2. Solar Energy Resource-1

8/11/2019 2. Solar Energy Resource-1

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SOLAR ENERGYRESOURCE

Mehran Univers i ty o f Engin eer ing andTech no log y, Jam sh oro , Pakis tan


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Solar energy

Solar energy is quite simply the energy produceddirectly by the sun and collected elsewhere,normally the earth.

The sun creates its energy through athermonuclear process that converts about 650million tons of hydrogen into helium every second.

The process creates heat and electromagneticradiation. The heat remains in the sun and isinstrumental in maintaining the thermonuclearreaction.


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Radiant Energy/Solar Energy

The suns energy is created from the fusion ofhydrogen nuclei into helium nuclei.


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Solar energy The electromagnetic radiations (including visible light,infra-red light, and ultraviolet radiation) streams out intospace in all directions.

Only a very small fraction of the total radiation producedreaches the earth.

The radiation that does reach the earth is the indirectsource of nearly every type of energy used today.

The exceptions are geothermal energy, and nuclear fissionand fusion.

Even fossil fuels owe their ori ins to the sun.


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SOLAR ENERGY

In general, the energy produced andradiated by the sun, more specifically theterm refers to the suns energy that reachesthe earth.

Solar energy, received in the form ofradiation, can be converted directly orindirectly into other forms of energy, such asheat and electricity, which can be utilized byman.

Since the sun is expected to radiate at anessentially constant rate for a few billion

years, it may be regarded as an in-exhaustible


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Advantages of Solar Energy

All chemical and radioactive pollutingbyproducts of the thermonuclear reactionsremain behind on the sun, while only pureradiant energy reaches the Earth.

Energy reaching the earth is incredible. Byone calculation, 30 days of sunshine strikingthe Earth have the energy equivalent of the

total of all the planets fossil fuels, both usedand unused!


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Disadvantages of Solar Energy

Sun does not shine consistently (The intermittentand variable manner in which it arrives at the earths surface).

Solar energy is a diffuse source. To harness it, wemust concentrate it into an amount and form thatwe can use, such as heat and electricity. The largearea required to collect the energy at a useful rate.

Addressed by approaching the problem through:1) collection, 2) conversion, 3) storage.


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The sun is large sphere of very hot gases.Its diameter is 1.39 x 10 6 km, while that of the earth is1.27 x 10 4 km.

The mean distance between the two is 1.50 x 10 8 km.

Earth receives approximately 170 million GW of powerfrom the sun, which is a relatively tiny fraction of the suns total output, but is millions of times greater than the

maximum power demand of Earths entire population.


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Solar Energy

Energy is radiated by the sun aselectromagnetic waves of which99% have wave length in the rangeof 0.2 t0 4.0 micrometer.

Solar energy reaching at the top ofearths atmosphere consists of about8% ultraviolet radiation (short wavelength, less than 0.39 ), 46%visible light (0.39 to 0.78 ), and46% infrared radiation (long wavelength more than 0.78 ) .


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Part of the solar radiation reachingthe earths surface is reflected backinto the space specially by clouds.

The radiation entering the

atmosphere is partly absorbed bymolecules in the air.Oxygen and Ozone absorb nearly allthe UV radiation.Water vapor and carbon dioxideabsorb some of the energy in theinfrared range.Part of the solar radiation is scattered(its direction has been changed) bydroplets in clouds by atmosphericmolecules, and by dust particles.

Components of solar radiation


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Solar radiation that has not beenabsorbed or scattered and reaches theground directly from the sun is calleddirect radiation or beam radiation. It isthe radiation which produces a shadowwhen interrupted by an opaque object.

Diffuse radiation is that solar radiationreceived from the sun after its directionhas been changed by reflection andscattering by the atmosphere.

The total solar radiation at any point onthe earths surface is the sum of thedirect and diffuse radiation. This isreferred to in a general sense as the

insolation at that point.

Components of solar radiation


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How much solar energy?

The surface receives about 46% of the total solarenergy that reaches the Earth. Only this amount is

usable.


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Solar irradiance issolar power per unit

area.


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Solar irradiationequals the total solar

irradiance over time.


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A pyranometermeasures total

global solarirradiance from thewhole sky.

Solar Radiation Measurement


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Solar Map of Pakistan


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Argument that sun provides power only during theday is countered by the fact that 70% of energydemand is during daytime hours. At night, traditionalmethods can be used to generate the electricity. Goal is to decrease our dependence on fossil fuels. Currently, 75% of our electrical power is generatedby coal-burning and nuclear power plants. Mitigates the effects of acid rain, carbon dioxide,and other impacts of burning coal and counters risksassociated with nuclear energy. pollution free, indefinitely sustainable.


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The End

2. Solar Energy Resource-1

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