pvlib.irradiance.reindl

pvlib.irradiance.reindl(surface_tilt, surface_azimuth, dhi, dni, ghi, dni_extra, solar_zenith, solar_azimuth)

Determine diffuse irradiance from the sky on a tilted surface using Reindl’s 1990 model

\[I_{d} = DHI (A R_b + (1 - A) (\frac{1 + \cos\beta}{2}) (1 + \sqrt{\frac{I_{hb}}{I_h}} \sin^3(\beta/2)) )\]

Reindl’s 1990 model determines the diffuse irradiance from the sky (ground reflected irradiance is not included in this algorithm) on a tilted surface using the surface tilt angle, surface azimuth angle, diffuse horizontal irradiance, direct normal irradiance, global horizontal irradiance, extraterrestrial irradiance, sun zenith angle, and sun azimuth angle.

Parameters:

surface_tilt : float or Series.

Surface tilt angles in decimal degrees. The tilt angle is defined as degrees from horizontal (e.g. surface facing up = 0, surface facing horizon = 90)

surface_azimuth : float or Series.

Surface azimuth angles in decimal degrees. The Azimuth convention is defined as degrees east of north (e.g. North = 0, South=180 East = 90, West = 270).

dhi : float or Series.

diffuse horizontal irradiance in W/m^2.

dni : float or Series.

direct normal irradiance in W/m^2.

ghi: float or Series.

Global irradiance in W/m^2.

dni_extra : float or Series.

extraterrestrial normal irradiance in W/m^2.

solar_zenith : float or Series.

apparent (refraction-corrected) zenith angles in decimal degrees.

solar_azimuth : float or Series.

Sun azimuth angles in decimal degrees. The Azimuth convention is defined as degrees east of north (e.g. North = 0, East = 90, West = 270).

Returns:

poa_sky_diffuse : float or Series.

The diffuse component of the solar radiation on an arbitrarily tilted surface defined by the Reindl model as given in Loutzenhiser et. al (2007) equation 8. SkyDiffuse is the diffuse component ONLY and does not include the ground reflected irradiance or the irradiance due to the beam. SkyDiffuse is a column vector vector with a number of elements equal to the input vector(s).

Notes

The poa_sky_diffuse calculation is generated from the Loutzenhiser et al. (2007) paper, equation 8. Note that I have removed the beam and ground reflectance portion of the equation and this generates ONLY the diffuse radiation from the sky and circumsolar, so the form of the equation varies slightly from equation 8.

References

[1] Loutzenhiser P.G. et. al. “Empirical validation of models to compute solar irradiance on inclined surfaces for building energy simulation” 2007, Solar Energy vol. 81. pp. 254-267

[2] Reindl, D.T., Beckmann, W.A., Duffie, J.A., 1990a. Diffuse fraction correlations. Solar Energy 45(1), 1-7.

[3] Reindl, D.T., Beckmann, W.A., Duffie, J.A., 1990b. Evaluation of hourly tilted surface radiation models. Solar Energy 45(1), 9-17.