solar energy ppt 13

8/10/2019 Solar Energy Ppt 13

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Solar Energy


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The sunis astar

Source of energyinthe sun is at its core

This energy is releasedinto space primarily aselectromagneticradiation

We experience thisradiation as heat andlight

The Sun


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Every hourenough sunlight

energyreaches the earth to meettheworlds energy demandfor awhole year

South Africarepresents the spot ofhighest solar insulation

in the world.South Africahas theperfect climatefor solarenergy

How Powerful is Solar Energy?


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.

Three main uses:

Heatingofwater

Solar thermalpower stations

Photovoltaic panels

Uses for SolarEnergy


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Indirect system: heattransfer fluidmoves heatfrom solar collector to tankDirect solar system:heats waterdirectly

Water in direct systemcirculated in two ways:

Active system: pumpsheated water from collectorto solar storage tankPassive system:no pump- thermosiphon

Two types ofsolar collectors:

- Flat panel- Evacuated Tube system

Solar Water Heating


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Solar Flat Panel

Glass-coveredframework

Inside a series ofcopper tubeswithcopper finsattached

Entire structurecoated inblack substancedesigned to capturethe suns rays

Rays heat water,which circulatesfrom the collector toan isolated tank


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Multiple evacuated glasstubeswith solar absorberscollect heat energy from sun

Absorberinside vacuumtube absorbs radiationfromsunand heats up fluid inside

the copper pipe

Additional radiationispicked up from reflectorbehind tube

Effective whatever theangle of the suneven on acloudy day

Evacuated Tube System


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Used inConcentrated SolarThermal

Power Plants (CSP)

Solar energyisconcentrated toacentral receiver:

a. Parabolic Trough

b. Fresnel

c. Parabolic Dish

d. Central Receiver

ConcentratedSolar Energy

Concentrated Solar Thermal Power Plants


9/13Concentrated Solar Thermal Power Plants

Converting Solar Energy (Heat) into Electricity

A solar thermal

power plantconvertssolar energyintoelectricity

The temperaturein

a concentrated solarpower station is highenough to producesteam

The steamis fedinto a turbine whichgenerates electricity


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Photovoltaic

Effect

Convertingsolar energytoelectrical energybymeans of solar cells =photovoltaic effect

Photovoltaic panelconsists of a groupofsolar cells

Solar cellsarepredominantly madefrom silicon, asemiconductor


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PV panels consist ofsemiconductors

PV cells have two typesof semiconductors:onepositively chargedandone negatively charged

When lightshines onthe semiconductor, theelectric fieldacross the

junctionbetween thesetwo layers causes anelectric current

The greatertheintensityoflight, thegreater the flow ofelectricity.

Converting Solar Energy (Light) into Electricity


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solar energy ppt 13

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