Black Book 1 Rough'

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ABSTRACTWith the unprecedented nuclear disaster raising disturbing questions on safety and the global political conflict

threatening to cease significant oil supply to India, there is a need now more than ever before to harness the power

of the inexhaustible sources of energy. Of these, solar energy has the most unexplored potential. Not only will

prices of essential exhaustible fossil fuels be brought down but also it will drastically reduce the impact of industries

on the environment. Not only would these benefits remain sustainable in the long run but also energy security would

phenomenally increase

INTRODUCTION

Solar energy is the future when it comes to energy requirement of humans . About 47 per cent of the energy thatthe sun releases to the earth actually reaches the ground. About a third is reflected directly back into space by the

atmosphere. The time in which solar energy is available, is also the time we least need it least - daytime. Because

the sun's energy cannot be stored for use another time, we need to convert the suns energy into an energy that

can be stored. The solar panels generate low grade heat, that is, they generate low temperatures for the amount

of heat needed in a day. The energy can be harnessed with help of Solar Panels. However this energy is highly

inefficient in terms of the energy density (power/area).Therefore we need a method to ensure that the energy

being cultivated is harnessed efficiently.The Sun is a star, around which Earth keeps rotating and revolving. Due to

its rotation, relatively the Sun moves 360 degrees around the earth with respect to Earth . Therefore there comes

the requirement of facing the Solar Energy harnessing equipment continuously to the Sun.The project aims at

achieving this by automatically adjusting the alignment of the Solar Panel with respect to the Sun .

The system with help of some other techniques would ensure further energy efficiency in terms of storing Solar

Energy.

LITERATURE SURVEY

1]OP-Amp:

The circuit symbol for an op-amp is shown below,

Where:

V+: non-inverting input V-: inverting input VOUT: output Vs+: positive power supply Vs-: negative power supply


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The power supply pins (Vs+ and Vs-) can be labeled in different ways. Despite different labeling, the function

remains the same to provide additional power for amplification of the signal. Often these pins are left out of the

diagram for clarity, and the power configuration is described or assumed from the circuit.

Fig.3.1 (a) OP-Amp

The amplifier's differential inputs consist of a V+ input and a V- input, and ideally the op-amp amplifies only the

difference in voltage between the two, which is called the differentialinput voltage. The output voltage of the op-

amp is given by the equation,

Vout = (V+-- V-) AOL

Where V+ is the voltage at the non-inverting terminal, V- is the voltage at the inverting terminal andAOL is the open-

loop gain of the amplifier (the term "open-loop" refers to the absence of a feedback loop from the output to the

input).

The magnitude ofAOL is typically very large for integrated circuit op-amps and therefore even a quite small

difference between V+ and V- drives the amplifier output nearly to the supply voltage. This is called saturation of the

amplifier.

2] Properties of Ideal OP-Amp

internal connections of op-amp

An ideal op-amp is usually considered to have the following properties, and they are considered to hold for all input

voltages:
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Infinite open-loop gain (when doing theoretical analysis, a limit may be taken as open loop gain AOL goesto infinity).

Infinite voltage range available at the output (vout) (in practice the voltages available from the output arelimited by the supply voltages VS+ and VS-). The power supply sources are called rails.

Infinite bandwidth (i.e., the frequency magnitude response is considered to be flat everywhere with zerophase shift).

Infinite input impedance (so, in the diagram, RIN= infininty, and zero current flows from V+ to V-). Zero input current (i.e., there is assumed to be no leakage or bias current into the device). Zero input offset voltage (i.e., when the input terminals are shorted so that V+ = V-, the output is a virtual

ground or vout = 0).

Infinite slew rate (i.e., the rate of change of the output voltage is unbounded) and power bandwidth (fulloutput voltage and current available at all frequencies).

Zero output impedance (i.e., Rout = 0, so that output voltage does not vary with output current). Zero noise. Infinite Common-mode rejection ratio (CMRR). Infinite Power supply rejection ratio for both power supply rails.

These ideal properties can be summarized by the two "golden rules":

I. The output attempts to do whatever is necessary to make the voltage difference between the inputs zero.

II. The inputs draw no current.

The first rule only applies in the usual case where the op-amp is used in a closed-loop design (negative feedback,

where there is a signal path of some sort feeding back from the output to the inverting input). These rules are

commonly used as a good first approximation for analyzing or designing op-amp circuits.

In practice, none of these ideal properties can be perfectly realized, and various shortcomings and compromises have

to be accepted. Depending on the parameters of interest, a real op-amp may be modeled to take account of some of

the non-infinite or non-zero parameters using equivalent resistors and capacitors in the op-amp model. The designer

can then include the effects of these undesirable, but real, effects into the overall performance of the final circuit.

Some parameters may turn out to have negligible effect on the final design while others represent actual limitations

of the final performance that must be evaluated.

Applications of Op-Amp:

Voltage follower

Inverting amplifier

Non-inverting amplifier

Nonlinear (algorithmic) amplifier

Differential amplifier

Summing amplifier


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Differentiator

Integrator

3] Differential Amplifier:

Thus far we have used only one of the operational amplifiers inputs to connect to the amplifier, using either the

inverting or the non-inverting input terminal to amplify a single input signal with the other input being

connected to ground. But we can also connect signals to both of the inputs at the same time producing another

common type of operational amplifier circuit called a Differential Amplifier.

Basically, as we saw in the first tutorial about operational amplifiers, all op-amps are Differential Amplifiers due

to their input configuration. But by connecting one voltage signal onto one input terminal and another voltage signal

onto the other input terminal the resultant output voltage will be proportional to the Difference between the two

input voltage signals of V1 and V2. Then differential amplifiers amplify the difference between two voltages

making this type of circuit a Subtractor unlike a summing amplifier which adds or sums together the input voltages.

This type of operational amplifier circuit is commonly known as a Differential Amplifier configuration and is

shown below:

Fig. 3.2Differential Amplifier

4] Different modes of rotations solar panels:

1) 180o rotation of the solar panel:A duel axis tracking module is designed in such a way that the rotation of the solar panel is in 180

o. This

arrangement is basically done raising the solar panel above vertically by means of a rod and panel is made movable

along the Y axis in 180o. This is also known as dual axis rotation of solar panel.

2) 360o rotation of the solar panel:


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A single axis tracking of the solar PV module is implemented with 360o

rotation mechanism. For tracking the sun,

the module is made to rotate 360o

angle in a day, i.e. one rotation in 24 hours. The module starts its rotation from

vertical position at the time of sunrise facing towards east (perpendicular to ground) and rotates at the rate of 15 per

hour as shown in figure below. This tracking mechanism is based on the angle of rotation of earth around its own

axis. The time for rotation of earth around its own axis is 24 hours which is equal to the tracking time of this system.

This system is always in synchronization with the rotation of earth without any extra component because, this

system starts at the time of sunrise and goes on and on as earth rotates on its own axis. That is the reason this

tracking system does not require any sensor or extra component for synchronization like any other tracking system.

Fig 3.3 360o

rotation of the solar panel

SOLAR PANEL

Poly Crystalline (also called multi crystalline):

These solar PV panels are also made from silicon, but the silicon used is slightly less pure and they are cast into

blocks rather than sawn from a single crystal. This is why the crystals are visible - they are randomly arranged.

Once cast, they are sawn into square blocks and then into wafers and cells like mono crystalline, but a little easier to

make. They are very similar to single-crystalline in performance and degradation, except the cells are typically

slightly less efficient. However, because there is no wasted space between the corners of the cells, when they are

encapsulated in solar PV panels, the performance is almost identical to mono crystalline solar PV panels.


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Poly Crystalline

Light Dependent ResistorThe Photoconductive Cell

A Photoconductive light sensor does not produce electricity but simply changes its physical properties when

subjected to light energy. The most common type of photoconductive device is the Photoresistorwhich changes its

electrical resistance in response to changes in the light intensity. Photoresistors areSemiconductordevices that

use light energy to control the flow of electrons, and hence the current flowing through them. The commonly

used Photoconductive Cellis called the Light Dependent Resistor or LDR.

The Light Dependent Resistor

Typical LDR

As its name implies, the Light Dependent Resistor (LDR) is made from a piece of exposed semiconductor material

such as cadmium sulphide that changes its electrical resistance from several thousand Ohms in the dark to only a

few hundred Ohms when light falls upon it by creating hole-electron pairs in the material. The net effect is an

improvement in its conductivity with a decrease in resistance for an increase in illumination. Also, photoresistive

cells have a long response time requiring many seconds to respond to a change in the light intensity.
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Materials used as the semiconductor substrate include, lead sulphide (PbS), lead

selenide (PbSe), indium antimonide (InSb) which detect light in the infra-red range with

the most commonly used of all photoresistive light sensors being Cadmium

Sulphide (Cds). Cadmium sulphide is used in the manufacture of photoconductive cells

because its spectral response curve closely matches that of the human eye and can even

be controlled using a simple torch as a light source. Typically then, it has a peak

sensitivity wavelength (p) of about 560nm to 600nm in the visible spectral range.

The Light Dependent Resistor Cell

7 Relays:

Basic Relay

A relay is usually an electromechanical device that is actuated by an electrical current. The current flowing in one

circuit causes the opening or closing of another circuit. Relays are like remote control switches and are used in

many applications because of their relative simplicity, long life, and proven high reliability. Relays are used in a

wide variety of applications throughout industry, such as in telephone exchanges, digital computers and

automation systems. Highly sophisticated relays are utilized to protect electric power systems against trouble and

power blackouts as well as to regulate and control the generation and distribution of power. In the home, relays

are used in refrigerators, washing machines and dishwashers, and heating and air-conditioning controls. Although


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relays are generally associated with electrical circuitry, there are many other types, such as pneumatic and hydraulic.

Input may be electrical and output directly mechanical, or vice versa.

7.1 Operating Principle

All relays contain a sensing unit, the electric coil, which is powered by AC or DC current. When the applied current

or voltage exceeds a threshold value, the coil activates the armature, which operates either to close the open contacts

or to open the closed contacts. When a power is supplied to the coil, it generates a magnetic force that actuates the

switch mechanism. The magnetic force is, in effect, relaying the action from one circuit to another.

There are three basic functions of a relay: On/Off Control, Limit Control and Logic Operation.

1] On/Off Control: Example: Air conditioning control, used to limit and control a highpower load, such as a

compressor.

2] Limit Control: Example: Motor Speed Control, used to disconnect a motor if it runs slower or faster than the

desired speed.3] Logic Operation: Example: Test Equipment, used to connect the instrument to a number of testing points on the

device under test.

7.2 Types of Relays:

A] Neutral Relays

This is the most elementary type of relay. The neutral relays have a magnetic coil, which operates the relay at a

specified current, regardless of the polarity of the voltage applied.

B] Biased Relays

Biased relays have a permanent magnet above the armature. The relay operates if the current through the coil

winding establishes a magneto-motive force that opposes the flux by the permanent magnet. If the fluxes are in the

same direction, the relay will not operate, even for a greater current through the coil.

C] Polarized Relays

Like the biased relays, the polarized relays operate only when the current through the coil in one direction. But there

the principle is different. The relay coil has a diode connected in series with it. This blocks the current in the reverse

direction.

The major difference between biased relays and polarized relays is that the former allows the current to pass through

in the reverse direction, but does the not operate the relay and the later blocks the current in reverse direction.

D] Magnetic Stick Relays or Permopolarized Relays


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These relays have a magnetic circuit with high remanence. Two coils, one to operate (pick up) and one to release

(drop) are present. The relay is activated by a current in the operate coil. On the interruption of the current the

armature remains in picked up position by the residual magnetism. The relay is released by a current through the

release coil.

E] Slow Release Relays

These relays have a capacitor connected in parallel to their coil. When the operating current is interrupted the release

of relay is delayed by the stored charge in the capacitor. The relay releases as the capacitor discharges through the

coil.

F] Relays for AC

These are neutral relays and picked up for a.c. current through their coil. These are very fast in action and used onpower circuits of the point motors, where high current flows through the contacts. A normal relay would be slow and

make sparks which in turn may weld the contacts together. All relays have two operating values (voltages), one

pick-up and the other drop away. The pick-up value is higher than the drop away value.

DC MOTORS

DC Motor Working

(1) Current goes through the coil on the stator and the rotating magnetic field is generated.

(2) Being induced by the rotating magnetic field, induced current is generated on the rotor (squirrel cage).

(3) According to the interaction force between current and magnetic field, the squirrel on which the induced current

goes through turns around.


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3.8.1 Types of DC Motors

There are three main types of motors characterized by the connection of the field winding in relation to the armature.

These are :

1] Shunt motors: In this the field winding is connected in parallel with the armature.

2] Series motor: The armature and field windings are connected n series.

3] Compound motor: The two field windings, one of which is connected in parallel with the armature and the other

in series with it.

PROJECT IDEA

A solar cell generates DC electricity from light, which in turn can be used in many applications such as: charging

batteries, powering equipment, etc. They produce currents as long as light shines, and this produced currents can be

stored in a battery and can be used later on in night. The figure below shows the schematic representation of above

sentences.

This solar tracking system will track maximum intensity of light. When there is decrease in intensity of light, this

system automatically changes its direction to get maximum intensity of light.

Here we are using photo sensors to sense the direction of maximum intensity of light. The difference between the

outputs of the sensors is given to the microcontroller unit. Here we are using the microcontroller for tracking and

generating power from sunlight. It will process the input voltage from the comparison circuit and control the

direction in which the motor has to be rotated so that it will receive maximum intensity of light from the sun. The

power generated from this process is then stored battery and is made to charge an emergency light and is made to

glow during night.


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I. WORKING OF THE ASSEMBLYThe solar tracking system turns out to look somewhat as captured in the picture (the pictures does not have solar

panel. mounted on it).Rotation of the two axes is independent on each other. But they are dependent on the

photo sensors signal given to them. So to make dual axis solar tracking system we need to achieve rotation of the

solar panel in two directions viz. circular and in east to west direction.

To cover circular motion we have rotated the entire assembly in circular direction with the help of the wheels

attached below. And to cover east to west direction we have used pulley and belt arrangement. Here the smaller

pulley is driven by the motor depending upon the respective photo sensors effect. This smaller pulley again drives

the bigger pulley with the help of a tightly placed belt over the two pulleys. This enables the motion in the east to

west direction.

Above diagram depicts the flow of the working. When the assembly is turned on by microcontroller the circuit

checks the input from the photo sensors. This is then given for signal conditioning. Signal conditioning circuit drive

motors according to respective sensors signal. Then circuit checks the status of the photo sensors and drive the

motor till solar panel faces the sun directly. As solar panel faces the sun microcontroller switch the circuit off for 14

min to save energy.


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The automatic solar tracking system will include various features to ensure high energy efficiency of the system.

The various features of the system include

Dual-Axis Automatic Tracking

The basic feature of the system includes automatically tracing the Sun. This means that the system will be able to

make the Solar Panel face the Sun automatically with time.

The Sun relatively moves 360 degrees with respect to Earth everyday [8] .This means that the Sun moves 15

degrees every hour, thus we need to ensure that the Solar Panel moves 15 degrees every hour to follow the sun.

Also as we need to ensure the Sun is traced not only in one but both the axes, this is achieved by tracing the Sun in

both the East West and the South North movement of the Sun.

Dead Band Existence

To ensure that the system does not keep oscillating in either East-West or North-South direction a dead-band

existsAs we know the Solar Panel cannot not keep facing the exact centre of the Sun. However the circuit would

keep trying to find the centre and by doing this it would keep oscillating.To ensure that such a thing does not

happen with our project, we have introduced a dead-band. If the solar panel starts facing the sun with a

permissible deviation from the centre of the Sun, the motors would stop moving, thereby ensuring efficiency in

terms of energy consumption.

ON/OFF Timer

As we know the sun moves 15 degrees per hour[7]. Therefore even if the solar panel does not move for a few

minutes the amount of energy lost will not be significant. Thus taking this fact into consideration, the motors will

run for 1 minute every 15 minutes. This means that the maximum deflection of the Solar Panel can be 3.75 degree;

however the run time will reduce to 6.67 % [7]. Thereby saving more energy than it uses.

ALGO


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CRT DIAGRAM

The circuit of the solar tracking system is as shown above. It basically does switching depending upon the signal so

it uses a lot more relays. The change in the resistance of photo sensors is converted into voltage in the first step.

This voltage is given to the op-amp. Op-amp is kept open loop which modifies the signal and gives it relay. Relay do

switching depending upon the input and it drives motor in appropriate direction i.e. clockwise or anticlockwise.

This circuit is same for x and y both the axis.

Black Book 1 Rough'

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