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

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 (numeric) – 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 (numeric) – 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 (numeric) – diffuse horizontal irradiance in W/m^2.

• dni (numeric) – direct normal irradiance in W/m^2.

• ghi (numeric) – Global irradiance in W/m^2.

• dni_extra (numeric) – Extraterrestrial normal irradiance in W/m^2.

• solar_zenith (numeric) – Apparent (refraction-corrected) zenith angles in decimal degrees.

• solar_azimuth (numeric) – 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 (numeric) – The sky diffuse component of the solar radiation.

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.