Solar Miltipurpose Charger and Led Lamp Final Yera Project Report

SOLAR BASED MULTI PURPOSE CHARGER & LED LAMP

MARUDHAR ENGINEERING COLLEGE, BIKANER Page 1

INTRODUCTION TO SOLAR ENERGY [PV CELL]

Non conventional power generation is one of the fastest growing sectors. Globally, all

countries are busy developing and implementing non-conventional power to bridge the

electricity demand and power supply gap. Solar photovoltaic (PV) power is leading ahead of

the other sources. In a solar power generation system, the PV cell plays a major role. The

sun is the ultimate source of limitless solar energy in the form of light and heat. Light of the

sun is directly converted into electrical energy without any inter mediate step. When the rays

of the sun strike certain light-sensitive material like solar cell connected to an appropriate

circuit, it exhibits a phenomenon called µphotovoltaic effect. T he photovoltaic effect is the

generation of an electrical current in a circuit containing a photosensitive device when the

device is illuminated by visible or invisible light. In other words, light is directly converted into

electricity. The photovoltaic effect can be achieved by using a variety of materials like silicon,

selenium, cadmium sulphide, germanium, gallium arsenide or amorphous glass.

PHOTOVOLTAIC CELL

PV cells were invented in 1953 by Charles Fariett. A PV cell is used for converting

photon into electron and with sun light incident, electrical energy is generated. T he

solar-based battery may be used to directly feed electricity to electronic equipment or

for domestic heating. Solar batteries can also be used for satellites, communication

equipment and domestic appliances.

A selenium-or silicon-based solar cell exhibits open-circuit voltage of only 0.5V and short-

circuit cell current of the order of 1milliampere for 6.4cm² area of the cell at 6458

meter candles. Therefore a large number of such silicon or selenium solar cells need to

be connected in series and parallel to provide any significant power. A telemetry system

required to operate 24 hours a day requires a solar panel providing 5 watts at 12 volts used for

recharging corresponding storage batteries during daylight hours.



TYPES OF PHOTOVOLTAIC CELL

At the present time, most commercial photovoltaic cells are manufactured from silicon, the

same material from which sand is made. In this case, however, the silicon is extremely pure.

Other, more exotic materials such as gallium arsenide are just beginning to make their way

into the field. The four general types of silicon photovoltaic cells are:

Single-crystal silicon.

Polycrystal silicon (also known as multi crystal silicon).

Ribbon silicon.

Amorphous silicon (abbreviated as "a Si, " also known as thin film silicon).

Single-crystal silicon

Most photovoltaic cells are single-crystal types. T o make them, silicon is purified, melted, and

crystallized into ingots. The ingots are sliced into thin wafers to make individual cells. The cells

have a uniform color, usually blue or black Typically, most of the cell has a slight positive

electrical charge. A thin layer at the top has a slight negative charge. The cell is attached to a

base called a "backplane." This is usually a layer of metal used to physically reinforce the cell

and to provide an electrical contact at the bottom. Since the top of the cell must be open to

sunlight, a thin grid of metal is applied to the top instead of a continuous layer. The grid must

be thin enough to admit adequate amounts of sunlight, but wide enough to carry adequate

amounts of electrical energy Light, including sunlight, is sometimes described as particles called

"photons." As sunlight strikes a photovoltaic cell, photons move into the cell. When a photon

strikes an electron, it dislodges it, leaving an empty "hole". The loose electron moves toward

the top layer of the cell. As photons continue to enter the cell, electrons continue to be

dislodged and move upwards If an electrical path exists outside the cell between the top grid

and the backplane of the cell, a flow of electrons begins. Loose electrons move out the top of

the cell and into the external electrical circuit. Electrons from further back in the circuit move

up to fill the empty electron holes.



Operation of a Photovoltaic Cell

Most cells produce a voltage of about one-half volt, regardless of the surface area of the cell.

However, the larger the cell, the more current it will produce. Current and voltage are affected

by the resistance of the circuit the cell is in. The amount of available light affects current

production. The temperature of the cell affects its voltage. Knowing the electrical performance

characteristics of a photovoltaic power supply is important, and is covered in the next section.

Polycrystalline silicon

Polycrystalline cells are manufactured and operate in a similar manner. The differ ence is that a

lower cost silicon is used. This usually results in slightly lower efficiency, but polycrystalline cell

manufacturers assert that the cost benefits outweigh the efficiency losses. The surface of

polycrystalline cells has a random pattern of crystal borders instead of the solid color of single

crystal cells

Ribbon silicon

Ribbon-type photovoltaic cells ar e made by growing a ribbon from the molten silicon instead

of an ingot. These cells operate the same as single and polycrystal cells. The anti-reflective

coating used on most ribbon silicon cells gives them a prismatic rainbow appearance.

Amorphous or thin film silicon

The previous three types of silicon used for photovoltaic cells have a distinct crystal structure.

Amor phous silicon has no such structure. Amorphous silicon is sometimes abbreviated "aSi"

and is also called thin film silicon. Amorphous silicon units are made by depositing very thin

layers of vaporized silicon in a vacuum onto a support of glass, plastic, or metal. Amorphous

silicon cells are produced in a variety of colors Since they can be made in sizes up to several

square yards, they are made up in long rectangular "strip cells." These are connected in series

to make up "modules." Modules of all kinds are described Because the layers of silicon allow

some light to pass through, multiple layers can be deposited. The added layers increase the

amount of electr icity the photovoltaic cell can produce. Each layer can be "tuned" to accept a

particular band of light wavelength. T he perfor mance of amorphous silicon cells can drop as

much as 15% upon initial exposure to sunlight. This drop takes around six weeks.

Manufacturers generally publish post-exposure performance data, so if the module has not

been exposed to sunlight, its performance will exceed specifications at first.

T he efficiency of amorphous silicon photovoltaic modules is less than half that of the other

three technologies. T his technology has the potential of being much less expensive to

manufacture than crystalline silicon technology. For this reason, resear ch is currently under



way to improve amorphous silicon perfor mance and manufacturing processes. In 2002, the

highest reported efficiency for thin film solar cells based on CdTe is 18%, which was achieved

by research at Sheffield Hallam University, although this has not been confirmed by an external

test laboratory.

The US national renewable energy research facility NREL achieved an efficiency of 19.9% for

the solar cells based on copper indium gallium selenide thin films, also known as CIGS NREL has

since developed a robot that builds and analyzes the efficiency of thin-film solar cells with the

goal of incr easing the efficiency by testing the cells in different situations. T hese CIGS films

have been grown by physical vapour deposition in a three-stage co- evaporation process. In

this process In, Ga and Se are evaporated in the first step; in the second step it is followed by

Cu and Se co-evaporation and in the last step terminated by In, Ga and Se evaporation again.

Thin film solar has approximately 15% marketshare; the other 85% is crystalline silicon. Most

of the commercial production of thin film solar is CdTe with an efficiency of 11%. Crystalline

Silicon. The highest efficiencies on silicon have been achieved on monocrystalline cells. T he

highest commercial efficiency (22%) is produced by SunPower, which uses expensive, high-

quality silicon wafers. The University of New South Wales has achieved 25% efficiency on

monocrystalline silicon in the lab technology that has been commercialized through its

partnership with Suntech Power. Crystalline silicon devices are approaching the theoretical

limiting efficiency of 29% and achieve an energy payback period of 1-2 years. By far, the most

prevalent bulk material for solar cells is crystalline silicon (abbreviated as a group as c-Si ), also

known as "solar grade silicon". Bulk silicon is separated into multiple categories according to

crystallinity and crystal size in the resulting ingot, ribbon, or wafer.

1.monocrystalline 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 refined silicon.

Hence most c-Si panels have uncovered gaps at the four corners of the cells.

2.Poly- or multicrystalline silicon (poly-Si or mc-Si) : made fr om cast square ingots

large blocks of molten silicon carefully cooled and solidified. Poly-Si cells are less expensive to

produce than single crystal silicon cells, but are less efficient. US DOE data shows that there

were a higher number of multicrystalline sales than monocrystalline silicon sales.

3.Ribbon silicon is a type of multicrystalline silicon: it is formed by drawing flat thin

films from molten silicon and results in a multicrystalline str ucture. These cells have lower

efficiencies than poly-Si, but save on production costs due to a great reduction in silicon waste,

as this approach does not require sawing from ingots.



PHOTOGENERATION OF CHARGE CARRIERS

When a photon hits a piece of silicon, one of three things can happen:

1. the photon can pass straight through the silicon this (generally) happens for lower energy

photons,

2. the photon can reflect off the surface,

3. the photon can be absorbed by the silicon, if the photon energy is higher than the silicon

band gap value. This generates an electron-hole pair and sometimes heat, depending on the

band structure. When a photon is absorbed, its energy is given to an electron in the crystal

lattice. Usually this electron is in the valence band, and is tightly bound in covalent bonds

between neighboring atoms, and hence unable to move far. The energy given to it by the

photon "excites" it into the conduction band, where it is free to move around within the

semiconductor. T he covalent bond that the electron was previously a part of now has one

fewer electron this is known as a hole. The presence of a missing covalent bond allows the

bonded electrons of neighboring atoms to move into the "hole," leaving another hole behind,

and in this way a hole can move through the lattice. Thus, it can be said that photons absorbed

in the semiconductor create mobile electron-hole pairs. A photon need only have greater

energy than that of the band gap in order to excite an electron from the valence band into the

conduction band. However, the solar frequency spectrum approximates a black body spectrum

at ~6000 K, and as such, much of the solar radiation reaching the Earth is composed of photons

with energies greater than the band gap of silicon. These higher energy photons will be

absorbed by the solar cell, but the difference in energy between these photons and the silicon

band gap is converted into heat (via lattice vibrations called phonons) rather than into usable

electrical energy.



THE P-N JUNCTION

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

way, but rather by diffusing an n-type do pant into one side of a p-type wafer (or vice versa).

If a piece of p-type silicon is placed in intimate contact with a piece of n-type silicon, then 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 concentration (p-type side of the junction). When

the electrons diffuse across the p-n junction, they recombine with holes on the p-type side.

The diffusion of carriers does not happen indefinitely, however, because charges build up on

either side of the junction and create an electric field. The electric field creates a diode that

promotes charge flow, known as drift current, that opposes and eventually balances out the

diffusion of electron and holes.

This region where electrons and holes have diffused across the junction is called the depletion

region because it no longer contains any mobile charge carriers. It is also known as the space

charge region



SOLAR BASED MULTI PURPOSE CHARGER AND LED LAMP

CIRCUIT DIAGRAM

SOLAR CELL



INTRODUCTION TO CIRCUIT

A 12 volt 5 Watt solar panel is used as the source of current.

The cells in the panel are made up of semiconductor material which transforms light

energy into electrical energy.

When the sunlight is maximum, the solar module can generate around 16.5 volts at 400

mA. This current is used to charge the battery.

Diode D1 allows current into three regulator ICs to provide regulated voltage to the

load.

IC1 7812 gives 12 volts and 400 mA current to charge a Lead Acid battery.

The battery can be connected to point C and ground.

IC2 7806 gives regulated 6 volts to charge NiCd battery

Resistor R3 restricts the charging current.

IC3 7805 provides regulated 5 volts to charge all types of Mobile phone batteries which

are rated at 3.6 volts.

Resistor R2 restricts charging current to a safer level. Point A can also used to charge

Lithium ion and NiMh batteries.

High value capacitors C1 and C2 act as current buffers so that a short duration

interruption in current flow from the panel will not affect the charging process.

Red LED indicates the charging process.



BLOCK DIAGRAM

SUN LIGHT

SOLAR CELL

CHARGING CIRCUIT IC 7805,

IC 7806, IC 7812

CHARGING BATTERIES: MOBILE BATTERY, NiCd BATTERY, LEAD ACID

BATTERY

FOUR PARALLEL LEDS [LED LAMP] LOAD



MAJOR COMPONENTS OF SOLAR CHARGER

SOLAR PANEL REGULATOR ICS IC1 7812, IC2 7806, IC 78O5

DIODE IN 5204

LEDS 5mm ,12mm

BATTERIES MOBILE BATTERY, NI-CD BATTERY

FEATURES:-

12 V SOLAR CELL OPERATED CIRCUIT

INDICATES INSTANT CHARGING PROCESS

USES RED LED FOR CHARGING POWER OPERATION

VERY COMPECT IN SIZE SUITABLE FOR OUTDOOR APPLICATION

NO SPECIAL CIRCUIT PROTECTION REQUIRED

IN BUILT REGULATOR CIRCUIT WITH USE OF REGULATOR IC



CHARGER PART LIST

1.RESISTORS:-

R1 1KΩ

R2 47R

R3 47R

2.CAPACITORS:-

C1 4700µF

C2 4700µF

3.SEMICONDUCTORS:-

D1 IN5204 DIODE

L1 RED LED

IC1 7812 REG. IC

IC2 7806 REG. IC

IC3 7805 REG. IC

SOLAR MODULE 12 V, 5 WATT

4. BATTRIES:-

MOBILE BATTERY 3.6 VOLT

LEAD ACID BATTERY 12 VOLT

Ni-Cd BATTERY 6 VOLT

5. MISCELLANEOUS:-

WOODEN BOX 24X30X6 cm box

THERMOCOLE FOR PACKING

SWITCH TOGGLE SWITCH

LED LAMP LOAD FOUR 12mm LEDs



INTERNAL BLOCK DIAGRAM OF IC



REGULATOR IC-1 7812

7812 is a voltage regulator integrated circuit. It is a member of 78xx series of fixed linear

voltage regulator ICs. The voltage source in a circuit may have fluctuations and would not give

the fixed voltage output. The voltage regulator IC maintains the output voltage at a constant

value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7812 provide

+12V regulated power supply Capacitors of suitable values can be connected at input and

output pins depending upon the respective voltage levels.

PIN DIAGRAM

PIN DISCRIPTION

PIN NO. FUNCTION NAME

1 Input voltage (10V-28V) input

2 Ground (0 V) ground

3 Regulated output; 12V (11.75V-12.25V) output



REGULATOR IC-2 7806




value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7806 provide

+6V regulated power supply Capacitors of suitable values can be connected at input and output

pins depending upon the respective voltage levels.

PIN DIAGRAM

PIN DISCRIPTION







REGULATOR IC-3 7805




value. The xx in 78xx indicates the fixed output voltage it is designed to provide. 7805 provides

+5V regulated power supply. Capacitors of suitable values can be connected at input and

output pins depending upon the respective voltage levels.

PIN DIAGRAM

PIN DISCRIPTION







SOLAR PANEL

A 12 volt 5 Watt solar panel is used as the source of current. The cells in the panel are made up

of semiconductor material which transforms light energy into electrical energy. When the

sunlight is maximum, the solar module can generate around 16.5 volts at 400 mA. This current

is used to charge the battery.



PROJECT MAKING PROCEDURE

1) Take a wooden box of dimension of 24X30X6 cm

2) Fit the solar panel of rating of 12 volts , 5 watts, with dimension of 16X24 cm to the one side

of the wooden box with the help of glue and thermocol packing as shown in fig.



3) Now take a PCB and mount the all circuit components as shown in circuit diagram and solder

those with jumper wires and fit that circuit to the opposite side of box with thermocol packing.

Here general purpose PCB is used.

4) now connect the load (LED Lamp , Mobile battery, Ni-Cd battery) to the charger circuit.

5) connect the input to the charger with the out put terminals of solar panel as shown in circuit

diagram. Now put the solar panel in sun light area. If red LED glows means that the charger is

working and it is ready to charge the battery.



6) Now the solar panel based charger is ready to use.



PCB DESIGNING

The main purpose of printed circuit board is in the routing of electric current and signals

through a thin copper layer. The copperlayer substitute the basic wired configuration of the

circuit. Thus making the circuit simpler and compact.

The thin copper through which current pass is bounded firmly to an insulating base material

sometimes called as substrate. This base is manufactured with an integral bonded layer of thin

copper foil which has to be etched or other removed to arrive at the predesigned pattern to

suit the circuit connections or whatever other application is needed, thus making the circuit

compact.

From the construction point of view the main attraction of using PCB is its role as the

mechanical support for small components.

Schematic Preparation:

Schematic is a circuit that is drawn either with the help of software or by manually on paper

with standard symbols. If the circuit is big and complicated then multilayer schematic is made.

The schematic is drawn with coloured pen to indicate the different layers, power lines, signal

lines and ground lines.

Artwork Preparation:

After making the schematic on the paper, same is duplicated on copper gladded epoxy sheet i.

e. PCB with the help of HP marker or nail paint or metallic paint. T his circuit is called artwork.

Before going to the next stage, check the whole patter n and cross check against the circuit

diagram.

Etching Process:

This process requires the use of chemicals, acid resistant dishes and a running water supply.

Ferric chloride is maximum used solution, but other enchants such as ammonium persulphate

can be used. Nitric acid can be used but in general it is not used due to poisonous fumes. The

etching bath should be in a glass or enamel dish.

Then ferric chloride is thoroughly dissolved in water to the proportion suggested. There should

be 0.5lt of water for 125gm anhydrous ferric chloride. Now dip the PCB in the solution and wait

till all unused copper gets removed. During the process, the PCB should be stirr ed

continuously.



The board should not be left in a bath for a moment longer than is needed to remove just the

right amount of copper. In spite of there being a resist coating, there is no protection against

etching away through exposed copper edges, this leads to over etching. Have running water

ready and pouring it on the etched board for 5 minutes, so that all ferric chloride can be

removed properly and rinsed, this halt etching immediately.

The reaction that takes place in the solution is given below:

¾2FeCl+ 2HO + 3Cu3CuCl+ 2Fe(OH)3222

Drilling Process:

Now the paint is washed out by the petrol or acetone or nail paint remover. Now the copper

layout on PCB is rubbed with smooth sand paper slowly and lightly such that only the oxide

layer over the copper is removed.

Now the holes are drilled at the respective places, according to component layout as required.

Drilling is one of the operation that call for great care, because most of the holes will be made

with very small drill.

The size of the drill should not be either more than the required or less than the required. If

the hole is large then it will be difficult to solder and a lot of lead will be consumed. If the hole

is small then component will not be inserted easily.

Tinning Process:

After drilling the marked sites the hole are quoted with the layer of tin. This process is called as

tinning. In this process, a wire of tin is melted and is deposited around the whole drilled. This is

done to ease the proce ss of soldering the deposited tin melts and soldering becomes easy and

neat.

Testing the PCB:

PCB is checked for all interconnections through multimeter, whether the tracks are broken or

short at any place, thereby correction is done through soldering.



Assembling of the Unit:

Components are assembled in proper direction and avoid the touching of the components to

one another. Heat sink is to be put wherever required with heat sink compound.

Soldering:

Soldering is the process of joining of metal part with the aid of a molten solder where the

melting temperature is situated below that of a material joined and where by the surface are

wetted without them becoming molten.

The entire solder alloy has a low melting point with the liquid temperature below the melting

point of pure lead in any solder metal lead is mainly used to lower the cost. The wetting

phenomenon depends on tin.

There are various types of solder material available, the one which is commonly used is tin -

lead. It is the mixture of 61.9% tin and 38% lead. It is used for temperature upto 183*C. During

the soldering operation, an auxiliary medium is mostly used to increase the flow properties of

molten solder or to improve the degree of wetting.

Such a medium is called flux. It is used to provi de a liquid cover over the material. It is also

used to dissolve any oxide on the metal surface. They are applied on the tip of the components

to be soldered.

Dc electricity:

Photovoltaic electricity is DC (Direct Current). The current has a polarity, that is, it flows in one

direction. This has an impact on wiring methods and equipment. In photovoltaic systems,

grounding methods must be complete and correct.

Wire color conventions are critical, not only to protect equipment from reverse polarity,

but also to protect service personnel and system users.



LOW VOLTAGE DOES NOT MEAN HARMLESSNESS:

Whenever working on or around photovoltaic systems remember three very important points:

1) Even at low voltages, photovoltaic systems may be able to deliver substantial current. The

amount of available current may be high enough to kill you.

2) Photovoltaic systems can have two power supplies, not just one. Both the batteries and the

modules in a system can deliver current.

3) Small "har mless" shocks can still injure you. For example, an arc created when making

a wiring connection can ignite the hydrogen gas given off by storage batter ies, causing

an explosion. Likewise, a small shock can startle you, resulting in a fall from a ladder.



THE ROAD AHEAD

In future, India will have to depend on renewable energy. The only source available around us

is sunlight, and we can easily convert sunlight energy into electrical energy by using PV cells to

meet our requirement.

Presently, solar systems are developing 2%. By the end of 2012, the growth rate may increase

to 9%. However to extend use of solar power energy to industrial and commercial areas, the

price of PV cells need to be brought down through low-cost manufacturing techniques



CONCLUSIONS

By making the project “SOLAR BASED MULTI PURPOSE BATTERY CHARGER AND LED LAMP” in

minor project for final year I conclude that In this project we put our greatest effort to

understand & explore more & more about the project.

This project has many useful applications in industries also. we try our best to make this project

successful.



BIBLIOGRAPHY

I developed my this project report of “SOLAR BASED MULTI PURPOSE CHARGER AND LED

LAMP” from following books and web sites.

Solar Electricity Engineer ing of Photovoltaic System ,by Lorezo E.

Power Electronics , by Bhimbra P.S

Electronics and Circuits, by Allen Mottershead

Basic Electronics, by Miami A.K

www.electronicsforu.com

www.wikipedia.com

www.atmel.Com

www.electroschematics.com

http://www.electronicsforu.com/

http://www.wikipedia.com/

http://www.atmel.com/

http://www.electroschematics.com/

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Solar Miltipurpose Charger and Led Lamp Final Yera Project Report