Photovoltaic Systems Engineering - UM

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Ali Karimpour Mar 2013

Photovoltaic Systems Engineering

Ali KarimpourAssociate Professor

Ferdowsi University of Mashhad

Reference for this lecture:Photovoltaic Systems Engineering Third Edition CRCRoger Messenger, Jerry Ventre

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Lecture 4

The Sun

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Lecture 4

We do not inherit the earth from our ancestors, we borrow it from our children.

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Some Energy Units

Calorie: Heat needed to raise the temperature of 1 ml of water 1 C

Btu: Heat needed to raise the temperature of 1 lb of water 1 F

N-m: The energy expended in raising one kilogram through a distance of one meter.

Ft-lb: The energy expended in raising one pound through a distance of one foot.

Kwh: Energy expended by a kilowatt operating for one hour.

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Some Energy Units

5

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The Solar Spectrum

Energy radiated from the sun

))(

(221

52

mwavelengthmW

e

hcwkThc

)speedLight(sec103)constantsBoltzmann'(/1038.1

)constantsPlanck'(sec1063.6

28

23

234

mcKJk

Wh

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The Solar Spectrum

Irradiance is the power of electromagnetic radiation per unit area incident on a surface.(تابش)

spec

tral i

rrad

ianc

e

27

0/1034.6 mWdwenergyRadiated

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The Solar Energy

27 /1034.6 mWenergyRadiated

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Effect of Atmosphere on Sunlight

14141322 I

20 /1367H Constant Solar mWI

27

0/1034.6 mWdwenergyRadiated

118 105.1,10965.6 DmR

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Amount of Solar Energy

12,756 Km

2/1367 mWI Earth diameter:

Solar energy falling on earth in one hour:

Twh1746094/10127561367 62

MtoeTwh 17000174000

World energy usage in 2008 is around: 12000 Mtoe

10Solar energy falling on earth in one year?

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2/1367 mWI m910393.1diameterSun

m11105.1earth sun to from distanceMean

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2/1367 mWI At AM0:(no air mass)

2/)7.0(1367 mWI At AM1:

2678.0)( /)7.0(1367 mWI AMMeinel:

پرتو

انتشار

انعکاس

Global radiation

Solar Irradiance and Irradiation

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Measuring Solar irradiance

Precision Pyranometer

Black and white Pyranometer

Pyrhelimeter

Pyranometer on shadow band stand

Handheld Pyranometer

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Global

Beamor

direct

Diffuse

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Solar Irradiance and Irradiation

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Solar Irradiation? Peak Sun Hours?

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2/ hourssun peak or n irradiatiosolar daily Average mKwh

The Solar irradiation

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2/ hourssun peak or n irradiatiosolar daily Average mKwh

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Manitoring system

22

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Distance:

mnd

365

)93(360sin017.01105.1 11

Velocity:The Earth orbits the Sun at a speed of 107870 km/h

Sun and Earth Position

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Declination:(میل)

365

)80(360sin45.23 n

Sun and Earth Position

The angle of deviation of the sun from directly above the equator is called declination, .

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Solar time

5.52LSTMIran

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Solar time

5.52LSTMIran

where

city?your in noon today Calculate

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Sun Position

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Latitude and Longitude

The latitude and longitude of Mashhad, Iran is:

36° 17' 44" N / 59° 36' 42" E

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Different Sun Angles

Zenith Angle: The angle between the sun and zenith.Solar Altitude: The vertical angle between the sun and horizon.Azimuth Angle: Horizontal angle between sun and south.

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Different Sun Angles

Hour Angle: Difference between noon and the desired time of day in terms of 360 rotation in 24 hours.

36024

12

T

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Relation Between Sun Angles

365

)80(360sin45.23 dDeclination:

Zenith Angle:

z latitude is

36024

12

T

Hour Angle:

Two Other Useful Relationship:

z coscoscoscossinsinsin

coscossinsinsincos

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36024

12~

T

Hour Angle and :

z coscoscoscossinsinsin

coscossinsinsincos 1

So we have:

coscossinsinsincos

15112 1

~TT

Number of hours of daylight

5.7

tantancos21

0

TDH

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So we have:

coscossinsinsincos

15112 1

~TT

619.3365

)8071(360sin45.23

Declination at 12th March 2013(d=71):

The longitude of Mashhad, Iran is: 3.36

coscossinsinsincos

1511411 1TT

9450 TAstronomical sunrise = 5 52’

Astronomical sunset = 17 30’

455833.0 TActual sunrise = 5 47’

Actual sunset = 17 35’

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So we have:

coscossinsinsincos

15112 1

~TT

619.3365

)8071(360sin45.23

Declination at 12th March 2013(d=71):

The longitude of Mashhad, Iran is: 3.36

coscossinsinsincos

1511411 1TT

Maghreb=17 55’

455833.0 TActual sunrise = 5 47’Actual sunset = 17 35’

4165.4 T

Fajr=4 23’8177.17 T

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An Intersting Example: Direction of Kaaba by seeing sun

826.39,4226.21 :is longitude and Latitude Kabba

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1)cos(coscossinsin0Let z

4226.2113.195221 :is Latitude Kabba

4226.21

time?July 15 196time?May 28 147

n

Direction of Kaaba by seeing sun

30826.39439439:is Longitude Kabba LSTM

)26:11(min34)18:11(min42

July 15 196May 28 147

TCn

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Incidence Angle is the angle between the direction of direct radiation and a line exactly perpendicular to the array angle

Capturing Sunlight

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Tilt angle is the vertical angle between the horizontal and the array surface

Capturing Sunlight

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Array Azimuth Angle is the horizontal angle between a reference direction –typically south- and the direction an array surface faces

Capturing Sunlight

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Capturing Sunlight

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Capturing Sunlight

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Capturing Sunlight

a) Horizontal Array.

b) Array tilted at latitude.

c) Array tilted at latitude -15.

d) Array tilted at latitude +15.

e) b, c, and d but Non-South facing Mounting.

f) 1-Axis tracking array.

g) 2-Axis tracking array.

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Photovoltaic Systems Engineering - UM