1、INTERNATIONAL STANDARD IS0 98454 First edition 1992-10-15 Solar energy - Reference solar spectral irradiance at the ground at different receiving conditions - Part 1: Direct normal and hemispherical solar irradiance for air mass I,5 gnergie solaire - Rayonnement solaire spectral de Mkrence au sol so
2、us diffkentes conditions de rkeption - Partie 1: Rayonnernent solaire direct normal et hbmisph thus 1 In - 8 3,0. 80 in t0 3 Application of the spectral data for deriving effective solar lrradiances and solar spectrum weighted quantities 3.1 Spectrally modified total solar lrradlance If R(R) is the
3、wavelength-dependent property of a device (such as responsivity, transmittance, reflectance, absorptance) and I;:,(R) represents the solar spectral irradiance, then I:, the effective total solar irradiance weighted with the spectral property of this device, can be calculated as an integral of the pr
4、oduct of LA) and R(R). Es = R(I)El dR . . . 3.2 Solar spectrum weighted property The mean value R, of the property R(R), which is ef- fective if the total solar spectrum is applied, can in general be calculated by the following equation. . . (2) Since the spectral property and the spectral ir- radia
5、nce are usually known as discrete values, the integration shall be performed as summations so that equations (1) and (2) become, respectively, N E$ = CRQ,)EAI, . . (3) iz I and Rs= N 4 . . . where ,Ii is the wavelength of the fib point out of Ii for which the spectral data are known. The values repr
6、esent the practical limits of the summation. 3.3 Weighted ordinate method The weighted ordinate method is described by the summations indicated in equations (3) and (4) by using the values Ii, AR, and EA. given in table 1. In- terpolation between nearby values of the spectral response, R(R), is ofte
7、n required since the wave- lengths of digitally recorded response curves may differ from those given in table 1. 3.4 Selected ordinate method In the selected ordinate method the solar spectral irradiance is divided into m wavelength intervals, each containing l/m of the total solar irradiance, ho.,
8、and having a centroid wavelength Li. This re- sults in all the products EA,AJi being equal to Eo.,/m, allowing them to bk factored from the summation. Equations (3) and (4) respectively re- duce to the following: i-. I and R, = l/m2 R(E.,) . . . (3) i-l Appropriate values for the centroid wavelength
9、s for 100 and 50 selected ordinates are provided in tables 2 and 3. For devices with relatively smooth spectral responsivity, 50-point selected ordinates are ad- equate. For devices with spectral responses that contain complex structures, the loo-point selected ordinate or weighted ordinate method s
10、hould be used. 4 Valldatlon of accuracy The values of direct normal irradiance presented here are the same as those measured with a 5,8” field-of-view normal incidence pyrheliometer, which allows a small amount of circumsolar (diffuse) radi- ation to be detected. For the type of atmospheric conditio
11、ns modelled here, this circumsolar radiation adds approximately 1 % to the measured direct ir- radiance. NOTE 4 In the spectral region of interest (0.305 0 Itrn to 4.045 0 ,Irn). the BRITE Monte Carlo computer code has not been adequately verified with experimental data. A comparison of the direct n
12、ormal irradiance resulting from this part of IS0 9845 has been compared with other rig- orous codes. The comparison indicates that the various models agree within + 5 o/o in spectral regions where there is significant radiation present. Almost all of the differences in the results of these rigorous
13、codes can be traced to differences in the molecular absorption co- efficients used as input to the codes. IS0 9845-1:1992(E) Single aberrant values (caused by e.g. unsuitable shading methods) shall not be considered for the tables in this part of IS0 9845. - columns 3, 6 and 9: integrated solar-i!ra
14、diance I$ Li in watts per square metre, Wm ; - columns 4, 7 and 10: the fraction I;. of solar ir- radiance in the wavelength range 0 tb 1,. 5 Standard data of direct normal solar irradiance, hemispherical solar irradiance NOTE 5 There is an insignificant amount of radiation reaching the earths surfa
15、ce at wavelengths below 0,3 blrn. See also the plots of solar irradiance in figures on an equator-facing, 37” tilted plane and normalized hemispherical solar irradlance Cl and C.2. Table 2 presents 100 selected ordinates for: Table 1 presents: - direct normal solar spectral irradiance in the direct
16、normal solar spectral irradiance in the spectral range from 0,305 0 pm to 4,045 0 pm in- - wavelength range from 0,305 0 pm to cident on a tilted plane; 4,045 0 pm; - hemispherical solar spectral irradiance, incident on a 37” tilted plane, equator-facing; - normalized solar spectral irradiance (norm
17、alized to solar irradiance of 1 000 W.m *), hemispherical. The values in table 1 relate to AM = I,5 between surface-plane and sun, and a fteld-of-view angle of 5,8” (ground albedo: 0,2). - hemispherical solar spectral irradiance incident on a 37” tilted plane, equator-facing. The values in table 2 r
18、elate to AM = I,5 between surface-plane and sun, and a field-of-view angle of 5,8” (ground albedo: 0.2). The columns in table 2 give the values for the fol- lowing parameters: - column 1: the fraction 11; of solar irradiance in the wavelength range 0 to R,; The columns in table 1 give values for the
19、 following parameters: _ columns 2 and 4: integrated solar irradiance cl Rk in watts per square metre, W,rn- 2; - column 1: wavelength lj in pm; - columns 3 and 5: wavelength L, in micrometres, pm. - columns 2, 5 and 8: mean value of spectral ir- radiance fij in walk per square metre per micronietre, tv.rn *pm- ; Table 3 presents 50 selected ordinates for the same parameters given in table2.
