A Solar Energy System S ystem by Effective Sun Tracking System SANTHIRAM ENGINEERING COLLEGE NANDYAL_518501 KURNOOL (DT)
Presented by T.GURUBHASKAR
M.Jithendra
[email protected]
[email protected]
3/4.E.E.E
3/4 E.E.E
Ph. no: 9491417285
Ph.no:9700717030
the solar panel and grasping the maximum power
ABSTRACT
Electric power is the major aspect for a human being. Without electric power there is no world.
from the sun by rotating the solar panel according to the sun rays direction with respect to time.
Electric power can be generated by many ways like
In present situation everyone is facing the
coal, water, nuclear etc. Generation of power from
problem with power cuts which is creating very
non-conventional energy sources improves the
much trouble to the people. So, to solve this
system efficiency, reliability and reduces pollution.
problem we have a solution that is sun. Yes by
One of such non-conventional energy source is
using sun radiation we can get power i.e., the solar
SOLAR ENERGY which is a complete pollution
energy using which we generate the power. All we
free. A solar panel is a device that converts the
are know that there are so many renewable energy
energy of sunlight directly into electricity by the
sources like solar, wind, geothermal etc. but solar
photovoltaic
energy system is very simple and easy to
effect.
In
our
project
we
are
generating power from sun by effective sun
implement. But the main drawback of the solar
tracking system means we utilize the maximum
system is it is very poor efficient system. By using
radiation from sun by following the sun¶s elevation
this project we are going to improve the efficiency
throughout the day using solar plates. A battery is
of solar system.
connected to the solar plant to store the generated electric power. This power is utilized for the
In which solar panel will turn according to
domestic applications. Solar panel is connected to
the sun rotation with predefined angle. So by using
Microcontroller through AT89S52 for controlling
DC motor we are going to turn the panel according
panel such that it follows sun direction.
to the time. Whenever the radiation of the sun falls on the solar panel it grasps the radiation and stores
I. INTRODUCTION
Most of the electricity in India comes from
in it and it will send the message to the controller
fossil-fuels like coal, oil and natural gas. Today the
about
demand of electricity in India is increasing and is
Microcontroller will receive this information and
already
of
display on LCD. As the time passes the panel
electricity where as the reserves of the fossil-fuel
rotates with the help of motor. Here RTC (Real
are depleting every day. We can feel this fact from
Time Clock) is used to give the exact time intervals
the electricity-cuts during summer. Luckily Sun
to the controller.
more
than
the
production
throws so much energy over India, that if we can trap few minutes of solar energy falling over India we can provide India with electricity for whole year. Most parts of India get 7 KWH/ sq.-meter of energy per day averaged over a year.
maximum
power
from
solar
power
which
is
stored
in
it.
Solar Panels are a form of active solar power, a term that describes how solar panels make use of the sun's energy: solar panels harvest sunlight and actively convert it to electricity. Solar Cells, or photovoltaic cells, are arranged in a grid-
The main aim of this project is to generate the
its
panel
by
continuously tracking the sun rays.
like pattern on the surface of the solar panel. Solar panels are typically constructed with crystalline silicon, which is used in other industries (such as
The purpose of the project is to implement a system
the
microprocessor
industry),
and
the
more
to continuously track the sun rays with the help of
expensive gallium arsenide, which is produced exclusively for use in photovoltaic (solar) cells.
Solar panels collect solar radiation from
The microcontroller is the heart of the
the sun and actively convert that energy to
proposed embedded system. The controller used is
electricity. Solar panels are comprised of several
a low power, cost efficient chip manufactured by
individual solar cells. These solar cells function
ATMEL having 8K bytes of on-chip flash memory.
similarly to large semiconductors and utilize a
Microcontroller will receive this information and
large-area p-n junction diode. When the solar cells
display on LCD.
are exposed to sunlight, the p-n junction diodes convert the energy from sunlight into usable
POWER SUPPLY:
electrical energy. The energy generated from
A device or system that supplies electrical
photons striking the surface of the solar panel
or other types of energy to an output load or group
allows electrons to be knocked out of their orbits
of loads is called a power supply unit or PSU. The
and released, and electric fields in the solar cells
term is most commonly applied to electrical energy
pull these free electrons in a directional current,
supplies, less often to mechanical ones, and rarely
from which metal contacts in the solar cell can
to others. Here we giving 5v to the micro
generate electricity. The more solar cells in a solar
controller.
panel and the higher the quality of the solar cells, the more total electrical output the solar panel can produce. The conversion of sunlight to usable electrical energy has been dubbed the Photovoltaic
LCD:
Used as real time display, to know the status of the speed of the DC motor.
Effect. BLOCK DIAGRAM H-BRIDGE:
As the time passes the panel rotates with the help of motor. It is a driver circuit to operate the motor. RTC (REAL TIME CLOCK):
Here RTC (Real Time Clock) is used to give the exact time intervals to the controller. SOLAR PANELS:
Fig2.1: Block diagram
Solar panels collect solar radiation from the sun and actively convert that energy to electricity. DC MOTOR:
2.1 BLOCK DIAGRAM EXPLANATION
By using DC motor we are going to turn the panel MICROCONTROLLER:
according to the time. Whenever the radiation of the sun falls on the solar panel it grasps the radiation and stores in it and it will send the
message t t e cont oller about its power which is ¡
¢
stored in it £
II.
HARDWAR E
¨
¤
¥
¦
§
¥
3.1POWER SUPP L
E T ¨
©
St
B id
p
Filt
Fig3.2: Power supply diagram
Circuit Explanation
Fig3.1: Block diagram of power suppl
A) Transformer
A transformer is a device that transfers
Power suppl is a reference to a source of electr ical
power. A device or system that supplies electr ical or other types of energy to an out put load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electr ical energy supplies, less of ten to mechanical ones, and rarely
electr ical energy from one circuit to another through inductively coupled electr ical conductors. A changing current in the f irst circuit (the pr imary) creates a changing magnetic f ield; in turn, this magnetic f ield induces a changing voltage in the second circuit (the secondary). By adding a load to
to others.
the secondary circuit, one can make current f low in This power supply section is required to conver t
the transformer, thus transferr ing energy from one
AC signal to DC signal and also to reduce the
circuit to the other.
amplitude of the signal. The available voltage
The secondary induced voltage VS, of an
signal from the mains is 230V/ 0Hz which is an
ideal transformer, is scaled from the pr i mary VP by
AC voltage, but the required is DC voltage (no
a factor equal to the ratio of the number of turns of
frequency) with the amplitude of +5V and +12V
wire in their respective windings:
for var ious applications. In this section we have Transformer, Br idge rectif ier,
are
connected
ser ially
and
voltage
regulators for +5V and +12V (7805 and 7812) v ia a
B Bridge Rectifier
capacitor (1000µF)
in parallel are connected
A diode br idge or br idge rectif ier is an arrangement
parallel as shown in the circuit diagram below.
of four diodes in a br idge conf iguration that
Each voltage regulator out put is again is connected
provides the same polar ity of out put voltage for any
to the capacitors of values (100µF, 10µF, 1 µF, 0.1
polar ity of input voltage. When used in its most
µF) are connected parallel through which the
common application, for conversion of alternating
corresponding out put (+5V or +12V) are taken into
current (AC) input into direct current (DC) out put,
consideration.
it is known as a br idge rectif ier. A br idge rectif ier
provides full wave rectif ication from a two-wire
AC input, resulting in lower cost and weight as
sometimes called "reverse polar ity protection".
compared to a center-tapped transformer design,
That is, it permits normal functioning when
but has two diode drops rather than one, thus
batter ies are installed backwards or DC input-
exhi biting reduced eff iciency over a center-tapped
power supply wir ing "has its wires crossed" (and
design for t h e s a m e o u t pu t vo l t a g e .
protects the circuitry it powers against damage that might occur without this circuit in place).
Basic Operation
When the input connected at the lef t corner of the diamond is positive with respect to the one connected at the r ight hand corner, current f lows to the r ight along the upper colored path to theout put, and returns to the input supply via the lowerone. Fig 3.5: Wave forms of rectif ier
C) Output smoothing (Using Capacitor)
For many applications, especially with single phase AC where the full-wave br idge serves to conver t an AC input into a DC out put, the addition of a capacitor may be impor tant because Fig3.3: Br idge rectif ier (+ve cycle) When the r ight hand corner is positive relative to the lef t hand corner, current f lows along the upper
the br idge alone supplies an out put voltage of f ixed polar ity but pulsating magnitude (see diagram above).
colored path and returns to the supply via the lower colored path.
Fig 3.6: Smoothing capacitor The function of this capacitor, known as a reservoir capacitor (aka smoothing capacitor) is to lessen the var iation in (or 'smooth') the rectif ied AC Fig 3.4: Br idge rectif ier (-ve cycle) In each case, the upper r ight out put remains positive with respect to the lower r ight one. Since this is true whether the input is AC or DC, this circuit not only produces DC power when supplied with AC power : it also can provide what is
out put voltage waveform from the br idge. One explanation of 'smoothing' is that the capacitor provides a low impedance
path to the AC
component of the out put, reducing the AC voltage across, and AC current through, the resistive load.
In less technical terms, any drop in the output
provide both positive and negative supply voltages
voltage and current of the bridge tends to be
in the same circuit, if necessary.
cancelled by loss of charge in the capacitor.
78xx ICs have three terminals and are most
This charge flows out as additional current
commonly found in the TO220 form factor,
through the load. Thus the change of load current
although smaller surface-mount and larger TrO3
and voltage is reduced relative to what would occur
without
manufacturers.
the
capacitor.
correspondingly
store
Increases excess
of
charge
voltage in
packages
are
also
available
from
some
the
These devices typically support an input
capacitor, thus moderating the change in output
voltage which can be anywhere from a couple of
voltage / current
volts over the intended output voltage, up to a
Output can also be smoothed using a choke and
maximum of 35 or 40 volts, and can typically
second capacitor. The choke tends to keep the
provide up to around 1 or 1.5 amps of current
current (rather than the voltage) more constant. Due
(though smaller or larger packages may have a
to the relatively high cost of an effective choke
lower or higher current rating).
compared to a resistor and capacitor this is not employed in modern equipment.
D) Volt ge Regul tor
A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. The 78xx (also sometimes known as LM78xx) series of devices is a family of self-contained fixed
Fig3.7: Internal block diagram of voltage regulator
linear voltage regulator integrated circuits. The 78xx family is a very popular choice for many electronic circuits which require a regulated power
!
.2 MICROCONTROLLERS:
supply, due to their ease of use and relative MICROPROCESSORS
cheapness. When specifying individual ICs within this family, the xx is replaced with a two-digit number, which indicates the output voltage the particular device is
VS
MICROCONTROLLERS:
Microprocessors are single-chip CPUs used in microcomputers.
designed to provide (for example, the 7805 has a 5 volt output, while the 7812 produces 12 volts). The 78xx line is positive voltage regulators, meaning that they are designed to produce a voltage that is positive relative to a common ground. There is a related
line
of
79xx
devices
which
are
complementary negative voltage regulators. 78xx and 79xx ICs can be used in combination to
Microcontrollers different
in
architecture,
three
and main
applications,
microprocessors aspects: and
are
Hardware
instruction
set
features. Hardware architecture: A microprocessor is a single chip CPU while a microcontroller is a single IC contains a CPU and much of remaining circuitry of a complete computer (e.g., RAM, ROM, serial
interface, parallel interface, timer, and interrupt
Watchdog Timer
handling circuit). The AT89S52 provides the following standard Applications: Microprocessors are commonly
features: 8K bytes of Flash, 256 bytes of RAM, 32
used as a CPU in computers while microcontrollers
I/O lines, Watchdog timer, two data pointers, three
are found in small, minimum component designs
16-bit timer/counters, full duplex serial port, on-
performing control oriented activities.
chip oscillator, and clock circuitry. In addition, the AT89S52 is d esigned with static logic for operation
Microprocessor instruction sets are processing Intensive. They have instructions to set and clear individual bits and perform bit operations.
down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops
the
CPU
while
allowing
the
RAM
timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves
Processing power of a microcontroller is much less than a microprocessor.
the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.
AT89S52: Fe tures:
PIN
DESCRIPTION
OF
"
MICROCONTROLLER 89S52
Compatible with MCS-51Products VCC 8K Bytes of In-System Programmable (ISP) Flash Memory
Supply voltage.
± Endurance: 1000 W rite/Erase Cycles 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz
GND Ground.
Three-level Program Memory Lock 256K Internal RAM 32 Programmable I/O Lines
Por t 0
Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL
3 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel
inputs. When 1sare written to port 0 pins, the pins can be used as high impedance inputs. Port 0 can also be configured to be the multiplexed low order address/data bus during accesses to external program and data memory. In this mode, P0 has
Low-power Idle and P ower-down Modes Interrupt Recovery from Power-down Mode
internal pull-ups.Port 0 also receives the code bytes during Flash Programming and outputs the code
bytes during program verification. External pullups are required du ring program verification Por t 3
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers
Por t 1
can sink/source four TTL inputs. When 1s are writ Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 Output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high by the internal pull-ups and can be used as inputs
1s are written to Port 3 pins, they are pulled high by the internal pull-ups and can be used as inputs. Port 3 also serves the functions of various special features of the AT89S52, as shown in the following table. Port 3 also receives some control signals for Flash programming And verification.
Por t 2
Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the
RST
internal pull-ups and can be used as inputs. Port 2 emits the high-order address byte during fetches from
external
program
memory
and
during
accesses to external data memory that uses 16-bit
Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device.
addresses (MOVX @DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2emits the contents of the P2 S pecial Function Register. Port 2 also receives the high-order address bits and some control signals during Flash programming and verification
ALE/ P ROG
Address Latch Enable (ALE) is an output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming. In normal operation, ALE is emitted
at a constant rate of1/6 the oscillator frequency and
Output from the inverting oscillator amplifier.
may be used for external timing or clocking purposes. Note, however, that one ALE pulse is skipped during each access to external data
Oscill t or Char act r is ti cs #
$
Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit
XTAL1 and XTAL2 are the input and
set, ALE is active only during a MOVX or MOVC
output, respectively, of an inverting amplifier that
instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the micro controller is in external execution mod e.
can be configured for use as an on-chip oscillator, as shown in Figure 1. Either a quartz crystal or ceramic resonator may be used. To drive the device from an External clock source, XTAL2 should be left unconnected while XTAL1 is driven, as shown
P S EN
in
Figure
Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to e xternal data memory.
EA/V PP
External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH.Note, however, that if lock bit
Figure 3.8: Oscillator Connections Speci al Functi on Reg is t er (SFR) Memory:
1 is programmed, EA will be internally latched on reset. A should be strapped to VCC for internal program executions. This pin also receives the 12voltProgramming enables voltage (VPP) during Flash programming.
Special Function Registers (SFR s) are areas of memory that control specific functionality of the 8051 processor. For example, four SFRs permit access to the 8051¶s 32 input/output lines. Another SFR allows the user to set the serial baud rate, control and access timers, and
XT AL1
configure the 8051¶s i nterrupt system.
Input to the inverting oscillator amplifier and input to the internal clock operating circuit. Accumul at or: XT AL2
The Accumulator, as its name suggests is used as a general register to accumulate the results of a large number of instructions. It can hold 8-bit (1-byte) value and is the most versatile register. R´ r eg is t er s: ³
The ³R´ registers are a set of eight registers that are named R0, R1. Etc up to R7. These registers are used as auxiliary registers in many operations. Fig 3.9: LCD pin description The ³B´ registers: The ³B´ register is very similar to the accumulator in the sense that it may hold an 8-bit (1-byte) value. Two only uses the ³B´ register 8051 instructions: MUL AB and DIV AB.The Data Pointer: The Data pointer (DPTR) is the 8051¶s only user accessible 16-bit (2Bytes) register. The
LCD PI N D E SCR IP T I O N
The LCD which we have used in our project is a 16×2 alpha numeric LCD. It has 16 pins. Figure shows the position of various pins.
accumulator, ³R´ registers are all 1-Byte values. DPTR, as the name suggests, is used to point to data. It is used by a number of commands, which allow the 8051 to access external memory.
1. V CC, V SS, and VEE
While VCC and VSS provide +5V and ground, respectively, VEE is used for controlling LCD contrast.
3.3 LCD (LIQUID CRISTAL DISPLAY)
1. The declining prices of LCDs make its use cost2. RS (Reg is t er Sel ect )
effective. 2. The ability to display numbers, characters and graphics. This is contrast to LEDs, which limited
to
numbers
and
few
has
characters.
Incorporation of a refreshing controller into LCD, thereby relieving the CPU of the task of refreshing the LCD. In contrast, the LED must be refreshed by the CPU to keep displaying data.
There are two very important registers inside the LCD. The RS pin is used for their selection as follows. If RS=0, the instruction command code register is selected, allowing the user to send a command such as clear display, cursor at home, etc. If RS=1, the data register is selected, allowing the user to send data to be displayed on LCD.
3. Ease of programming for characters and
3. R /W (Read /W r it e)
R/W input allows the user to write information to LCD or read information from it.
R/W=1 when reading; R/W=0 when writing.
E Display on, cursor blinking F Display on, cursor blinking
4. E ( E nabl e)
The enable pin is used by the LCD to latch
80 Force cursor to beginning of 1st line C0 Force cursor to beginning of 2nd lin e
information presented to its data pins. When data is supplied to data pins, a high-to-low pulse must be applied to this pin in order for the LCD to latch in
3.4DC MOTOR:
the data present the data pins. This pulse must be a A DC motor is designed to run on DC
minimum of 450 ns wide.
electric power. Two examples of pure DC designs 5. D0- D7 (8-bit Dat a bus)
The 8-bit data pins, D0-D7, are used to send information to the LCD or read th e contents of the LCD¶s internal registers. To display letters and numbers, we send ASCII codes for the letters A-Z, a-z, and numbers 0-9 to these pins whil e making
are Michael Faraday's homopolar motor (which is uncommon), and the ball bearing motor, which is (so far) a novelty. By far the most common DC motor types are the brushed and brushless types, which use internal and external commutation respectively to create an oscillating AC current from the DC source -- so they are not purely DC
. 6
machines in a strict sense.
RS=1
There are also instruction command codes that can be sent to LCD to clear the cursor to the home position or blink the cursor. Table lists some of the instruction command codes. Code Command to LCD Instruction Register (Hex) 1 Clear Display screen Fig3.10: DC Motor
2 Return home 4 Shift cursor left
T y pes of dc mot or s:
6 Shift cursor right
1.
Brushed DC Motors
2.
Brushless DC motors
3.
Coreless DC motors
5 Shift Display right 7 Shift Display left 8 Display off, cursor off
4. Brushed DC motors: The classic DC motor design generates an oscillating current in a wound rotor with a split
A Display off, cursor on C Display on, cursor off
ring commutator, and either a wound or permanent magnet stator. A rotor consists of a coil wound around a rotor which is then
powered by any type of battery.Many of the
disk drives or in video cassette recorders, the
limitations of the classic commutator DC
spindles within CD, CD-ROM (etc.) drives, and
motor are due to the need for brushes to press
mechanisms within office products such as fans,
against the commutator. This creates friction.
laser printers and photocopiers. They have several
At higher speeds, brushes have increasing
advantages over conventional motors:
difficulty in maintaining contact. Brushes may
y
Compared to AC fans using shaded-pole
bounce off the irregularities in the commutator
motors, they are very efficient, running much
surface,
the
cooler than the equivalent AC motors. This
maximum speed of the machine. The current
cool operation leads to much-improved life of
density per unit area of the brushes limits the
the fan's bearings.
creating
sparks.
This
limits
output of the motor. The imperfect electric
y
Without a commutator to wear out, the life of a
contact also causes electrical noise. Brushes
DC brushless motor can be significantly longer
eventually wear out and require replacement,
compared to a DC motor using brushes and a
and the commutator itself is subject to wear
commutator. Commutation also tends to cause
and maintenance.
a great deal of electrical and RF noise; without a commutator or brushes, a brushless motor
Br ushl ess DC mot or s :
may be used in electrically sensitive devices like audio equipment or co mputers.
Some of the problems of the brushed DC motor are eliminated in the brushless design. In this motor,
the
mechanical
"rotating
switch"
or
commutator/brush gear assembly is replaced by an
y
The motor can be easily synchronized to an internal or external clock, leading to precise speed control.
external electronic switch synchronized to the rotor's position. Brushless motors are typically 85-
C or el ess DC mot or s:
90% efficient, whereas DC motors with brush gear
Nothing in the design of any of the motors
are typically 75-80% efficient.
described above requires that the iron (steel) portions of the rotor actually rotate; torque is
Midway between ordinary DC motors and stepper
exerted only on the windings of t he electromagnets.
motors lies the realm of the brushless DC motor.
Taking advantage of this fact is the coreless DC
Built in a fashion very similar to stepper motors,
motor, a specialized form of a brush or brushless
these often use a permanent magnet external rotor,
DC motor.
three phases of driving coils, one or more Hal
Optimized for rapid acceleration, these
effect sensors to sense the position of the rotor, and
motors have a rotor that is constructed without any
the associated drive electronics. The coils are
iron core. The rotor can take the form of a winding-
activated, one phase after the other, by the drive
filled cylinder inside the stator magnets, a basket
electronics as cued by the signals from the Hall
surrounding the stator magnets, or a flat pancak e
effect sensors. In effect, they act as three-phase
(possibly formed on a printed wiring board)
synchronous motors containing their own variable-
running between upper and l ower stator magnets.
frequency drive electronics.
These motors were commonly used to
Brushless DC motors are commonly used where
drive the capstan(s) of magnetic tape drives and are
precise speed control is necessary, as in computer
still widely used in high-performance servo-
controlled
systems,
vehicles/aircraft,
like
humanoid
radio-controlled robotic
systems,
industrial automation, medical devices, etc.
3.5 H-BRIDGE (MOTOR DRIVER)
Fig3.12: The two basic states of an H-bridge The H-Bridge arrangement is generally used to reverse the polarity of the motor, but can also be used to 'brake' the motor, where the motor comes to a sudden stop, as the motor's terminals are shorted, or to let the motor 'free run' to a stop, as the motor is effectively disconnected from the circuit. The following table summarizes operation.
Fig3.11: Structure of an H-bridge (highlighted in S1 S2 S3 S4 Result
red)
An H-bri ge is an electronic circuit which %
1 0
0
1
Motor moves right
0 1
1
0
Motor moves left
0 0
0
0
Motor free runs
0 1
0
1
Motor brakes
1 0
1
0
Motor brakes
enables a voltage to be applied across a load in either direction. These circuits are often used in robotics and other applications to allow DC motors to run forwards and backwards. H-bridges are available as integrated circuits
The term "H-
bridge" is derived from the typical graphical representation of such a circuit. An H-bridge is built with four switches . When the switches S1 and S4 (according to the first figure) are closed (and S2 and S3 are open) a positive voltage will be applied across the motor. By opening S1 and S4 switches and closing S2 and S3 switches, this voltage is reversed, allowing reverse operation of the motor.
Oper ati on:
C onst ru cti on
often refers to the devices in personal computers, servers and embedded systems, RTCs are present in Fig3.13: Typical solid state H-bridge A solid-state H-bridge is typically constructed
almost any electronic device which needs to keep accurate time.
using reverse polarity devices (i.e., PNPBJTs or Pchannel MOSFETs connected to the high voltage bus and NPN BJTs or N-channel MOSFETs
Ter mi nol o g y
connected to the low voltage bus). The term is used to avoid confusion with The most efficient MOSFET designs use N-channel
ordinary hardware clocks which are only signals
MOSFETs on both the high side and low side
that govern digital electronics, and do not count
because they typically have a third of the ON
time in human units. RTC should not be confused
resistance of P-channel MOSFETs. This requires a
with real-time computing, which shares its three-
more complex design since the gates of the high
letter acronym, but does not directly relate to time
side MOSFETs must be driven positive with
of day.
respect to the DC supply rail. However, many integrated circuit MOSFET drivers include a charge pump within the device to achieve this.
P ur pose
Alternatively, a switch-mode DC-DC converter can
Although keeping time can be done without an
be used to provide isolated ('floating') supplies to
RTC, using one has benefits:
the gate drive circuitry. A multiple-output fly back converter is well-suited to this application.
y
Low power consumption (important when running from alternate power)
A "double pole double throw" relay can generally y
Frees the main system for time-critical tasks
y
Sometimes more accurate than other methods
achieve the same electrical functionality as an H bridge (considering the usual function of the device). An H-bridge would be preferable to the relay where a smaller physical size, high speed switching, or low driving voltage is needed, or where the wearing out of mechanical parts is undesirable.
A GPS receiver can shorten its startup time by comparing the current time, according to its RTC, with the time at which it last had a valid signal. If it has been less than a few hours then the previous ephemeris is still usable.
3.6 REAL-TIME CLOCK Power sour ce
Dallas semiconductor real-time clock from an older PC. This version also contains a battery backed SRAM.
RTCs often have an alternate source of power, so they can continue to keep time while the primary source of power is off or unavailable. This
A re l-ti e clock (RTC) is a computerclock &
'
(most often in the form of an in tegrated circuit) that keeps track of the current time. Although the term
alternate source of power is normally a lithium battery in older systems, but some newer systems use a supercapacitor, because they are rechargeable
and can be soldered. The alternate power source can also supply power to battery backed RAM.
System
time
can
be
converted
into
c le d r time, which is a form more suitable for )
0
)
human comprehension. For example, the Unix system time that is 1,000,000,000 seconds since the beginning of the epoch translates into the calendar
T im i ng
time 9 September 2001 01:46:40 UT. Library Most RTCs use a crystal oscillator, but some use the power line frequency. In many cases the oscillator's frequency is 32.768 kHz. This is the same frequency used in quartz clocks and watches, and for the same reasons, namely that the frequency is exactly 2
15
cycles per second, which is
subroutines that handle such conversions may also deal with adjustments for time zones, Daylight Saving Time (DST), leap seconds, and the user's locale settings. Library routines are also generally provided that convert calendar times into system times.
a convenient rate to use with simple binary counter Closely related to system time is
circuits.
1
rocess
time, which is a count of the total CPU time
consumed by an executing process. It may be split into user and syst em CPU time, representing the
S yst em ti me
time spent executing user code and system kernel In
computer
science
and
computer
code, respectively. Process times are a tally of CPU
programming, system time represents a computer
instructions or clock cycles and generally have no
system's notion of the passing of time. In this sense,
direct correlation to wall time.
time also includes the passing of days on the File systems keep track of the times that
calendar.
files are created, modified, and/or accessed by System time is measured by a system clock , which is typically implemented as a simple
storing timest m s in the file control block (or 2
3
inode) of each file and directory.
count of the number of ticks that have transpired since some arbitrary starting date, called the e och.
It should be noted that most first-generation PCs
For example, Unix and POSIX-compliant systems
did not keep track of dates and times. Retrieving
encode system time as the number of seconds
system time.
(
elapsed since the start of the epoch at 1 January 1970 00:00:00 UT. Windows NT counts the number of 100-nanosecond ticks since 1 January
3.7 SOLAR PANEL
1601 00:00:00 UT as reckoned in the proleptic Gregorian calendar, but returns the current time to the nearest millisecond.
S ol ar panel speci f ic ati ons:
Solar panels use sunlight to re-charge RV batteries. The process is called PHOTOVOLTAICS (PV). We stock panels that have a life expectancy
N I X U
dat e command
of over 30 years and have a manufacturer's warranty on output of 25 years long. We prefer the brands that use "solid crystal silicon" cells for the
highest efficiency as they work well under adverse conditions -- even on rainy days.
Because a single photovoltaic module can only produce a limited amount of power, many installations contain several modules or panels and
The strong aluminum frame is glazed with special clear and toughened tempered glass that may withstand hailstones and other hazards. We expect these long-life panels made by SHELL, BP
this
is
known
as
a
photovoltaic
array.
A
photovoltaic installation typically includes an array of photovoltaic modules or panels, an inverter, batteries and interconnection wiring.
SOLAR, KYOCERA/SHARP/ and others will work for 30 years or more.
Photovoltaic systems are used for either on- or offgrid
P hot ovolt ai c modul e:
applications,
and
for
solar
panels
on
spacecraft.
"Solar panel" redirects here. For the heat collectors, see Solar thermal collector. W ork in g of SO LA R panel :
Solar panels collect solar radiation from the sun and actively convert that energy to electricity. Solar panels are comprised of several individual solar cells. These solar cells function similarly to large semiconductors and utilize a large-area p-n junction diode. When the solar cells are exposed to sunlight, the p-n junction diodes convert the energy from sunlight into usable electrical energy. The energy generated
Fig3.14: Photovoltaic module
from photons striking the surface of the solar panel allows electrons to be knocked out of their orbits and released, and electric fields in the solar cells A photovoltaic module is composed of individual PV cells. This crystalline-silicon module has an aluminium frame and glass on the front.
pull these free electrons in a directional current, from which metal contacts in the solar cell can generate electricity.
A PV module on the ISS.
The more solar cells in a solar panel and
A photovolt ic module or photovolt ic
the higher the quality of the solar cells, the more
panel is a packaged interconnected assembly of
total electrical output the solar panel can produce.
photovoltaic cells, also known as solar cells. The
The conversion of sunlight to usable electrical
photovoltaic module, known more commonly as
energy has been dubbed the P hotovolt aic Eff ect .
4
4
the solar panel, is then used as a component in a larger photovoltaic system to offer electricity for commercial and residential applications.
S ol ar I nsol ati on and S ol ar P anel E ff ic i enc y:
Solar Insolation is a measure of how much
Third generation solar cells are advanced
solar radiation a given solar panel or surface
thin-film
cells.
They
receives. The greater the insolation, the more solar
conversion at low cost.
produce
high-efficiency
energy can be converted to electricity by the solar panel. Click to learn more about solar insolation. Other factors that affect the output of solar
Ri g i d t hi n- f il m modul es:
panels are weather conditions, shade caused by
In rigid thin film modules, the cell and the
obstructions to direct sunlight, and the angle and
module are manufactured in the same production
position at which the solar panel is installed. Solar
line.
panels function the best when placed in direct The cell is created directly on a glass
sunlight, away from obstructions that might cast shade, and in areas with high regional solar
substrate
or
superstrate,
and
the
electrical
connections are created in sit u , a so called
insolation ratings.
"monolithic Solar panel efficiency can be optimized by using dynamic mounts that follow the position of
integration".
The
substrate
or
superstrate is laminated with an encapsulant to a front or back sheet, usually another sheet of glass.
the sun in the sky and rotate the solar panel to get The
the maximum amount of direct exposure during the
main
cell
technologies
in
this
category are CdTe, or a-Si, or a-Si+uc-Si tandem,
day as possible.
or CIGS (or variant). Amorphous silicon has a sunlight conversion rate of 6-12%. Curr ent r esear ch on mat er i al s and devi ces:
Developing new technologies based on
F le x i bl e t hi n- f il m modul es:
new solar cell architectural designs ; and developing Flexible thin film cells and modules are
new materials to serve as light absorbers and
created on the same production line by depositing
charge carriers.
the photoactive layer and other necessary layers on a flexible substrate. C ryst alli ne sili con modul es:
If the substrate is an insulator (e.g. Most
solar
module
are
currently
produced from silicon PV cells. These are typically
polyester or polyimide film) then monolithic integration can be used.
categorized into either mono crystalline or multi crystalline modules.
If it is a conductor then another technique for electrical connection must be used.
M odul e perfor mance and li f eti me: Thi n- f il m modul es:
Module performance is generally rated under
Standard
Test
Conditions
(STC) :
irradianceof 1,000 W/m², solar spectrum of AM 1.5 and
module
temperature
at
t ory H is
of sol ar cell s:
The term " photovoltaic" comes from the
25°C.Electrical (P MAX ,
Greek ( phs) meaning "light", and "voltaic",
measured in W), open circuit voltage (V OC ), short
meaning electric, from the name of the Italian
circuit
amperes),
physicist Volta, after whom a unit of electro-motive
maximum power voltage (V MPP ), maximum power
force, the volt, is named. The term " photo-voltaic"
current (IMPP ) and module efficiency (%).Solar
has been in use in English since 1849.
characteristics
include
current
(ISC ,
nominal
power
measured
in
panels must withstand heat, cold, rain and hail for
The
photovoltaic
effect was
first
many years. Many Crystalline silicon module
recognized in 1839 by French physicist A. E.
manufacturers offer warranties that guarantee
Becquerel. However, it was not until 1883 that the
electrical production for 10 years at 90% of rated
first solar cell was built, by Charles Fritts, who
power output and 25 years at 80% .
coated
the
semiconductorselenium
with
an
extremely thin layer of gold to form the junctions. S ol ar cell :
The
A solar cell is a device that converts the energy of sunlight directly into electricity by the photovoltaic effect. Sometimes the term sol ar cell is reserved for devices intended specifically to capture energy from sunlight such as solar panels and solar cells, while the term photovolt aic cell is used
when
the
light
source
is
unspecified.
Assemblies of cells are used to make solar panels, solar
modules,
P hotovolt aic s
or
photovoltaic
arrays .
is the field of technology and
device
was
only
around
1%
efficient.
Subsequently Russian physicist AleksandrStoletov built the first solar cell based on the outer photoelectric effect (discovered by Heinrich Hertz earlier in 1887). Albert Einstein explained the photoelectric effect in 1905 for which he received the Nobel Prize in Physics in 1921. Russell Ohl patented the modern junction semiconductor solar cell in 1946, which was discovered while working on the series of advances that would lead to the transistor .
research related to the application of solar cells in producing electricity for practical use. The energy generated this way is an example of sol ar energy (also known as sol ar power ).
S im pl e expl anati on for work in g of sol ar panel :
1. Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon. 2. Electrons (negatively charged) are knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to the special composition of solar cells, the electrons are only allowed to move in a single direction. 3. An array of solar cells converts solar energy into a usable amount of direct current (DC)
Fig3.15: Solar cell
electricity.
way, but rather by diffusing an n-type dopant into one side of a p-type wafer (or vice versa).
P hot o gener ati on of char ge carr ie r s:
When a photon hits a piece of silicon, one of three things can happen:
intimate contact with a piece of n-type silicon, then
1. The photon can pass straight through the silicon this (generally) happens for lower
5
If a piece of p-type silicon is placed in
energy
photons.
a diffusion of electrons occurs from the region of high electron concentration (the n-type side of the junction)
into
the
region
of
low
electron
2. The photon can reflect off the surface.
concentration (p-type side of the junction). When
3. The photon can be absorbed by the silicon, if
the electrons diffuse across the p-n junction, they
the photon energy is higher than the silicon
recombine with holes on the p-type side. The
band gap value. This generates an electron-hole
diffusion of carriers does not happen indefinitely,
pair and sometimes heat, depending on the band
however, because charges build up on either side of
structure.
the junction and create an electric field. The electric field creates a diode that promotes charge flow,
Char ge carr ie r separ ati on:
known as drift current, that opposes and eventually
There are two main modes for charge carrier
balances out the diffusion of electron and holes.
separation in a solar cell:
This region where electrons and holes have
1. Dri t of carriers, driven by an electrostatic field 6
established across the de vice
region because it no longer contains any mobile
2. Di usion of carriers from zones of high carrier 7
diffused across the junction is called the depletion
7
concentration
to
zones
of
low
carrier
concentration
(following
a
gradient
charge carriers. It is also known as the s pace charge reg ion.
of
electrochemical potential).
C onnecti on t o an ex te r nal l oad :
In the widely used p-n junction solar cells,
Ohmicmetal-semiconductor contacts are
the dominant mode of charge carrier separation is
made to both the n-type and p-type sides of the
by drift. However, in non-p-n-junction solar cells
solar cell, and the electrodes connected to an
(typical of the third generation solar cell research
external load. Electrons that are created on the n-
such as dye and polymer solar cells ), a general
type side, or have been "collected" by the junction
electrostatic field has been confirmed to be absent,
and swept onto the n-type side, may travel through
and the dominant mode of separation is via charge
the wire, power the load, and continue through the
carrier diffusion.
wire until they reach the p-type semiconductormetal contact. Here, they recombine with a hole that was either created as an electron-hole pair on
The p-n juncti on:
The most commonly known solar cell is configured as a large-area p-n junction made from silicon. As a simplification, one can imagine bringing a layer of n-type silicon into direct contact with a layer of p-type silicon. In practice, p-n junctions of silicon solar cells are not made in this
the p-type side of the solar cell, or a hole that was swept across the junction from the n-type side after being created there. The voltage measured is equal to the difference in the quasi Fermi levels of the minority carriers, i.e. electrons in the p-type portion and holes in the n-type portion.
SOLAR CELL EFFICIENCY FACTORS:
VOC ratio, and fill factor. Resistive losses are
E ner g y conver si on e ff ic i enc y:
predominantly categorized under fill factor, but
A solar cell's energy conversion e fficienc y
also make up minor portions of the quantum
(, "eta"), is the percentage of power converted
efficiency, V OC ratio.
(from absorbed light to electrical energy) and collected, when a solar cell is connected to an
Bul k t echnol o g y:
These bul k technologies are often referred
electrical circuit. This term is calculated using the ratio of the maximum power point,
P m,
divided by
to as wafer-based manufacturing. In other words, in
the input light irr ad iance ( E , in W/m2) under
each of these approaches, self-supporting wafers
standard test conditions (STC) and the sur f ace area
between
2
of the solar cell ( Ac in m ).
180
to
240 micrometers
thick
are
processed and then soldered together to form a solar cell module. C ryst alli ne sili con:
STC specifies a temperature of 25 °C and an irradiance of 1000 W/m 2 with an air mass 1.5 (AM1.5) spectrum. These correspond to the irradiance and spectrum of sunlight incident on a clear day upon a sun-facing 37°-tilted surface with the sun at an angle of 41.81° above the horizon. This condition approximately represents solar noon near the spring and autumn equinoxes in the continental United States with surface of the cell aimed directly at the sun. Thus, under these conditions a solar cell of 12% efficiency with a 100 cm2 (0.01 m2) surface area can be expected to produce approximately 1.2 watts of power. The efficiency of a solar cell may be
broken
down
thermodynamic
into
reflectance
efficiency,
charge
Fig3.16: Basic structure of a silicon based solar cell
efficiency,
and its working mechanism
carrier By far, the most prevalent
separation efficiency and conductive efficiency.
bul k
material
The overall efficiency is the product of each of
for solar cells is crystalline silicon (abbreviated as a
these individual efficiencies.
group as c-S i), also known as "solar grade silicon ".
Due to the difficulty in measuring these
Bulk silicon is separated into multiple categories
parameters directly, other parameters are measured
according to crystallinity and crystal size in the
instead:
resulting ingot, ribbon, or wafer .
thermodynamic
efficiency,
quantum
efficiency, V OC ratio, and fill factor. Reflectance losses are a portion of the quantum efficiency under "external
quantum
efficiency".
Recombination
losses make up a portion of the quantum efficiency,
1.
M ono
cryst alline silicon (c-Si): often made using
the Czochralski process. Single-crystal wafer cells tend to be expensive, and because they are cut from cylindrical ingots, do not completely cover a square
solar cell module without a substantial waste of
*Express SCH for schematic d esign
refined silicon. Hence most c-S i panels have uncovered gaps at the four corners of the cells. 2.
y P ol
or multi cryst alline silicon (poly-Si or mc-Si):
made from cast square ingots
8
4.2 KEIL SOFTWARE
large blocks of Installing the Keil software on a Windows PC
molten silicon carefully cooled and solidified. Poly-Si cells are less expensive to produce than
y
single crystal silicon cells, but are less efficient. US
drive.
DOE data shows that there were a higher number y
of multi crystalline sales than mono crystalline
On most computers, the CD will ³auto run´, and you will see the Keil installation menu. If
silicon sales. Ribbon
Insert the CD-ROM in your computer¶s CD
the menu does not appear, manually double silicon
is
a
type
of
multi
click on the Setup icon, in the root directory:
crystalline silicon: it is formed by drawing flat thin
you will then see the Keil menu.
films from molten silicon and results in a multi y
crystalline structure. These cells have lower
On the Keil menu, please select ³Install Evaluation Software´. (You will not require a
efficiencies than poly-Si, but save on production
license number to install this software).
costs due to a great reduction in silicon waste, as y
this approach does not require sawing from in gots.
Follow the installation instructions as they appear.
Loading the Projects Li f espan:
The example projects for this book are NOT loaded
Most commercially available solar cells
automatically when you install the Keil compiler.
are capable of producing electricity for at least
These files are stored on the CD in a directory
twenty years without a significant decrease in
³/Pont´. The files are arranged by chapter: for
efficiency. The typical warranty given by panel
example, the project discussed in Chapter 3 is in
manufacturers is for a period of 25 - 30 years,
the directory ³/P ont/Ch03_00-Hello´.
wherein the output shall not fall below 85% of the rated capacity.
Rather than using the projects on the CD (where changes cannot be saved), please copy the files
C ost s:
from CD onto an appropriate directory on your Cost is established in cost-per-watt and in
hard disk.
cost-per-watt in 24 hours for infrared capable Note: you will need to change the file properties
photovoltaic cells.
after copying: file transferred from the CD will be µread only¶.
SOFTWARE COMPONENTS 4.1 EMBEDDED ¶C¶
Software¶s used are: *Keil software for c programming III.
*Express PCB for lay out design
RESULT ANALYSIS
Case (i): Case (iii):
Fig
5.1:
Panel
inclination
at
initial
condition Fig 5.3: Panel inclination at noon period
At the initial condition, the panel is perpendicular to the sunlight with ZERO inclination.
At the noon period, the sun¶s radiation is perpendicular to the earth surface. At this time, the panel is parallel to earth surface i.e., perpendicular to sun¶s radiation as usual.
Case (ii):
FUTURE ASPECTS
y
By using special sensors we can get exact sun tracking instead of time based t racking system.
y
Fig 5.2: Panel inclination after one hour
By preparing infrared solar panels we may generate power even in night times and also in cloudy days.
y
Infrared solar panels are differing from traditional solar panels in the glass cover of collector only.
After one Hour duration, the sun is elevated.
y
To turn a photovoltaic solar cell into an infrared
According to sun direction the panel is also
solar energy panel the glass has to be treated during
elevated with inclination of 15 o.
the production phase. It is turned into low ironed
tempered glass as opposed to normal ironed
Void main()
tempered glass. y
By producing low ironed tempered glass, it means that the system can absorb high wavelength
{ b2temp=rcount=0 ;
sunlight. The high wave length range is from 800 to 1200nm and this is the infrared range. A lower wave length from 400 to 800nm is the normal
lcd_init(); display(100);
visible sunlight. lcd_init(); APPENDIX
display(100); lcdcmd(0×84);
Code:
msgdisplay(³WELCOME´);
#include
display(1000);
#include
lcdcmd(0×01);
#include ³lcddisplsy.h´
msgdisplay(³SOLAR TRACKER´);
#include ³eeprom.h´
lcdcmd(0×01);
Sbit
in1 = p2^2;
/*****start rtc chip*****
Sbit
in1 = p2^3;
/Write_eeprom(0,0)
Sbit
in1 = p2^4;
Display(500);
Sbit
in1 = p2^5;
Write_eeprom(1,0); Display(500);
Sbit
sw = p3^1;
Write_eeprom(1,0); Display(500);
Unsigned char B1 , B2 , B3 , Z ; Unsigned char l , s , n , a , b , I , count , b2temp ,
Msgdisplay(³
TIME:´);
rcount ; While(1) Unsigned int x ; { Bit BK=0 ; Xx:lcdcmd(0×c1);
For(i=3;i>0;i- -)
if(rcount==20)
{
rcount=0; Z=read_eeprom(i-1);
b2temp=z;
B1=z&0×0f ;
delay(200);
B2=(z&0×f0)>>4;
en1=0;
Lcddata(B2+0×30);
in1=in2=0;
Lcddata(B1+0×30);
}
If(I !=1)
}
Lcddata( µ : µ);
For(x=0;x<1000;x++) //check for switch
If(i==2)
{
{
if(sw==0)
//if switch is pressed then
rotate the base If(b2temp!=z) { { delay(1000); En1=1; while(sw==0); If(rcount<10)
//rotate in clockwise
direction
en2=1; {
in3=1;
In1=1;
in4=0;
In2=0;
delay(1000);
}
while(sw==1);
Else
// rotate in anticlockwise direction
en2=0;
{
in3=0;
In1=0;
in4=0;
In2=1;
while(sw==0);
}
goto xx; rcount=rcount+1;
}
} } }} BIBLIOGRAPHY Reference Books: CONCLUSION
1.
The 8051 Micro controller and Embedded Systems
by
Muhammad
Ali
Mazidi,
Janice Gillispie Mazidi By using solar energy for power generation we are
2.
saving the conventional energy sources for future generation to maintain balanced power generation.
computers by B. Ram 3.
and very low efficiency process by using solar tracking system connecting to the solar panel such
Gaonkar 4.
Electrical Machines By P.S.Bimbra
5.
.Non-Conventional Energy Sources by Rai
that the panel is always perpendicular to the sun elevation. It is convenient for the higher power generation. But it also has a drawback of highly economic.
Micro processor Architecture, Programming & Applications by Ramesh S.
In our project, we are going to replace the traditional solar energy collection which is a costly
Fundamentals of Micro processors and Micro
References on the Web:
1.
www.national.com
2.
www.atmel.com
3.
www.microsoftsearch.com
4.
www.geocities.com
G.D.
