Appendix F: Perez Anisotropic Model Coefficients for Luminous Efficacy and Zenith Luminance Model

TABLE F.1

Efficacy and Zenith Luminance Coefficients for Each Sky Condition Bin

Global Luminous Efficacy Direct Luminous Efficacy

E bin

a1

b1

c1

d1

a1

b1

c1

d1

1

96.63

-0.47

11.50

-9.16

37.20

-4.55

-2.98

117.12

2

107.45

0.79

1.79

-1.19

98.99

-3.46

-1.21

12.38

3

98.73

0.70

4.40

-6.95

109.83

-4.90

-1.71

-8.81

4

92.72

0.56

8.36

-8.31

110.34

-5.84

-1.99

-4.56

5

86.73

0.98

7.10

-10.94

106.36

-3.97

-1.75

-6.16

6

88.34

1.39

6.06

-7.60

107.19

-1.25

-1.51

-26.73

7

78.63

1.47

4.93

-11.37

105.75

0.77

-1.26

-34.44

8

99.65

1.86

-4.46

-3.15

101.18

1.58

-1.10

-8.29

Diffuse Luminous Efficacy

Zenith Luminance Value

E bin

a1

b1

c1

d1

a1

b1

c1

d1

1

97.24

-0.46

12.00

-8.91

40.86

26.77

-29.59

-45.75

2

107.22

1.15

0.59

-3.95

26.58

17.73

58.46

-21.25

3

104.97

2.96

-5.53

-8.77

19.34

2.28

100.00

0.25

4

102.39

5.59

-13.95

-13.90

13.25

-1.39

124.79

15.66

5

100.71

5.94

-22.75

-23.74

14.47

-5.09

160.09

9.13

6

106.42

3.83

-36.15

-28.83

19.76

-3.88

154.61

-19.21

7

141.88

1.90

-53.24

-14.03

28.39

-9.67

151.58

-69.39

8

152.23

0.35

-45.27

-7.98

42.91

-10.62

130.80

-164.08

Source:

Perez, R., P. Ineichen

, R. Seals, J. Michalsky,

and R. Stewart. (1990).

Modeling daylight avail

ability and irradiance components from direct and global irradiance. Solar Energy, Vol. 44, No, 5, pp. 271-289. With permission from Elsevier.

TABLE F.2

Sky Condition Bin and High-Low Boundaries for Bin

£ Bin

£ Low

£ High

1

1.000

1.065

2

1.065

1.230

3

1.230

1.500

4

1.500

1.950

5

1.950

2.800

6

2.800

4.500

7

4.500

6.200

8

6.200

Source: Perez et al. The Development and Verification of the Perez Radiation Model. Contractor Report Sand88- 7030 National Laboratories. http://prod. sandia. gov/ techlib/access-control. cgi/1988/887030.pdf.

£ is the ratio of diffuse/global irradiance.

TABLE F.3

Regression Equations for ai… di Perez Luminance Model Coefficients as Function of Sky Condition BIN Number (= x = 1 to 8)

Подпись: Global

image069 Подпись: -0.056x5 + 1.3253x4 - 11.977x3 + 50.509x2 - 95.86x + 67.608 Подпись: 0.0723x5 - 1.6774x4 + 14.665x3 - 59.211x2 + 105.86x - 68.888

Подпись: DiffuseПодпись:

Подпись: Zenith 2.2944x2 - 20.342x + 58.725 image075 image076 Подпись: 0.1323x5 + 2.6945x4 - 19.092x3 + 56.594x2 - 64.726x + 122.29
image078 Подпись: 0.0068x5 - 0.173x4 + 1.652x3 - 7.2701x2 + 14.359x - 11.548 Подпись: 1.0026x4 - 19.343x3 + 131.86x2 - 378.97x + 382.3

ai bi ci di

Подпись: Source:Data from http://prod. sandia. gov/techlib/access-control. cgi/1988/887030.pdf accessed 27 Oct 2012.

image42

FIGURE 2.2 Thermal (top right) and solid-state photoelectric detector pyranometers including a silicon photovoltaic reference cell (bottom left).

 

image43

FIGURE 2.4 Left to right: Shaded, ventilated thermal pyranometer for diffuse sky irradi – ance; unshaded thermal pyranometer for total hemispherical irradiance; same model shaded thermal pyranometer and thermal pyrheliometer (below pyranometers) mounted on a solar tracker.

 

image44

FIGURE 2.5 Rotating shadow-band radiometer. Rotating band is below silicon photodiode photoelectric pyranometer (just above horizon line).

image45

Wavelength nanometers

FIGURE 2.6 Representative distributions of power as a function of wavelength for solar energy at the top of the atmosphere (extraterrestrial), solar beam radiation, diffuse sky radia­tion, and total radiation on a horizontal surface for clear sky conditions. Bars show regions of energy utilization by conversion systems. Note especially the difference between the global and diffuse horizontal spectra.

image46

FIGURE 2.10 Typical absolute cavity pyrheliometer for reference DNI measurements.

 

image47

FIGURE 6.1 Global hemispherical pyranometers (left, silicon photodiode; right, thermo­pile) measuring plane of array irradiance for photovoltaic performance testing.

 

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