Photovoltaic Systems Engineering

Transcription

1 Photovoltaic Systems Engineering Ali Karimpour Associate Professor Ferdowsi University of Mashhad Reference for this lecture: Photovoltaic Systems Engineering Third Edition CRC Roger Messenger, Jerry Ventre

2 Lecture 4 The Sun 2

3 Lecture 4 We do not inherit the earth from our ancestors, we borrow it from our children. 3

4 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. 4

5 Some Energy Units 5

6 The Solar Spectrum Energy radiated from the sun w 2hc e 2 hc 1 kt 5 ( m 2 W ( wavelength) ) m h k c W J msec sec / K (Boltzmann's constant) 2 2 (Light (Planck's constant) speed) 6

7 The Solar Spectrum spectral irradiance Irradiance is the power of electromagnetic radiation per unit (تابش). surface area incident on a Radiated energy 0 w d W / m7

8 The Solar Energy Radiated energy W / m 8

9 Effect of Atmosphere on Sunlight Radiated energy 0 w d W / m R m, D Solar Constant H 0 I 1367 W / m 2 I

10 Amount of Solar Energy I 1367 W / m Earth diameter: 12,756 Km Solar energy falling on earth in one hour: Twh Twh / 4 Mtoe World energy usage in 2008 is around: Mtoe Solar energy falling on earth in one year? 10

11 Effect of Atmosphere on Sunlight Sun diameter Mean distance from sun to earth m 11 m I 1367 W / m 2 11

12 Effect of Atmosphere on Sunlight 12

13 Solar Irradiance and Irradiation انتشار Global radiation پرتو انعکاس At AM0: (no air mass) At AM1: I 1367 W / m I 1367(0.7) W / m 2 2 Meinel: I 1367(0.7) W / m ( AM )

14 Measuring Solar irradiance Precision Pyranometer Black and white Pyranometer Global Pyrhelimeter Pyranometer on shadow band stand Handheld Pyranometer Beam or direct Diffuse 14

15 Solar Irradiance and Irradiation Solar Irradiation? Peak Sun Hours? 15

16 The Solar irradiation Average daily solar irradiation or peak sun hours Kwh / m 2 16

17 The Solar irradiation Average daily solar irradiation or peak sun hours Kwh / m 2 17

18 The Solar irradiation 18

19 The Solar irradiation 19

20 The Solar irradiation 20

21 The Solar irradiation 21

22 Manitoring system 22

23 Sun and Earth Position Distance: ( n 93) d sin m 365 Velocity: The Earth orbits the Sun at a speed of km/h23

24 Sun and Earth Position (میل): Declination 360( n 80) 23.45sin 365 The angle of deviation of the sun from directly above the equator is called declination,. 24

25 Solar time Iran LSTM

26 where Solar time lecture 2 Iran LSTM 52.5 Calculate today noon in your city? 26

27 Sun Position 27

28 Latitude and Longitude The latitude and longitude of Mashhad, Iran is: 36 17' 44" N / 59 36' 42" E 28

29 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. 29

30 Different Sun Angles Hour Angle: Difference between noon and the desired time of day in terms of 360 rotation in 24 hours. 12 T

31 Relation Between Sun Angles Declination: Zenith Angle: 360( d 80) 23.45sin 365 Hour Angle: z is latitude 12 T 24 Two Other Useful Relationship: sin 360 sin sin cos cos cos cos sin sin sin cos cos cos z 31

32 Relation Between Sun Angles Hour Angle and : 12 ~ T So we have: sin sin sin cos 1 cos cos Number of hours of daylight sin sin sin cos cos cos cos T ~ 12T 1 15 cos 1 z sin sin sin cos cos DH 2T 0 cos 1 tan tan

33 Relation Between Sun Angles So we have: T ~ 12T Declination at 12 th March 2013 (d=71): 1 15 cos 1 sin sin sin cos cos 360(71 80) 23.45sin The longitude of Mashhad, Iran is: 36.3 T T T sin sin sin cos cos cos Astronomical sunrise = 5 52 Astronomical sunset = T Actual sunrise = 5 47 Actual sunset =

34 Relation Between Sun Angles 34

35 Relation Between Sun Angles So we have: T ~ 12T Declination at 12 th March 2013 (d=71): 1 15 cos 1 sin sin sin cos cos 360(71 80) 23.45sin The longitude of Mashhad, Iran is: 36.3 T T sin sin sin cos cos cos T T Actual sunrise = 5 47 Actual sunset = Maghreb=17 55 T Fajr=

36 An Intersting Example: Direction of Kaaba by seeing sun lecture 2 Kabba Latitude and longitudeis : ,

37 Direction of Kaaba by seeing sun Let z 0 sin sin cos cos cos( ) 1 Kabba Latitude is : n May 15 July time? time? Kabba Longitude is : LSTM 30 n May 15 July TC 42min 34min (11:18) (11: 26) 37

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

39 Capturing Sunlight Tilt angle is the vertical angle between the horizontal and the array surface

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

41 Capturing Sunlight 41

42 Capturing Sunlight 42

43 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. 43