Solar trainer manual

8/10/2019 Solar trainer manual

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Solar Energy Trainer

NV6005

Learning MaterialVer 1.1

Designed & Manufactured by:

141-B, Electronic Complex, Pardesipura, Indore- 452 010 India,Tel.:91-731- 4211500,

Telefax:91-731-4202959,Toll free:1800-103-5050,E-mail:[email protected]

Website:www.nvistech.com
mailto:[email protected]:[email protected]


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NvisTechnologies Pvt. Ltd.

Solar Energy TrainerNV6005

Table of Contents

1. Introduction 3

2. Features 4

3. Technical Specifications 5

4. Theory 6

5. Experiments

Experiment 1

Study of the voltage and current of the solar cells

27

Experiment 2

Study of the voltage and current of the solar cells in series

and parallel combinations

28

Experiment 3

Study of both the currentvoltage characteristic and the power

curve to find the maximum power point (MPP) and efficiency of

a solar cell

32

Experiment 4To calculate the efficiency () of the solar cell

35

Experiment 5

Study of the application of solar cells of charging Ni-Cd battery

so that the loads can be used even while the module is unexposed

to light

37

Experiment 6

Study of the application of solar cells of providing electrical

energy to the domestic appliances such as lamp, fan and radio

39

6. Warranty 41

7. List of Accessories 41
http://www.nvistech.com/


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Introduction

NV6005 Solar Energy Traineris a versatile training system used in the laboratories.

With this system students can understand the various characteristics and applications

of solar energy. They will learn how solar cells are put together to generate the

desired voltage and current and how solar energy can be utilized to operate different

electrical and electronic appliances.

This system is provided with aSolar Energy Trainer andSolar Panel. Solar Panel

contains 6 cells each of 2V DC and 150mA DC rating. Solar Energy Trainer contains

three sections : 1. Solar Input Section 2. Measurement Section 3. Application Section

and are represented in such an easy way so that each section can be studied differently

and so easily. The Solar Cell Input Section contains outputs of all 6 cells.

Measurement Section contains Voltmeter, Ammeter and Potentiometer. Students can

easily measure voltage and current of solar cells themselves using voltmeter and

ammeter provided. Application Section contains charging section and other

appliances that can be operated using solar energy. Charging Section charges the

battery directly by solar energy and provides supply to load through amplifier section.Domestic appliances like lamp, fan and FM radio are provided on board.

Solar Energy Trainer

Figure 1


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Features

o Complete training system to study the fundamentals of Photovoltaic System

o The system has two modes for study Characteristics and Application Modes

o On board voltmeter and ammeter are provided to measure the voltage and

o current respectively, during various modes of operation

o Charging the battery using solar energy

o Weather proof solar cells

o Portable and light weight

o User friendly manual is provided with theoretical and practical details

o 2 Year Warranty


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Technical Specifications

Solar Panel : Consists of 6 solar cells

Maximum Voltage of each solar cell : 2V DC

Maximum Current of each solar cell : 150mA DC

Voltmeter : 0-10V DC

Ammeter : 0-500mA DC

Potentiometer : 5K

Rechargeable Ni-Cd Battery : 1.2V DC

Bulb : 2.2V, 250mA DC

Fan : 1.5V, 400mA DC

FM Band Radio : 12V DC


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Renewable Energies :

Theory

Renewable energies are energy sources that are continuously being replenished bynatural processes that occur on human timescales. In contrast, fossil fuels (coal,

natural gas, oil) require millions of years of geological processes to form. Our

resources of fossil and nuclear fuels (e.g. uranium) are limited. Regenerative energies,

on the other hand, are virtually in exhaustible.

Examples of renewable energy sources include :

Solar energy (Hydrogen fusion in the Sun ) :

Solar energy surrounds us in different forms and can be used in a variety of ways,

including:

Solar radiation : photovoltaic, solar heat Atmospheric

movement : wind energy Evaporation/precipitation :hydroelectric energy/water power Biomass: e.g., fiber fuel,

biogas

Todays most widespread applications for using regenerative energies are solarpanels, wind power plants and hydroelectric power plants.

Tidal energy (Gravitational attraction of Sun, Earth and Moon) :

Tidal power plants use the energy provided by high and low tides. Water is stored

during high tide and released during low tide, powering turbines in the process.

Geothermal energy (Radioactivity and primordial heat in Earths Interior)

Geothermal power plants use heat released from the interior through Earths crust.The heat can be used directly or converted to electricity.

Renewable energy technologies tap into natural cycles and systems, turning the ever-

present energy around us into usable forms. The movement of wind and water, the

heat and light of the sun, heat in the ground, The carbohydrates in plants all are

natural energy sources that can supply our needs in a sustainable way. Because they

are homegrown, renewables can also increase our energy security.

Photovoltaics : From sunlight to electricity :

The wordPhotovoltaicis a combination of the Greek word for Light and the name of

the physicist Allesandro Volta. It identifies the direct conversion of sunlight into

energy by means of solar cells.

Photovoltaic refer to the creation of voltage from light. Solar Photovoltaic System

directly convert sunlight into useful electricity. This process is called photoelectric

effect, discovered by Alexander Bequerel in 1839. The photoelectric effect describes

the release of positive and negative charge carriers in a solid state when light strikes

its surface.

The energy generator in a PV system is the solar cell.


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History of Photovoltaic Cells :

The development of solar cell technology begins with the 1839 research of French

physicist Antoine-Csar Becquerel. Becquerel observed the photovoltaic effect while

experimenting with a solid electrode in an electrolyte solution when he saw a voltagedevelop when light fell upon the electrode.

First Solar Cell :

According to Encyclopedia Britannica the first genuine solar cell was built around

1883 by Charles Fritts, who used junctions formed by coating selenium (a

semiconductor) with an extremely thin layer of gold.

Further Work on Solar Cells :

By 1927 another metal- D semiconductor-junction solar cell, in this case made of

copper and the semiconductor copper oxide, had been demonstrated. By the 1930s

both the selenium cell and the copper oxide cell were being employed in light-

sensitive devices, such as photometers, for use in photography.

Silicon Solar Cell :

These early solar cells, however, had energy conversion efficiencies of less than one

percent. This problem was finally was finally overcome with the development of

silicon solar cell.

In 1941, the American Russell Ohl invented a silicon solar cell.

Efficient Solar Cells :

In 1954, three American researchers, Gerald Pearson, Calvin Fuller and Daryl Chapin,

designed a silicon solar cell capable of a six percent energy conversion efficiency

with direct sunlight.

The three inventors created an array of several strips of silicon (each about the size ofa razorblade), placed them in sunlight, captured the free electrons and turned them

into electrical current. They created the first solar panels. Bell Laboratories in New

York announced the prototype manufacture of a new solar battery. Bell had funded

the research. The first public service trial of the Bell Solar Battery began with a

telephone carrier system (Americus, Georgia) on October 4 1955.

By the late 1980s, silicon cells, as well as those made of gallium arsenide, with

efficiencies of more than 20 percent had been fabricated. In 1989 a concentrator solar

cell, a type of device in which sunlight is concentrated onto the cell surface by means

of lenses, achieved an efficiency of 37 percent due to the increased intensity of the

collected energy. In general, solar cells of widely varying efficiencies and cost are

now available.

Working of Photovoltaic Cells :

Photovoltaic systems convert sunlight directly into electrical energy.

The backbone of this technology is semi-conducting materials such as silicon. A

typical solar cell consists of two differently doped semiconductors. Doping is the

controlled introduction of impurities into the host material. Starting out with a pure


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semiconductor crystal (say, silicon) this is achieved by substituting some of the atoms

in the crystal lattice with elements that have one more or less valence electron than

the host material (valence electrons are the electrons that determine the chemical

behavior of a material, they are located in the outermost orbital shell of the atom).

Semiconducting elements have four valence electrons all of which are used for

bonding in the crystal lattice. If the doping material has five valence electrons there

will be one additional, loosely bound electron per dopant atom. These 'free' atoms can

move about easily in the lattice and are responsible for an increase in conductivity.

Since they have a negative charge the material doped in this way is called as n-type

semiconductor. If, on the other hand, the doping material has only three valence

electrons the lattice structure will be deficient of electrons and there will be one hole,

or positive charge, per dopant atom. Similar to the free electrons above, the holes can

easily move about in the lattice, again causing an increase in conductivity. Since in

this case the free charge carriers are positive this kind of semiconductor is said to be

of p-type.

When a p-type semiconductor is joined to an n-type semiconductor, a p-n junction is

created. While each side by itself is electrically neutral (there are as many electrons as

there are protons) this is not the case for certain areas of the combined configuration.

The concentration differences of holes and free electrons between n- and p- regions

produce diffusion current: electrons flow from the n-side and fill holes on the p-side.

This creates a region that is almost devoid of free charge carriers (i.e. free electrons or

holes) and is therefore called the depletion zone. In the depletion zone there is a net

positive charge on the n-side and a net negative charge on the p-side resulting in an

electric field that opposes a further flow of electrons. The more electrons move from

the n- to the p-side the stronger the opposing field will be and eventually an

equilibrium will be reached in which no further electrons are able to move against the

electric field. The potential difference of the equilibrium electric field is calleddiffusion voltage. It cannot be used externally. However, when light hits the solar cell

the equilibrium conditions are disturbed and the so-called inner photo effect creates

additional charge carriers that are free to move in the electric field of the depletion

zone.

Holes move towards the p-region and electrons towards the n-region, thus creating an

external voltage (no-load voltage) at the cell. The no-load voltage of a solar cell is

material dependent and does not depend on the cell's surface area. A silicon solar cell

has a no-load voltage of about 0.5 V. Higher voltages can be obtained by connecting

individual cells in series.

The current delivered by a solar cell is proportional to the intensity of the incoming

light. Higher currents can be achieved by connecting cells in parallel.The power of a solar cell depends not only on the cell itself but also on the connected

electrical load. The maximum power point (MPP) can easily be determined from the

power-voltage characteristic of the cell.

The efficiency of a solar cell is temperature dependent. It will decrease with

increasing temperature.


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Solar Cell Model :

Basic structure of a silicon PV cell

The thickness of solar cell is approximately 0.33 mm.

The thickness of n-type semiconductor is approximately .002mm.

Figure 2

A. Cover glass :The cover glass, made of glass or other clear material such clear

plastic, seals the cell from the external environment.

B. The Antireflective Coating (AR Coating) : Through a combination of a

favorable refractive index, and thickness, this layer serves to guide light into the

PV Cell. Without this layer, much of the light would bounce off the surface of

the cell.C. Contact Grid :The contact grid is made of a good conductor, such as a metal,

and it serves as a collector of electrons.

D. N-Type Silicon : N-type silicon is created by doping (contaminating) the Si

with compounds that contain one more valance electrons than Si does, such as

with either Phosphorus or Arsenic. Since only four electrons are required to

bond with the four adjacent silicon atoms, the fifth valance electron is available

for conduction.

E. P-Type Silicon : P-type silicon is created by doping with compounds

containing one less valance electrons than Si does, such as with Boron. When

silicon (four valance electrons) is doped with atoms that have one less valance

electrons (three valance electrons), only three electrons are available forbonding with four adjacent silicon atoms, therefore an incomplete bond (hole)

exists which can attract an electron from a nearby atom. Filling one hole creates

another hole in a different Si atom. This movement of holes is available for

conduction.


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F. Back Contact :The back contact, made out of a metal, covers the entire back

surface and acts as a conductor.

The path of the photon :

After a photon makes it's way through the cover glass it encounters the antireflective

layer. The antireflective layer channels the photon into the lower layers of the solar

cell.

Once the photon passes the AR coating, it will either hit the silicon surface or the

contact grid metallization. The metallization, being opaque, lowers the number of

photons reaching the silicon surface. The contact grid must be large enough to collect

electrons yet cover as little of the solar cell's surface, allowing more photons to

penetrate.

Now, a photon causes the photovoltaic effect.

As shown in the diagram below the region in the solar cell where the n-type and p-

type Si layers meet is called the p-n-junction.

Solar Cell Model

Figure 3

So due to the p-n-junction, a built in electric field (about 0.6 to 0.7 volts) is always

present across the (darkened) solar cell.

When photons hit the solar cell, freed electrons (-) attempt to unite with holes on the

p-type layer. The p-n-junction, a one-way road, only allows the electrons to move in

one direction. If we provide an external conductive path, electrons will flow through

this path to their original (p-type) side to unite with holes.

The electron flow provides the current ( I ), and the cell's electric field causes a

voltage ( V ). With both current and voltage, we have power ( P ), which is just the

product of the two. Therefore, when an external load (such as an electric lamp) is

connected between the front and back contacts, electricity flows in the cell, working

for us along the way.


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Ph s

Reaction of Photons on Charge Carriers of n- and p-type

Equivalent circuit of a solar cell :

Figure 4

An ideal and the simplest solar cell model consists of diode and current source

connected parallel. Current source current is directly proportional to the solar

radiation. Diode represents PN junction of a solar cell. Equation of ideal solar cell,

which represents the ideal solar cell model, is:

VD

I = I - I emV

T -1

IPh- Photocurrent (A),

where

IS- Reverse saturation current (A) (aproximately range 10-8/m

2),

VD- Diode voltage (V),

VT- Thermal voltage (see equation below),

VT= 25.7 mV at 25C,

m - diode ideality factor = 1...5 x VT(-) (m = 1 for ideal diode)

Thermal voltage, VTcan be calculated with the following equation:

where

VT=

k.T

q

k - Boltzmann constant = 1.38 x 10-23

J/K,

T - Temperature (K),

q - Charge of electron = 1.6 x 10-19

As


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Ideal Solar Cell Model

Figure 5

In practice no solar cell is ideal, so a shunt resistance and a series resistance

component are added to the model.The consequences of resistances are voltage drop

and parasitic currents.

Real Solar cell model with serial and parallel resistance Rsand Rp

Figure 6

Schematic symbol of a solar cell :

Schematic Representation of a Solar Cell

for use in Circuit Diagrams

Characteristics of a Solar Cell :

Figure 7

The usable voltage from solar cells depends on the semiconductor material. In silicon

it amounts to approximately 0.5 V. Terminal voltage is only weakly dependent on

light radiation, while the current intensity increases with higher luminosity. A 100cm silicon cell, for example, reaches a maximum current intensity of approximately 2

A when radiated by 1000 W/m.


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Current-Voltage Characteristic of a

Silicon Solar Cell

Figure 8

The output (product of electricity and voltage) of a solar cell is temperature

dependent. Higher cell temperatures lead to lower output, and hence to lower

efficiency. The level of efficiency indicates how much of the radiated quantity of light

is converted into useable electrical energy.

Different Solar Cell Types :

One can distinguish three cell types according to the type of crystal: monocrystalline,

polycrystalline and amorphous.

The most common semiconductor material used in solar cells is silicon. A number of

different degrees in lattice alignment are in use:

1 Monocrystalline Silicon(cell efficiency of approx. 14-17%)

2 Polycrystalline Silicon(cell efficiency of approx. 13-15%)

3 Amorphic Silicon(cell efficiency of approx. 5-7%)

To produce a monocrystalline silicon cell, absolutely pure semiconducting material is

necessary. Monocrystalline rods are extracted from melted silicon and then sawed into

thin plates. This production process guarantees a relatively high level of efficiency.

Single-crystal silicon or monocrystalline silicon cell isn't the only material used in PV

cells. Polycrystalline silicon is also used in an attempt to cut manufacturing costs,

although resulting cells aren't as efficient as single crystal silicon.

The production of polycrystalline cells is more cost-efficient. In this process, liquidsilicon is poured into blocks that are subsequently sawed into plates. During

solidification of the material, crystal structures of varying sizes are formed, at whose

borders defects emerge. As a result of this crystal defect, the solar cell is less efficient.

Amorphous silicon, which has no crystalline structure, is also used, again in an

attempt to reduce production costs.


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If a silicon film is deposited on glass or another substrate material, this is a so-called

amorphous or thin layer cell. The layer thickness amounts to less than 1m (thickness

of a human hair: 50-100 m), so the production costs are lower due to the low

material costs. However, the efficiency of amorphous cells is much lower than that of

the other two cell types. Because of this, they are primarily used in low power

equipment (watches, pocket calculators) or as facade elements.

Material Level of efficiency in %

Lab (Research)

Level of efficiency in %

Production

(Commercial)

Monocrystalline Silicon approx. 24 14 to17

Polycrystalline Silicon approx. 18 13 to15

Amorphous Silicon approx. 13 5 to7

Over 95% of all the solar cells produced worldwide are composed of thesemiconductor material Silicon (Si). As the second most abundant element in earths

crust, silicon has the advantage, of being available in sufficient quantities, and

additionally processing the material does not burden the environment.

Other materials used include gallium arsenide, copper indium diselenide and

cadmium telluride. Since different materials have different band gaps, they seem to be

"tuned" to different wavelengths, or photons of different energies. One way efficiency

has been improved is to use two or more layers of different materials with different

band gaps. The higher band gap material is on the surface, absorbing high-energy

photons while allowing lower-energy photons to be absorbed by the lower band gap

material beneath. This technique can result in much higher efficiencies. Such cells,

called multi-junction cells, can have more than one electric field.From the Cell to the Panel :

In order to make the appropriate voltages and outputs available for different

applications, single solar cells are interconnected to form larger units. Cells connected

in series have a higher voltage, while those connected in parallel produce more

electric current. The interconnected solar cells are usually embedded in transparent

Ethyl-Vinyl-Acetate, fitted with an aluminum or stainless steel frame and covered

with transparent glass on the front side.

The typical power ratings of such solar modules are between 10 Wpeak and 100

Wpeak. The characteristic data refer to the standard test conditions of 1000 W/m

solar radiation at a cell temperature of 25 Celsius. The manufacturer's standard

warranty of ten or more years is quite long and shows the high quality standards andlife expectancy of today's products.


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Energy Losses in a Solar Cell :

There are various natural limits of efficiency as follows:

1. The different semiconductor materials or combinations are suited only for

specific spectral ranges. Therefore a specific portion of the radiant energy

cannot be used, because the light quanta (photons) do not have enough energy to

"activate" the charge carriers.

Visible light is only part of the electromagnetic spectrum. Electromagnetic

radiation is not monochromatic -- it is made up of a range of different

wavelengths, and therefore energy levels.

Light can be separated into different wavelengths, and we can see them in the

form of a rainbow. Since the light that hits our cell has photons of a wide range

of energies, it turns out that some of them won't have enough energy to form an

electron-hole pair. They'll simply pass through the cell as if it were transparent.

Still other photons have too much energy. Only a certain amount of energy,

measured in electron volts (eV) and defined by our cell material (about 1.1 eV

for crystalline silicon), is required to knock an electron loose. We call this the

band gap energy of a material.

2. A certain amount of surplus photon energy is transformed into heat rather than

into electrical energy.

If a photon has more energy than the required amount, then the extra energy is

lost (unless a photon has twice the required energy, and can create more than

one electron-hole pair, but this effect is not significant). These two effects alone

account for the loss of around 70 percent of the radiation energy incident on our

cell.

We can't choose a material with a really low band gap, use more of the photons.

Because band gap also determines the strength (voltage) of our electric field,

and if it's too low, then what we make up in extra current (by absorbing morephotons), we lose by having a small voltage. Remember that power is voltage

times current. The optimal band gap, balancing these two effects, is around 1.4

eV for a cell made from a single material.

3. There are optical losses, such as the shadowing of the cell surface through

contact with the glass surface or reflection of incoming rays on the cell surface.

4. Electrons have to flow from one side of the cell to the other through an external

circuit. We can cover the bottom with a metal, allowing for good conduction,

but if we completely cover the top, then photons can't get through the opaque

conductor and we lose all of our current (in some cells, transparent conductors

are used on the top surface, but not in all). If we put contacts only at the sides of

our cell, then the electrons have to travel an extremely long distance (for an

electron) to reach the contacts. Remember, silicon is a semiconductor - it's not

nearly as good as a metal for transporting current. Its internal resistance (called

series resistance) is fairly high, and high resistance means high losses. To


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minimize these losses, our cell is covered by a metallic contact grid that shortens

the distance that electrons have to travel while covering only a small part of the

cell surface. Even so, some photons are blocked by the grid, which can't be too

small or else its own resistance will be too high.

5. Other loss mechanisms are electrical resistance losses in the semiconductor and

the connecting cable. The disrupting influence of material contamination,

surface effects and crystal defects, however, are also significant.

Loss mechanisms such as photons with too little energy are not absorbed, surplus

photon energy is transformed into heat cannot be further improved because of

inherent physical limits imposed by the materials themselves. This leads to a

theoretical maximum level of efficiency, i.e. approximately 24% for crystal silicon.

New Directions :

Surface structuring to reduce reflection loss :

For example, construction of the cell surface in a pyramid structure, so that incominglight hits the surface several times. New material: for example, gallium arsenide

(GaAs), cadmium telluride (CdTe) or copper indium selenide (CuInSe).

Tandem or stacked cells :

In order to be able to use a wide spectrum of radiation, different semiconductor

materials, which are suited for different spectral ranges, will be arranged one on top of

the other.

Concentrator cells :

A higher light intensity will be focused on the solar cells by the use of mirror and lens

systems. This system tracks the sun, always using direct radiation.

MIS Inversion Layer cells :

The inner electrical field are not produced by a p-n junction, but by the junction of a

thin oxide layer to a semiconductor.

Gratzel cells :

Electrochemical liquid cells with titanium dioxide as electrolytes and dye to improve

light absorption.

Applications of solar cells :

The electricity generated by the photoelectric effect can be either used directly or can

be stored in batteries or can directly fed into an electric utilitys grid system. The

energy stored in the battery (in the form of chemical energy) can be used to operateany electrical device. If the device operates on DC, then it can be directly connected

to the output load. If the device operates on AC, then an inverter is required to convert

DC into AC.


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1. Rural Electrification :

The provision of electricity to rural areas derives important social and economic

benefits to remote communities throughout the world. Power supply to remote

houses or villages, electrification of the health care facilities, irrigation andwater supply and treatment are just few examples of such applications.

The potential for PV powered rural applications is enormous. The UN estimates

that two million villages within 20 of the equator have neither grid electricity

nor easy access to fossil fuel. It is also estimated that 80% of all people

worldwide do not have electricity, with a large number of these people living in

climates ideally suited to PV applications. Even in Europe, several hundred

thousand houses in permanent occupation (and yet more holiday homes) do not

have access to grid electricity.

The economics of PV systems compares favorably with the usual alternative

forms of rural electricity supply, grid extension and diesel generators. The

extension and subsequent maintenance of transmission lines over long distancesof often a difficult terrain is expensive, particularly if the loads are relatively

small. Regular fuel supply to diesel generators, on the other hand, often present

problems in rural areas, in addition to the maintenance of the generating

equipment.

2. Water Pumping :

More than 10,000 PV powered water pumps are known to be successfully

operating throughout the world. Solar pumps are used principally for two

applications: village water supply (including livestock watering), and irrigation.

Since villages need a steady supply of water, provision has to be made for water

storage for periods of low insolation. In contrast, crops have variable water

requirements during the year which can often be met by supplying water directlyto produce without the need for a storage tank.

Deep well Solar Pump

Figure 9


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3. Lighting :

In terms of the number of installations, lighting is presently the biggest

application of photovoltaics, with tens of thousands of units installed world-

wide. They are mainly used to provide lighting for domestic or communitybuildings, such as schools or health centers. PV is also being increasingly used

for lighting streets and tunnels, and for security lighting. Solar power is used for

many lighted highway signs, eliminating the need for diesel generators.

4. Domestic Supply :

PV powered Traffic Light System

Figure 10

Stand-alone PV domestic supply systems are commonly encountered in

developing countries and remote locations in industrialized countries. The sizerange varies from 50 Wp to 5 kWp (kilowatt-peak) depending on the existing

standard of living. Typically larger systems are used in remote locations or

island communities of developed countries where household appliances include

refrigeration, washing machine, television and lighting. In developing regions

large systems (5 kWp) are typically found for village supply while small

systems (20-200 Wp) are used for lighting, radio and television in individual

houses.


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5. Health Care :

Solar-powered House

Figure 11

Extensive vaccination programmes are in progress throughout the developing

world in the fight against common diseases. To be effective, these programmes

must provide immunization services to rural areas. All vaccines have to be kept

within a strict temperature range throughout transportation and storage. The

provision of refrigeration for this aim is known as the vaccine cold chain.

Mobile Solar Vaccination Cooler

Professional Applications :Figure 12

For some time, photovoltaic modules have proved to be a good source of power for

high-reliability remote industrial use in inaccessible locations, or where the small

amount of power required is more economically met from a stand-alone PV system

than from mains electricity.


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Some of the most important applications of solar energy are nearly invisible.

Telecommunications, oil companies, and highway safety equipment all rely on solar

power for dependable, constant power, far from any power lines.

Examples of these applications include:

1. Ocean Navigation Aids :

Many lighthouses are now powered by solar cells.

PV-powered Navigation Aid in Saint Lawrence River

2. Telecommunication Systems :

Figure 13

Radio transceivers on mountain tops or telephone boxes in the country can often

be solar powered.

Call Boxes : Roadside call box, are connected with a solar panel. California

standardized on the use of solar power and cellular phones to eliminate the need

for any buried cable connections to these phones. Given the sometimes literally

life-saving nature of these call boxes, dependability is a must.

Telecommunications Installations :When you need a microwave repeater on a

remote mountaintop, the last thing you want to do is run a power line up to it.

For reliable power, many communications repeaters in remote areas use solar.

Siemens Solar alone has shipped over 130 megawatts of modules since its

inception, and the use of solar power is projected to grow at 10-15% per year

from now until the year 2010. This is over three to five times the rate of growth

of the Gross National Product of the United States.


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Solar-powered Telecommunication Tower

3. Remote Monitoring and Control :

Figure 14

Scientific research stations, seismic recording, weather stations, etc. use verylittle power which, in combination with a dependable battery, is provided

reliably by a small PV module.

Solar-powered Weather Station

4. Cathodic Protection :Figure 15

This is a method for shielding metal work from corrosion, for example,

pipelines and other metal structures. A PV system is well suited to this

application since a DC source of power is required in remote locations along the

path of a pipeline.


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Solar-powered Pipeline System

Figure 16Given this growth, solar power will be a much larger part of our lives in future.

Homes could incorporate solar power at the time that they are built, dramaticallyreducing both the cost of buying solar power and the cost of utility bills. New

communications technology may make living in remote areas a practical reality

given the availability of solar power. Mobile uses will undoubtedly increase.

And industrial applications will continue to enjoy the versatility of solar power.

Electric Power Generation in Space :

The energy problem related to spacecraft can be split in two parts. The first major

difficulty is of course to escape from the Earth. The second is to power the spacecraft

once it is in space in the middle of nowhere, or better said in the middle of nothing.

The problem of leaving the Earths surface is usually solved by fuel-powered

launchers like Ariane or by a manned Space Shuttle. The spacecraft is placed as

payload in the launcher. Once it is in orbit around the Earth, the satellite or space

probe is freed. A satellite will then go round the Earth in the chosen orbit while a

space probe will be sent on its path in the solar system. In most cases, the spacecraft

possesses its own engines and a small amount of fuel so that it can be maneuvered if

necessary.

Once in space, the spacecraft (or the space station) must have access to a source of

electricity in order to fulfill its mission. Even the exchange of information between

the spacecraft and the earth uses up energy. The mission would be pointless if the

probe or the satellite could not send images or other forms of data back to Earth.

Electricity will also be needed at one time or another to fire the engines, and to

operate scientific instruments.

In space the issue of providing spacecrafts or space stations with the necessary

electricity to run the equipment on board is usually solved by means of solar panels.

Solar panels convert the light coming from the sun into electricity. The energy

available from the sun is always there but decreases as the probe travels further and

further away from the sun. The amount of electricity produced is proportional to the

surface of the solar panels. Often, the size of the panels is much greater than the size


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of the spacecraft itself. It is not possible to put the spacecraft and its deployed solar

panels in a launcher like Ariane. The panels can only deployed once the spacecraft

has arrived in orbit and leaves the launcher. This of course can be a source of huge

problems if the solar panels get stuck and refuse to deploy. In the case of a manned

mission, the crew might be able to fix the problem. The panels of the space stations

are actually mounted by the crew in space. Most missions, however, are not manned,

and everything must be done automatically. It is therefore particularly important to

devise a method of deploying solar panels that is safe and reliable. Photovoltaic solar

generators have been and will remain the best choice for providing electrical power to

satellites in an orbit around the Earth. Indeed, the use of solar cells on the U.S.

satellite Vanguard I in 1958 demonstrated beyond doubt the first practical application

of photovoltaics. Since then, the satellite power requirements have evolved from few

Watts to several kiloWatts, with arrays approaching 100 kW being planned for a

future space station.

A space solar array must be extremely reliable in the adverse conditions of space

environment. Since it is very expensive to lift every kilogram of weight into the orbit,the space array should also have a high power-to-weight ratio.

PV powered Satellite

Figure 17


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Grid-connected Systems :

1. PV Power Stations :

Two types of grid-connected installations are usually distinguished, centralised

PV power stations, and distributed generation in units located directly at the

customer's premises (PV in buildings).

A PV power station feeds the generated power instantaneously into the utility

distribution network (the 'grid') by means of one or more inverters and

transformers. The first PV power station was built at Hysperia in southern

California in 1982 with nominal power specification 1 MW, using crystalline

silicon modules mounted on a 2 axis tracking system.

PV power stations may be approaching economic viability in locations where

they assist the local grid during periods of peak demand, and obviate the need to

construct a new power station. This is known as peak shaving. It can also be

cheaper to place small PV plants within the transmission system rather than to

upgrade it ('embedded' generation).

2. PV in buildings :

PV Power Station

Figure 18

PV arrays mounted on roof tops or facades offer the possibility of large-scale

power generation in decentralised medium-sized grid-connected units. Studies inGermany, Switzerland and the UK have shown that the roof and facade area

technically suitable for PV installations is large enough to supply the country's

electricity demand. The size envisaged for each decentralised residential PV

system is typically 1- 5kW, with systems up to a hundred kW or so suitable for

commercial and industrial buildings.


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Building with Photovoltaic Faade

Figure 19Manufacturing companies of photovoltaic system have recently introduced

"Sunslates" that can be fitted to existing roofs easily. Photograph of these are shown

below:

Solar Panel Installed on Existing Roofs

Figure 20


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The main advantages of these distributed systems over large PV plants are as follows:

There is no cost in buying the land and preparing the site.

The transmission losses are much lower because the load is on the same site as the

supply.

The value of the PV electricity is also higher because it is equal to the selling price

of the grid electricity which has been replaced, rather that to the cost of generating it.

However, it should also be noted that the price paid by utility companies for

electricity exported from a decentralised source is a fraction of the utility sale price.

The optimum economic benefit is therefore derived by consuming all PV produced

electricity, with direct reduction of the energy imported from the utility. Thus grid

connected PV systems are ideal for loads which vary in proportion to the irradiation.

Typical loads are air-conditioning, refrigeration and pumping. Other significant loads

can be timed to operate when PV power is likely to be available. Examples include

washing machines and clothes dryers which can operate on timing clocksAdvantages of Photovoltaic Power :

1. Photovoltaic solar power is one of the most promising renewable energy sources

in the world. Compared to nonrenewable sources such as coal, gas, oil, and

nuclear, the advantages are clear: it's totally non-polluting, has no moving parts

to break down, and does not require much maintenance. There are no fuel costs

or fuel supply problems.

2. A very important characteristic of photovoltaic power generation is that it does

not require a large scale installation to operate, as different from conventional

power generation stations. Power generators can be installed in a distributed

fashion, on each house or business or school, using area that is already

developed, and allowing individual users to generate their own power, quietlyand safely. The equipment can usually operate unattended.

Rooftop power can be added as more homes or businesses are added to a

community, thereby allowing power generation to keep in step with growing

needs without having to overbuild generation capacity as is often the case with

conventional large scale power systems.

3. When photovoltaic power is compared to other renewable energy sources such

as wind power, water power, and even solar thermal power, there are some

obvious advantages. First, wind and water power rely on turbines to turn

generators to produce electricity. Turbines and generators have moving parts

that can break down, that require maintenance, and are noisy. Even solar thermal

energy needs a turbine or other mechanical device to change the heat energy ofthe sun into mechanical energy for a generator to produce electric power.

Photovoltaic power, by contrast, is generated directly from the sun. PV systems

have no moving parts, require virtually no maintenance, and have cells that last

for decades.


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Objective :

Experiment 1

Study of the voltage and current of the solar cells

Procedure :

1. Take the Solar Energy Trainer NV6005 along with Solar Panel.

2. Place the solar panel in the stand and adjust the panel at an angle of about 45

with the ground. Direct the sunlight straight at the solar panel (angle of 90).

Note :If sunlight is not properly available then any source of light like lamp can

be used.

3. With the DB15 connector connect the Solar Energy Trainer NV6005 with the

Solar Panel. Then wait for 1 minute to avoid errors due to temperature

fluctuations.

4. Measure the voltage (V1) of S1 solar cell by connecting its output acrossvoltmeter with the help of patch cords. Similarly, you can measure the voltages

of other solar cells. Record the voltage of all cells (V1, V2, V3, V4, V5, V6)

respectively in the Observation Table.

5. Measure the current (I1) of S1 solar cell by connecting the ammeter across S1

solar cell with the help of patch cords. Similarly, you can measure the current of

other solar cells. Record the current of all cells (I1, I2, I3, I4, I5, I6) respectively in

the Observation Table.

Observation Table :

S. No. Solar Cell DC Voltage

(V)

DC Current

(mA)

1. S1

2. S2

3. S3

4. S4

5. S5

6. S6


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Objective :

Experiment 2

Study of the voltage and current of the solar cells in series and parallel

combinations

Procedure :


2. Place the Solar Panel in the stand and adjust the panel at an angle of about 45with the ground. Direct the sunlight straight at the solar panel (angle of 90).


be used.

3. With the DB15 connector connect the Solar Energy Trainer NV6005 with the

Solar Panel. Then wait for 1 minute to avoid errors due to temperature

fluctuations.

Series combination of cells :

4. With the patch cords, connect outputs of all cells one by one in series such that

the positive terminal of one connected to the negative terminal of the other as

shown in figure 21.

Solar Cells Connected in Series

Solar cells inseries

boostvoltage

Figure 21

5. Connect the positive and negative terminal of the series combination across the

voltmeter as shown in figure 22. Record the total voltage of the series

combination in the Observation Table given below.

Voltmeter Connected to the Series Combination of Solar Cells

Figure 22


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6. Now connect the positive and negative terminal of the series combination across

the ammeter as shown in figure 23. Record the current of the series combination

in the Observation Table given below.

Ammeter Connected to the Series Combination of Solar Cells

Observation Table :

Figure 23

S. No. Solar Cell Voltage

(V)

Current

(mA)

Voltage of the

seriescombination (V)

Current of the

series

combination

(mA)

1. S1

2. S2

3. S3

4. S4

5. S5

6. S6

Sum of the voltages of all solar cells =VTotal= V1+ V2 +V3+ V4 + V5+ V6 = V

Total voltage of series combination =.V

Hence it is clear that the total voltage of the series combination is equal to the sum of

the voltage of all solar cells.

Total current in series combination =.mA

Hence it is clear that the total current of the series combination is equal to theindividual current of each solar cell.


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30NvisTechnologies Pvt. Ltd.

Parallel combination of cells :

7. Take out all the cords from the trainer.

8. With the patch cords, connect all cells one by one in parallel such that the positive

terminal of one connected to the positive terminal of the other, and also the

negative terminal of one connected to the negative terminal of the other as shown

in figure 24.

Solar Cells Connected in Parallel

Figure 24

9. Connect the positive and negative terminal of the parallel combination across

the voltmeter as shown in figure 25. Record the voltage of the parallel


Voltmeter Connected to the Parallel Combination of Solar Cells

Figure 25

10. Now, connect the positive and negative terminal of the parallel combination

across the ammeter as shown in figure26. Record the total current of the parallel


Ammeter Connected to the Parallel Combination of Solar Cells

Figure 26

Note :To measure current by on board ammeter, do not connect more than 3 solar

cells in parallel. For measuring total current of parallel combination of more than 3

solar cells, arrange a digital multimeter or analog ammeter of 1 Ampere rating in your

laboratory.


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Observation Table :

S. No. Solar Cell Voltage

(V)

Current

(mA)

Voltage of the

parallelcombination

Current of the

parallelcombination

1. S1

2. S2

3. S3

4. S4

5. S5

6. S6

Total voltage of parallel combination =..V

Hence it is clear that the total voltage of the parallel combination is equal to theindividual voltage of each solar cell.

Sum of the current of all solar cells = ITotal= I1+ I2 +I3+ I4 + I5+ I6 = mA

Total current of parallel combination =.mA

Hence it is clear that the total current of the parallel combination is equal to the sum of

the current of all solar cells.

Conclusion :

1. Solar cells in series boost voltage but the current remains the same.

2. Solar cells in parallel boost current rating but the voltage remains same.


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Objective :

Experiment 3

Study of both the currentvoltage characteristic and the power curve to find the

maximum power point (MPP) and efficiency of a solar cell

Procedure :


2. Place the solar panel in the stand and adjust the panel at an angle of about 45with the ground. Direct the sunlight straight at the solar panel (angle of 90).


be used.

3. With the DB15 connector connect the Solar Energy Trainer NV6005 with Solar

Panel. Then wait for 1 minute to avoid errors due to temperature fluctuations.

4. Set the potentiometer to maximum resistance i.e. at fully clockwise position andmeasure and record its resistance into the Observation Table.

5. Connect the solar cell as shown in the following circuit diagram.

Setup for determining characteristics of a solar cell

Figure 27

a. Connect positive terminal of solar cell to P1 terminal of the potentiometer.

b. Connect other end of potentiometer i.e. P2 to positive terminal of ammeter.

c. Connect negative terminal of ammeter to negative terminal of solar cell.

d. Now connect the positive terminal of voltmeter to P1 and negative terminal

of voltmeter to P2.

6. Record the values of corresponding voltage and current into the ObservationTable.

7. Now gradually move the potentiometer in anticlockwise direction so that the

resistance of the potentiometer decreases. Now measure the resistances at

successively smaller values and record the corresponding values of voltages and

current into the Observation Table below.


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Note :Always to measure the resistance of potentiometer at any position, first

remove the patch cords from P1 and P2 and measure resistance by multimeter.

Reconnect these connections again for further measurements.

Observation Table :

S. No. Resistance, R

()

Voltage, V

(Volts)

Current, I

(mA)

Power calculated

P = V. I

(Watts)

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

8. Plot the I- V characteristics from the measurements recorded in the table, to

show how the photoelectric current depends on the photoelectric voltage and to

find maximum power point.

Expected I-V curve is as follows

Current-voltage characteristic of the solar cell

Figure 28


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From V-I characteristics you can easily find the maximum power point (MPP).

Maximum power point (MPP) occurs where the product of voltage and current is

greatest.

9. Plot the curve of power as a function of voltage from the measurements

recorded in the table.

Expected Power-Voltage curve is as follows

Power curve of the solar cell as a function of voltage

Figure 29

The maximum power point (MPP) is the maximum value of power in the above

curve.

The resistance, RMPP, at which the output power is at a maximum can be calculated

using the following formula:


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Objective :

Experiment 4

To calculate the efficiency () of solar cell

Theory :

The efficiency of the solar cell is the ratio of produced electrical power (Pout) and the

incident radiant power (Pin).

Efficiency of solar cell, = P

out

Pin

Where Poutis the electrical power (maximum power point)

Pin is calculated by multiplying approximated irradiance (irradiance means

radiant power of the light incident per unit area) by the effective area of the

solar cell on the panel.

This method used the fact that the practical value of the current (maximumphotoelectric current measured) is proportional to the photons (radiation) striking the

solar cell. This current is therefore proportional to the incident radiant power of the

light.

The open circuit voltage depends on the semiconductor material of which solar cell is

made. It is not proportional to the incident radiant power and therefore cannot be used

for this measurement.

Procedure :

1. Efficiency of solar cell,

=

Pout

Pin

Where Pout(Output Electrical Power) = Maximum Power Point (MPP)

Pin(Incident radiant power) = Approximated Irradiance x Area of solar cell

= (F x Ip) x A .....(eq.1)

Here A = Area of a solar cell (Length x Breadth) m2

Ip= Practical value of current (maximum photoelectric current measured)

indicated on the ammeter

F is a constant and is given by

The maximum irradiance in summer is approx. 1000 W/m2. The maximum value of

the current specified by the manufacturer is achieved at this value i.e. 150mA in the

given solar cells. (The parameters of the solar cell/panel is related to the standard test


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conditions of 1000W/m2

and cell temperature of 25 C.)

2. Multiplying the practical value of current (Ip) indicated on the ammeter by the

factor gives an approximation of the radiant power per unit area (irradiance)

striking the solar cell.

Approximation of the radiant power per unit area =.

3. Now measure the area in m2 and put the values in the formula given in eq. 1.

Pin=

Now, we can calculate the efficiency of solar cell with

= P

out

Pin

where Poutor MPP =.. (As calculated in the experiment 3)

=..

The efficiencies of solar cells lie between 12 to 15 %.

If efficiency is slightly less than determined value then it is due to measuring errorsand inaccuracies in determining the incident radiant power. Furthermore, the

efficiency of solar panel is less than that of their separate constituent cells. This is

caused by losses that arise in matching solar cells that do not all have exactly the same

properties. If the solar cells are connected in series to generate desired voltage, the

maximum power point may not be same for all cells.

Solar cell losses arise as not all photons striking the solar cell can be converted into

charge carriers. Part of the light is reflected as soon as it hits the surface and the metal

contacts cast shadows. Since the photon energy does not correspond to the energy

gap, less than half of the incident energy is used. Recombination of charge carriers

(atomic rebinding of electrons) and electrical losses caused by internal resistances

(ohmic losses in the semiconductor) of the solar cell and its contacts also arise.


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Objective :

Experiment 5

Study of the application of solar cells of charging the Ni-Cd battery so that the

loads can be used even while the module is unexposed to light

Procedure :




be used.


Panel NV6005. Then wait for 1 minute to avoid errors due to temperature

fluctuations.

4. Connect rechargeable Ni-Cd Battery in the holder provided in Charging Section.

Battery needs voltage of 1.5-2 V for standard charging at 80mA about 15 hours.

Some batteries are provided with facility of quick charging at 210mA about 3-4

hrs. So connect the solar cells in series or parallel combination as per the

required rating.

5. Now with the help of patch cords, connect the positive terminal of the solar cell

to the positive terminal of diode and negative terminal of solar cell to negative

terminal of battery Section.

6. Now connect the terminal T1 to positive terminal of battery.

7. Connect the voltmeter across battery terminals with patch cord. You can observethe voltage variations.

8. Now to operate the load connect the positive terminal of battery to terminal T2

of amplifier section and T3 to positive terminal of Load with patch cords. Now

connect negative terminal of battery to negative terminal of Load with patch

cord.

9. Observe that the group of LED glows. Here load is operating with the solar

energy and battery is charging with the solar energy.


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For direct operation of load with charged batteries i.e. when module is

unexposed to light :

1. Remove the connections of the solar cells to Charging Section.

2. The charged nickel cadmium battery provides electricity to the load even the

panel is unexposed to light and when battery will discharged then you can

reconnect previous connections for charging the battery.


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Objective :

Experiment 6

Study of the application of solar cells of providing electrical energy to the

domestic appliances such as lamp, fan and radio

Procedure for Lamp :




be used.


Panel NV6005. Then wait for 1 minute to avoid errors due to temperature

fluctuations.

4. Measure the voltage and current of the solar cells and connect the number of

solar cells in parallel as per the desired voltage of around 2.2V and 250mA of

current rating for lamp.

5. Now connect the positive and negative terminals of solar cellss parallel

combination across the lamp with patch cords. Observe that the lamp is glowing

with solar energy.

6. Perform a comparative study between intensity of the lamp and recommended

voltage/current rating.

7. If you insert any obstacle in between sunlight and solar panel you can see the

effect of change of intensity of the lamp. If you insert a fully opaque obstacle

then lamp will stop glowing and when you remove the obstacle lamp will againstart glowing.

Procedure for Fan :

1. Repeat steps 1 to 3 from procedure for lamp.


solar cells in parallel as per the desired voltage of around 1.5V and 400mA of

current rating for fan.

3. Now connect the positive and negative terminals of solar cellss parallel

combination across the fan with patch cords. Observe that the fan is rotating

with solar energy.

Note :Clockwise or anticlockwise rotation of fan depends on polarity of solar

cell inserted across fan terminals.

4. Perform a comparative study between speed of fan and recommended

voltage/current rating.


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change in speed of the fan. If you insert a fully opaque obstacle then fan will

stop rotating and when you remove the obstacle fan will again start rotating.

Procedure for FM Receiver :

1. Repeat steps 1 to 3 from procedure for lamp.


solar cells in series as per the desired voltage of around 5V-6V minimum to 12V

maximum.

3. Set the Volume Control knob to full clockwise rotation for maximum volume

and adjust the Frequency Selector knob to tune any FM Radio Station.

4. Now with the help of patch cords, connect the positive and negative terminals of

solar cells series combination to the positive and negative terminals of FM

Receiver respectively. Observe that the radio is working with solar energy.

5. Perform a comparative study between volume of FM Receiver and

recommended voltage/current rating.


change in volume of the FM Receiver. If you insert a fully opaque obstacle then

FM Receiver will stop working and when you remove the obstacle, FM

Receiver will again start working.


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Warranty

1) We guarantee the product against all manufacturing defects for 24 months from

the date of sale by us or through our dealers. Consumables like dry cell etc. are

not covered under warranty.

2) The guarantee will become void, if

a) The product is not operated as per the instruction given in the l earningmanual.

b) The agreed payment terms and other conditions of sale are not followed.

c) The customer resells the instrument to another party.

d) Any attempt is made to service and modify the instrument.

3) The non-working of the product is to be communicated to us immediately giving

full details of the complaints and defects noticed specifically mentioning the

type, serial number of the product and date of purchase etc.

4) The repair work will be carried out, provided the product is dispatched securely

packed and insured. The transportation charges shall be borne by the customer.

List of Accessories

1. Solar Panel .................................................................................................1 No.

2. Panel Stand with Stand ...............................................................................1 No.

3. 15 Pin Cable (5 Meter) ..............................................................................1 No.

4. 12Patch Cord (2 mm)........................................................................... 15 Nos.

5. Rechargeable Battery .................................................................................1 No.

6. FanBlade................................................................................................1 No.

7. Learning Material CD..................................................................................1 No.

Solar trainer manual

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