embedded solar tracking instrumentation system
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Abstract—This paper describes the embedded solar tracking
instrumentation system by using Atmega32 microcontroller. The
system consists of Light Dependent Resistor (LDR) sensor, DC
motor and Xbee wireless system. Atmega32 microcontroller is the
main component for controlling the system. The solar system will
track the location of the sun to ensure the solar panel is always
perpendicular with the sun therefore optimizing power output.
The operation of the system on sunny and bad weather condition
has been presented in this paper. The solar tracking prototype
has been stated for future works.
Index Terms–Embedded, Microcontroller, Wireless, Solar
panel, Solar tracking
I. INTRODUCTION
he global warming crisis , which is mainly caused by
carbon emission is an issue of alarming concern.
Immediate, effective and practical actions to eradicate the
problem should be taken before it worsens. The emission of
carbon as a by-product of electric generation from fossil fuels
impacts lives and the Mother Nature. Renewable energy such
as solar energy provides a sustainable, safer and much
healthier power production, in return safeguarding the earth
from the dangers of pollution. To date, solar energy is the best
way to replace fossil fuels as the main source for generating
electricity.
Solar energy uses sun rays that is an unlimited source and
available for a long term with zero pollution by-product
compared to fossil fuels [1-5]. Besides, the solar energy source
is free while the price of fossil fuels had tripled for the last 15
years [3].
The limitation on existing solar energy system is the system
is not efficient as it generates low power output and demands
high cost. This can be solved by developing an embedded
system based on Atmega32 microcontroller and by adding
Xbee wireless system for collecting and monitoring data.
Nowadays, Atmega32 microcontroller and Xbee wireless
system are widely used in the development of an embedded
system in many areas. It is because of the reasonable cost,
simplicity and ability to connect with a large number of
devices [6]. Both Atmega32 and Xbee are easy to install and
can be used in any situation.
This work was supported by the Ministry of Higher Education (MOHE)
and UniversitiTeknologi Malaysia.
II. SOLAR ENERGY TECHNOLOGY
The enhancement of solar energy system has grown from
fixed mounted to tracking instrumentation solar panel system
and flat to parabolic dish solar panel. The early solar energy
technology is based on fixed mounted solar system. The
tracking system is added in order to improve the efficiency of
the existing system. The purpose of the tracking system is to
overcome the limitation of fixed solar panel mountings
system.
The shading effect is considered in tracking the location of
the sun. The sunlight was diffused through the interaction of
clouds and dusts [1] [7]. The purpose of parabolic dish solar
system is to ensure the sunlight can be focused at one point
and it can increase the efficiency of the solar energy system.
The improvement of the solar energy system by implementing
the tracking system and parabolic dish will gain maximum
power output due to the alignment of solar panels towards the
sun.
The most important aspect in the tracking instrumentation
system is to track the location of the sun. The location of the
sun depends on the latitude of the site and according to the
times of the years [1]. Based on the location of the sun as
desired orientation, the tracking device will trigger the motor
to operate the solar energy system. The tracking device is used
in order to ensure the panel is aligned with the sun. Hence, the
maximum output power gain can be achieved.
Solar tracking instrumentation is a closed-loop function
system. A closed-loop function system is known as feedback
system. Feedback system is needed to ensure the solar panel
always perpendicular with the sun. Fig. 1 shows the block
diagram of solar tracking system.
Location of the sun is set as desired input of the system.
The sensor is used as the tracking system. The subject of
orientation for the system is a condition of the sunlight. It can
be either east or west and north or south. Measuring device
that used as feedback system is the movement of the motor.
Finally, the sun is perpendicular with the solar panel.
Fig. 1: Block diagram of the solar tracking instrumentation system
Embedded Solar Tracking Instrumentation
System A.H. Yamin, M. N. Ibrahim, M. Idroas and A.R. Zin
UniversitiTeknologi Malaysia
81310 UTM Johor Bahru, Malaysia
T
978-1-4673-5074-7/13/$31.00 ©2013 IEEE
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO2013), Langkawi, Malaysia. 3-4 June2013
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III. SOLAR TRACKING INSTRUMENTATION SYSTEM
The overall solar tracking system is shown in Fig. 2. The
main control system for the solar tracking system is Atmega32
microcontroller. By implementing Atmega32 microcontroller
in this project, the microcontroller is used to control the
process flow and data transfer and stored the data for further
use.
The Light Dependent Resistor (LDR) sensor is used and it
was attached to the dish parabolic concentrator to ensure the
system is always perpendicular with the sun. The sensor will
detect the sunlight and transmit the signal to Atmega32
microcontroller. Then, the microcontroller will trigger the
motor to move accordingly. The detection of the sun is based
on the signal received from the sensor to make sure the panel
is always perpendicular with the sun.
At the same time, the data received from the sensor will be
stored in Atmega32 microcontroller. The information stored in
Atmega32 microcontroller will then be sent to the computer
by using Xbee wireless system to be analyzed and saved.
The sunlight will strike the surface of the dish parabolic
reflector. Then, the sunlight is reflected to the solar panel that
is placed at the focal length of the dish parabolic system. The
light energy will be converted into electrical energy when the
light strikes the solar panel. The output from the solar system
is Direct Current (DC) which can be stored to the battery or
converted to the Alternating Current (AC).
The circuit for all solar energy system is designed by using
Proteus software. The circuit is separately designed and
consists of:
• Atmega32 microcontroller
• Light dependent resistor (LDR) sensor
• DC motor
• XBEE wireless
Fig. 2: Overall solar tracking system
A. Atmega32 microcontroller
Atmega32 microcontroller is the main part of the system.
Atmega32 microcontroller is a high performance with low
power microcontroller. The operating voltage for Atmega32
microcontroller is 5V. The speed grades of Atmega32
microcontroller is up to 16MHz [8]. The Atmega32
microcontroller is used for comparing the external comparator
output, controlling motor movement for the dual-axis system
and to control the Xbee wireless system. Fig. 3 shows the
photograph of Atmega32 microcontroller.
Fig. 3: Atemega32 microcontroller
Atmega32 microcontroller has 40 pins and every pin has
their own functions. Some of the features used in this project
are programmable I/O line, 8-channel 10-bit analog to digital
converter (ADC) at PORTA and universal synchronous
asynchronous receiver transmitter at PORTD (Pin 14 and Pin
15). Fig. 4 shows the pin configuration for Atmega32
microcontroller.
Fig. 4: Atmega32 layout
B. Light Independent Resistor (LDR) sensor
By implementing the tracking system in solar energy
system, the location of the sun can be determined. The system
tracks the sun based on light intensity of the sunlight. In this
project, light dependent resistor (LDR) is used as the
sensoring device to detect the sunlight. Five LDR sensors are
installed in the system.
One of the sensors is used as a switch for the system. When
this sensor detects sunlight, the system will be enabled. Two
other sensors are used to detect the sunlight either north or
south along azimuth motion of the system while another two
sensors are used to detect the sunlight either east or west along
altitude motion of the system.
In this project, three comparators have been installed. Each
comparator is used to compare the value of two sensors. The
value of the sensor is based on the presence of the sunlight.
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO2013), Langkawi, Malaysia. 3-4 June2013
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The comparator is connected to Atmega32 microcontroller as
the input for the tracking system.
Furthermore, four LEDs are also used in the system as the
indicator for the movement of the motor. For example, two
sensors are placed at left and right of the parabolic dish. When
the system detects the presence of the sunlight, all the LEDs
are switched on. When one side of the sensor is gain more
sunlight, one of the LED will be switched on and the DC
motor will move anti-clockwise and vice versa. Fig. 5 shows
the connection of the sensor.
Fig. 5: Connection of the sensor
C. DC Motor
Two DC motor are required in the solar tracking
instrumentation system. The first motor is used to move along
azimuth motion which is either north or south. Another motor
is used to move along altitude motion which is either east or
west.
Motor driver is required to drive the motor. The motor
driver is connected between Atmega32 microcontroller and
DC motor. The 12V DC supply does not give enough torque
to move the motor. The power amplifier circuit is needed in
order to give enough torque to move the motor. So, Darlington
pair circuit is placed in between the motor driver and DC
motor [9]. Fig. 6 shows the connection between Atmega32,
motor driver and DC motor.
Fig. 6: connection between Atmega32, motor driver and DC motor
D. XBEE Wireless System
Most developers of solar tracking system are not really
concerned on collecting the data. There is not much work done
on applying wireless network system to collect the data real-
time [10] [6]. The data received from the solar tracking system
are monitored manually at site. Sometimes, it is hard to collect
the data during a bad weather.
In this project, Xbee wireless system will be used to collect
the data based on real-time. These days, Xbee wireless system
is widely used for data transferring. By using XBEE wireless
system, data monitoring becomes easier. Besides, it is cheap
and compatible to use in most situation. Fig. 7 shows the Xbee
wireless system module.
Fig. 7: Xbee wireless module
The Xbee wireless system has low data transfer rate which
is 250kb/s and it has low power consumption [11-14]. The
input voltage to the Xbee wireless system is 3.3V. The
distance range for indoor is up to 30 meter while for outdoor,
it is up to 100 meter [10]. The Xbee wireless system is based
on 802.15.4 IEEE standard protocols [12]. Fig. 8 shows the
connection of Xbee wireless system.
Fig. 8: Connection of Xbee wireless system
IV. OPERATION OF SOLAR TRACKING SYSTEM
Basically, the sensors can detect the exact location of the
sun with the presence of sunlight. However, the weather
conditions are not sunny all the time. Therefore, the operation
of solar tracking system should include the bad weather
condition too such as cloudy day and rainy day. The operation
is based on presence of the sun throughout the year. The
operational flow chart is shown in Fig. 9. This project
provides two ways of operation and control mechanism which
are:
• Normal sunny condition
• Bad weather condition
The presence of the sun can be identified by knowing the
latitude and longitude of the site. The latitude and longitude of
Malaysia is +3.16 (3º09º36º N) and +101.71 (101º42º36º E)
[15]. So, the sunrise is about 7 a.m. while the dawn about 7
p.m. In this project, the system will be started an hour after the
sunrise which is 8 a.m. The system will be stopped an hour
before dawn which is 6 p.m. Fig. 10 shows the time of sunrise
and dawn in Malaysia.
A. Normal Sunny Condition
Four sensors are used to detect the presence of the sunlight.
The output voltages from two sensors that represent east/west
and north/south are compared. The east sensor is compared
with the west sensor and the north sensor is compared to the
south sensor. Based on the result obtained from the sensor, the
solar panel will track the sun.
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO2013), Langkawi, Malaysia. 3-4 June2013
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B. Bad Weather Condition
On bad weather day, the sensor cannot detect the presence
of the sunlight because of the interaction of clouds and dusts.
The sunlight that strikes the system will lessen and insufficient
voltages will be received by the sensor. It can be difficult to
the sensor to determine the exact location of the sun. The
problem can be solved by implementing the algorithm for the
movement of the solar panel. The rotation of the earth towards
the sun is 360º in 24 hours. Every hour, the earth rotate about
(360º/24=) 15º. So, to collect data every 15 minutes, the
rotation of the earth towards the sun is about 3.75º [7].
Fig. 9: Flow chart of the solar tracking system
Fig. 10: Sunrise and dawn in Malaysia [15]
V. PRELIMINARY RESULT
The simulation test has been conducted to verify the
interaction between light sensor and motor. Fig. 11 shows the
circuit of the interaction between light sensor and motor. This
circuit consists of two light sensors to detect the light, two
motors and two LED as indicator. The motor rotates either
clockwise or anti-clockwise when the sensors detect the
presence of the light.
Fig. 11: Interaction between light sensor and motor circuit
VI. DESIGN OF SOLAR TRACKING SYSTEM
The development of the overall solar tracking system has
two stages and it is done separately. The first stage is
developing a software system that focuses on the operation of
the solar embedded system. Meanwhile, the second stage is
developing a hardware system which consists of developing
on the prototype of solar tracking instrumentation system. Fig.
12 shows the prototype of solar tracking instrumentation
system. The prototype is built using polyvinyl chloride (PVC)
material because of low cost, flexibility and durability for
higher temperature. The idea of prototype platform is based on
tripod due to stability of the system. Roller is installed to
move easily from one location to others.
Fig. 12: Prototype of solar tracking instrumentation system.
2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO2013), Langkawi, Malaysia. 3-4 June2013
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The construction of the prototype will be done based on the
operation of the solar that had been developed on software
stage. The design of the prototype consists of four sensors that
are placed on the north, south, east and west of the parabolic
dish. The installation of the sensor is sufficient enough to
detect the exact location of the sun and to ensure the solar
panel is always facing towards the sun.
The system used parabolic dish to reflect the sunlight. Small
solar panel is placed at the focal length of the parabolic dish.
As a result, the sunlight will be reflected and focused on the
solar panel hence maximizing the power output gained. Fig.
13 shows parabolic dish reflector that can be used for
developing the prototype of solar tracking system.
Fig. 13: Parabolic dish reflector
VII. CONCLUSIONS
The paper has presented a method of embedded solar
tracking instrumentation system by implementing Atmega32
microcontroller. A solution to maximize the solar panel output
is done by positioning the solar panel towards the sun to gain
maximum light intensity. A method for tracking the sun on
sunny and bad weather condition is also discussed in this
paper. The systems also provide more convenient ways on
data collection by implementing Xbee wireless system.
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