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Confusion Regarding Irradiance Calculation
29 Aug 2021 17:42 #10016
by Michel
Replied by Michel on topic Confusion Regarding Irradiance Calculation
Question related to this stream:
Eq. 9.11 in the tech manual calculates the sky diffuse shading factor. It is a function with 4 variables: array tilt ( betas), length of side of the array (B), Distance between arrays ( R) and number of rows. .
frac calculated manually. with tilt= 40 deg, B=4, R=12.5 nrows=16 gives frac= 0.981326 (a constant not function of the irradiance)
frac calculated with the same parameters by SAM shown in 'data table' / 'lifetime hourly data' / "Subarray 1 Self-shading non-linear sky diffuse irradiance factor | (frac)" = 0.951244 ( also constant over the year)
Why is the value calculated by SAM different from the value calculated with Eq. 9.11 ?
frac equation equivalent attached.
Eq. 9.11 in the tech manual calculates the sky diffuse shading factor. It is a function with 4 variables: array tilt ( betas), length of side of the array (B), Distance between arrays ( R) and number of rows. .
frac calculated manually. with tilt= 40 deg, B=4, R=12.5 nrows=16 gives frac= 0.981326 (a constant not function of the irradiance)
frac calculated with the same parameters by SAM shown in 'data table' / 'lifetime hourly data' / "Subarray 1 Self-shading non-linear sky diffuse irradiance factor | (frac)" = 0.951244 ( also constant over the year)
Why is the value calculated by SAM different from the value calculated with Eq. 9.11 ?
frac equation equivalent attached.
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