltaic Specialists Conference, vol. 2, pp. 1105-1109.
[3] B. Koyuncu and K. Balasubramanian (1991), “A microprocessor controlled automatic sun
tracker’’, IEEE Transactions on Consumer Electronics, vol. 37, no. 4, pp. 913-917.
[4] Md. Tanvir Arafat Khan, S. M. Shahrear Tanzil, Rifat Rahman, S M Shafiul Alam (2010)
“Design and construction of an automatic solar tracking system”, international conference on
electrical and computer engineering, Dhaka, Bangladesh.
[5] R. U. Rahman, D. I. Ahmed, M. A. Fahmi, T. Tasnuva M. F. Khan (2009),
“Performance Enhancement of PV solar system by diffused refection”, Intl. Conf. on the
Developments in Renewable Energy Technology, PP. 96-99.
[6] WATTSON™ SOLAR TRACKER RETAIL PRICE AND DATA SHEET.
[Online].Available: http://www.wattson.com/prices.html
[7] “Microcontroller” datasheet. [Online] Available:
http://www.microchip.com/downloads/en/devicedoc/ 39564c.pdf.
[8] “L293D” datasheet. [Online]. Available: http://idmax.free.fr/Aide/stepper/i293.pdf
[9] “LM317” datasheet. [Online]. Available:
http://www.ee.baffalo.edu/courses/elab/LM117.pdf.
[10] Neeraj Tiwari, D. Bhagwan Das and Prabal Pratap Singh, “Design, Development And
Hardware Realization Of X-Beebased Single Axis Solar Tracking System” International
Journal of Electrical Engineering & Technology (IJEET), Volume 3, Issue 3, 2012,
pp. 8 - 20, Published by IAEME
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