A problem about calculating DLS_irradiance, a bug?

[qiyang77]

As the introduction in tutorial3.ipynb , in Cell 3,
# compute irradiance on the ground using the solar altitude angle
dls_irr = untilted_direct_irr * (percent_diffuse + np.sin(solar_elevation))
The DLS_irr was calculated by "sin" of solar_elevation.
However, in capture.py , line 162
# compute irradiance on the ground using the solar altitude angle
ground_irr = untiltied_direct_irr * (percent_diffuse + np.cos (self.solar_elevation))
The same var was calculated by "cos" of solar_elevation.

This is a bug and which one is correct? Anyone can help me?

[qiyang77]

The results came from running the code in tutorial 3 and “Capture.dls_irradiance()” function in capture.py are totally different.

[poynting]

Good catch. The library code was updated to fix that bug but we missed it in the tutorial. The library code should be the correct implementation.

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On Sat, Sep 8, 2018, 08:58 yellowpuppy ***@***.***> wrote: The results came from running the code in tutorial 3 and “Capture.dls_irradiance()” function in capture.py are totally different. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#19 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AGTc086FGXCyJYpwTdoAUSQZO4cT_S1jks5uY-klgaJpZM4Wf7R6> .

[qiyang77]

Thank you @poynting ,I saw an issue that had been shut down (#11 ).
It is seem like we should use sin(solar_elevation) to correct the direct irradiance
Therefore, the tutorial code should be the correct but the library code maybe wrong.

[ComteDeLooz]

Hi,
The solar elevation is the altitude of the sun above the horizon (= 90° - sun zenith angle). Therefore, I think we should indeed use np.sin(solar_elevation). If not, this means if the sun is just at the horizon (elevation of 0°), it contributes more to the irradiance on the ground (np.cos(0°) = 1) than if the sun is at zenith (np.cos(90°) = 0) which does not seem logic to me. But maybe I am missing something...

[poynting]

Fixed in c1483c4