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NEED OF SOLAR ENERGYThe energy crisis and oil embargos of the 1970’s made many nations aware of their dependency on controlled non-renewable energy sources .

This formulated the scientists to search for new alternative sources of energy.

Further researches into renewable sources made a path through solar power, wind power and geothermal power.

Solar power generation has emerged as one of the most rapidly growing renewable sources of energy.

Solar power is the conversion of sunlight into electricity .

The methods used for generating electricity through solar power are:

1. Concentrated solar power(CSP)2. Photovoltaic method .

Solar Power

CSP systems use mirrors or lenses to concentrate a large area of sunlight on to a small area.

Electrical power - produced when concentrated light is converted to heat- drives heat engine connected to electric power generator.

Concentrated Solar Power

PHOTO VOLTAICS

The French physicist -Edmond Becquerel - demonstrated photo voltaic activity.

Photovoltaics – a method of generating electrical power – converts solar radiation into direct current electricity.

This is done by using semiconductors

The first solar cell was constructed by Charles Fritts.

Solar cells are devices converts “photons” of light energy directly into electricity.

They function by photovoltaic effect.

Solar Cell

Transparent Adhesive

Encapsulate Anti-reflective

Coating N-Type Silicon P-Type Silicon Back Contact

Structure of Solar Cell :

Silicon – Phosphorus system form a part of solar cell.

Free electrons and holes are generated on both the sides of the junction.

Current is produced due to these holes and electrons.

Photon strikes the solar cell-is absorbed if its energy is greater than band gap value energy.

Electron receives energy and excites into Conduction band from Valence band.

Electric field created in PV cell provides the required voltage to drive electrons to external circuit

Working :

Electrons from n-type and holes from p-type flow towards p and n type materials respectively, when they are sandwiched together inside a PV cell.

An electric field at the junction is formed. It repels electrons – causes electrons to jump

towards surface. Thus electrons are available for electric circuit. With the help of electric field that provides

voltage electrons are driven into the electric circuit.

Thus electrical current is produced.

Solar Panels : A solar panel -

assembly of photovoltaic cells.

A solar panel -collects and utilizes heat energy from the sun.

Multiple cells in integrated group, all oriented in one plane form a “solar thermal module” .

When photons strike the solar panels they convert into electrons of direct current (DC).

These electrons flow out of the panel and into an inverter.

The inverters converts the DC power into AC power.

Solar Arrays : Solar array -a

linked collection of solar panels.

PV arrays use -inverter and convert DC power produced by the module into AC.

It is used to power the house hold appliances and other loads.

PV can be used in variety of applications:

Consumer products Emergency power systemsVaccine and blood storage refrigerators

Aeration system for pondsPower supply for satellites and space vehicles

Applications :

It is in Charanka village in Gujarat.

It is the Asia’s first and largest power park.

It contributes about 2/3rd ‘s of the 900MW of the total power generated in the country.

Gujarat Power Park :

Avoids green-house gasesInfinite free energyDecentralisation of powerSaving eco-systems and livelihood

Their life span is moreEasy installation

Advantages :

It is extremely “expensive”Solar power is inefficientSolar panels are bulkyNeed for a large amount of area.

Disadvantages :

Although there are

disadvantages of using solar

energy many of the

advantages can make this

alternative energy resource

very affective towards helping

the environment and saving

the world.