1. 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.
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2. INDEX:
S.NO
LIST OF TOPICS
P.NO
1.
INTRODUCTION
3
2.
BLOCK DIAGRAM
4
3.
LIST OF COMPONENTS
5
4.
INTERFACING OF COMPONENTS WITH
MICROCONTROLLER
12
5.
WORKING OF SOLAR TRACKER
13
6.
ADVANTAGES AND DISADVANTAGES
14
7.
CONCLUSION
16
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3. INTRODUCTION:
Commercial made solar trackers are a nice addition to any solar panel array.
They help increase the time that panels directly face the sun and allow them to produce their
maximum power. Unfortunately they can be expensive to buy. We decided to make our own
solar tracker to see if we could reduce the cost. We did not want to reinvent the wheel but
wanted to make it more affordable. We started out small and came up with the idea of solar
tracking using time instead of using a device that would sense where the sun is and move
the panels toward it. The objective of this project is to control the position of a solar panel in
accordance with the motion of sun. Brief Methodology: This project is designed with solar
panels, RTC, Microcontroller, Stepper Motor and its driving circuit. In this project RTC is used
to find or the location of Sun. It’s a open loop system.
Renewable energy is rapidly gaining importance as an energy resource as
fossil fuel prices fluctuate. At the educational level, it is therefore critical for engineering and
technology students to have an understanding and appreciation of the technologies
associated with renewable energy. One of the most popular renewable energy sources is
solar energy. Many researches were conducted to develop some methods to increase the
efficiency of Photo Voltaic systems (solar panels). One such method is to employ a solar
panel tracking system. This project deals with a RTC based solar panel tracking system.
Solar tracking enables more energy to be generated because the solar panel is always able
to maintain a perpendicular profile to the sun’s rays. Development of solar panel tracking
systems has been ongoing for several years now. As 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 to the solar energy radiated by the sun. This will tend to
maximize the amount of power absorbed by PV systems. It has been estimated that the use
of a tracking system, over a fixed system, can increase the power output by 30% - 60%. The
increase is significant enough to make tracking a viable preposition despite of the
enhancement in system cost. It is possible to align the tracking heliostat normal to sun using
electronic control by a micro controller. Design requirements are:
1) during the time that the sun is up, the system must follow the sun’s position inthe sky.
2) This must be done with an active control, timed movements are useful. It should be totally
automatic and simple to operate. The operator interference should be minimal and restricted
to only when it is actually required
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4. BLOCK DIAGRAM:
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5. LIST OF COMPONENTS:
 Power supply
 Microcontroller(AT89C51)
 Solar panel
 DC motor
 LCD(Liquid crystal Display)
 RTC(Real Time Clock-DS1307)
 L293D Driver
 keypad
POWER SUPPLY:
In this project power supplies with +5V & -5V option normally +5V is enough for total
circuit. Another supply is used in case of OP amp circuit .Transformer primary side has
230/50HZ AC voltage whereas at the secondary winding the voltage is step downed to
12/50hz and this voltage is rectified using two full wave rectifiers .The rectified output is given
to a filter circuit to filter the unwanted ac in the signal After that the output is again applied to
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6. a regulator LM7805(to provide +5v) regulator. WhereasLM7805 is for providing 5V
regulation.
CIRCUIT FEATURES:
Brief description of operation: Gives out well regulated +5V output, output current capability
of 1A
Circuit complexity: Very simple and easy to build
Circuit performance: Very stable +5V output voltage, reliable operation
Power supply voltage: 230V AC
Power supply current: 1A
MICROCONTROLLER:(AT89C51)
AT89C51 MICROCONTROLLER
FEATURES
89C51 based architecture
8
-Kbytes of on-chip Reprogrammable Flash Memory
 128 x 8 RAM
 Two 16 Timer/Counters
-bit
 Full duplex serial channel
 Boolean processor
 Four 8 I/O ports, 32 I/O lines
-bit
 Memory addressing capability
– 64K ROM and 64K RAM
 Power save modes:
– Idle and power-down
 Six interrupt sources
 Most instructions execute in 0.3 us
 CMOS and TTL compatible
Maximum speed: 40 MHz @ Vcc = 5V
 Industrial temperature available
 Packages available:
– 40-pin DIP
– 44-pin PLCC
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7. – 44-pin PQFP
SOLAR PANEL:
Photovoltaic energy is the conversion of sunlight into electricity. A photovoltaic cell,
commonly called a solar cell or PV, is the technology used to convert solar energy directly
into electrical power. A photovoltaic cell is a non mechanical device usually made from silicon
alloy The photovoltaic cell is the basic building block of a photovoltaic system. Individual
cells can vary in size from about 0.5 inches to about 4 inches across. However, one cell only
produces 1 or 2 watts, which isn't enough power for most applications.
The performance of a photovoltaic array is dependent upon the sunlight .Climatic conditions
(eg., clouds, fog) have a significant effect on the amount of solar energy received by a
photovoltaic array and, in turn, its performance. Most current technology photovoltaic
modules are about 10% efficient in converting solar radiation. Further research is being
conducted to raise this efficiency to 20%.
BRUSHLESS DC GEAR MOTOR :
Conventional DC motors use a stationary magnet with a rotating armature
combining the commutation segments and brushes to provide automatic commutation.
In comparison, the brushless DC motor is a reversed design: the permanent
magnet is rotating whereas the windings are part of the stator and can be energized without
requiring a commutator-and-brush system.
SPECIFICATION:
 INPUT VOLTAGE-15V
 INPUT CURRENT- 0.6A
 R.P.M -10:1
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8. Fig. Brushless Dc Motor
LCD (LIQUID CRYSTAL DISPLAY) :
The Liquid Crystal Display (LCD) is a low power device (microwatts). Now a
days in most applications LCDs are using rather using of LED displays because of its
specifications like low power consumption, ability to display numbers and special characters
which are difficult to display with other displaying circuits and easy to program. An LCD
requires an external or internal light source. Temperature range of LCD is 0ºC to 60ºC and
lifetime is an area of concern, because LCDs can chemically degrade these are
manufactured with liquid crystal material (normally organic for LCDs) that will flow like a liquid
but whose molecular structure has some properties normally associated with solids .
FIELD EFFECT LCD:
Field-effect LCDs are normally used in such applications where source of energy is a
prime factor (e.g., watches, portable instrumentation etc.).They absorb considerably less
power than the light-scattering type. However, the cost for field-effect units is typically higher,
and their height is limited to 2 inches. On the other hand, light-scattering units are available
up to 8 inches in height. Field-effect LCD is used in the project for displaying the appropriate
information
Fig.Liquid Crystal Display
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9. DS 1307(RTC)
Real-Time Clock (RTC) Counts Seconds, Minutes, Hours, Date of the Month,
Month, Day of the Week, and Year with Leap-Year
Fig.DS1307 pin and Pin configuration
The DS1307 serial alarm real-time clock provides a full binary coded decimal
(BCD) clock calendar that is accessed by a simple serial interface. The clock/calendar
provides seconds, minutes, hours, day, date, month, and year information. The end of the
month date is automatically adjusted for months with fewer than 31 days, including
corrections for leap year. The clock operates in either the 24-hour or 12-hour format with
AM/PM indicator. In addition, 96 bytes of NV RAM are provided for data storage. The
DS1307 will maintain the time and date, provided the oscillator is enabled, as long as at least
one supply is at a valid level
An interface logic power-supply input pin (VCCIF) allows the DS1307 to drive SDA and SCL
pins to a level that is compatible with the interface logic. This allows an easy interface to 3V
logic in mixed supply systems.
The DS1307 offers dual-power supplies as well as a battery input pin. The dual power
supplies support a programmable trickle charge circuit that allows a rechargeable energy
source (such as a super cap or rechargeable battery) to be used for a backup supply. The
VBAT pin allows the device to be backed up by a non-rechargeable battery. The DS1307 is
fully operational from 2.0V to 5.5V.
Two programmable time-of-day alarms are provided by the DS1307. Each alarm can
generate an interrupt on a programmable combination of seconds, minutes, hours, and day.
“Don’t care” states can be inserted into one or more fields if it is desired for them to be
ignored for the alarm condition.
The time-of-day alarms can be programmed to assert two different interrupt
outputs or to assert one common interrupt output. Both interrupt outputs operate when the
device is powered by VCC1, VCC2, or VBAT.
The DS1307 supports a direct interface to SPI serial data ports or standard 3-wire interface.
A straightforward address and data format is implemented in which data transfers can occur
1 byte at a time or in multiple-byte-burst mode.
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10. L293D DRIVER:
The L293D is a monolithic integrated high voltage, high current four channel driver
designed to accept standard DTL or TTL logic levels and drive inductive loads (such as
relays solenoids, DC and stepping motors) and switching power transistors. To simplify use
as two bridges is pair of channels is equipped with an enable input. A separate supply input
is provided form the logic, allowing operational at a low voltage and internal clamp diodes are
included. This device is suitable for use in switching applications at frequencies up to 5 KHz.
The L293D is assembled in a 16 lead plastic package which has 4 center pins connected
together and used for heat sinking.
Fig.L293D pin configuration
FEATURES:
 600ma. output current capability perchannel
 1.2a pe ak o utput current (nonrepetitive) per channel
 enable facility
 overtemperature protection
 logical ”0” input voltage up to 15v
 internal clamps diodes
KEYPAD:
Keypads are a part of HMI or Human Machine Interface and play really important
role in a small embedded system where human interaction or human input is needed. Matrix
keypads are well known for their simple architecture and ease of interfacingwith any
microcontroller.
Scanning a matrix keypad:
There are many methods depending on how the keypadis connected with the controller,
but the basic logic is same. The columns as i/p and rows making them o/p, this whole
procedure of reading the keyboard is called scanning.
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11. Fig. Matrix Keypad
CRYSTAL OSCILLATOR:
crystal oscillator is an electronic circuit that produces electrical oscillations at a
particular designed frequency determined by the physical characteristics of one or more
crystals, generally of quartz, positioned in the circuit feedback loop. A piezoelectric effect
causes a crystal such as quartz to vibrate and resonate at a particular frequency. The quartz
crystal naturally oscillates at a particular frequency, its fundamental frequency that can be
hundreds of megahertz. The crystal oscillator is generally used in various forms such as a
frequency generator, a frequency modulator and a frequency converter.
Fig. CRYSTAL OSCILLATOR
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12. INTERFACING OF COMPONENTS WITH MICROCONTROLLER AT89C51:
Interfacing Lcd With Microcontroller
Fig. Interfacing of DS1307 with
Fig. Interfacing of L293D with DC Motor
microcontroller
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13. WORKING OF SOLAR TRACKING SYSTEM:
The system contains two modules, one is tracking and the other is controlling
module. Tracking module which will take angular rotation with the help of DC gear motor in
synchronous with the starting position of the sun. As sun rises from East, it will also take the
angle according to the angle of raising sun. So it will continuously track the sun till the sun
sets in the West.
Initially when the supply from the power kit was drawn and given to all the components
of the control circuit and keyboard. When the power supply is switched ON the panel comes
to the original position and by the keypad switches the clock time in the LCD screen can be
setted by the keypad switches. K1, K2 and K3 are the switches of keypad. K1 represents
Increment switch, K2 represents Decrement switch and K3 represents Enable switch. Initially
the panel stands at reference position 8:00AM and according to the setting time the panel
rotates with the help of brushless DC Gear Motor.
Module is designed with efficient Microcontroller from ATMEL 89C51 which helps to
drive the tracking module at different instants. The keypad switches was connected to the
microcontroller through latch to the port2(Pins 2.6, 2.7,2.8) and microcontroller was
connected to the LCD screen through the pins(P1.4 to P1.7) and the LCD displays the preset
time.
DS1307 is the RTC(Real Time Clock) used to produce clock pulses through
microcontroller which connects the LCD display, displays the time.
L293D driver was connected to the DC Motor, microcontroller and 9V battery. The
pulses that was produced by the microcontroller helps to connect the DC supply to the DC
brushless motor.
The DC brushless motor was mounted on a separate stand and connected to a shaft
which rotates the solar panel given from the microcontroller based upon this gear motor
operates.
When the supply was given to the dc gear motor, according to the setting from keypad,
the solar panel reaches the set state from the initial position with one degree as one second
and after reaching the set position it covers every degree by one degree.
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
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14. beginning of the daylight from a reference point the system starts counting the stepping
cycles each of 40 steps.
ADVANTAGES:
1. Solar power is pollution free during use. Production end wastes and emissions are
manageable using existing pollution controls. End-of-use recycling technologies are under
development.
2. Facilities can operate with little maintenance after initial setup.
3. Solar electric generation is economically superior where grid connection or fuel transport is
difficult, costly or impossible.
4. When grid-connected, solar electric generation can displace the highest cost electricity
during times of peak demand can reduce grid loading.
5. Grid-connected solar electricity can be used locally thus reducing transmission/distribution
losses.
6. Once the initial capital cost of building a solar power plant has been spent, operating costs
are extremely low compared to existing power technologies.
7. The power obtained by solar tracking is almost constant over a period of time when
compared with the output obtained by a panel without tracking.
DISADVANTAGES:
1. Solar electricity is almost more expensive than electricity generated by other sources.
2. Solar electricity is not available at night and is less available in cloudy weather conditions.
Therefore, a storage or complimentary power system is required.
3. Limited power density.
4. Solar cells produce DC which must be converted to ACwhen used in currently existing
distribution grids
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15. Fig. Overview Of Simple Solar Tracker
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16. CONCLUSION:
In recent years, the generation of electricity using solar technology has seen a
tremendous growth, in particular because of the economic considerations and smooth
operation of the solar panels. Even though the initial costs are high, but operation costs and
maintenance costs are low. Solar tracking system today offer an innovative method to track
the solar insolation and provide economic compatibility of the generation of electric power
where grid connections are difficult to setup and costly.
Here the tracking system is based on microcontroller with effective systematic operation and
the solar panel is rotated by the dc gear motor effectively.
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