pvlib.iam.schlick_diffuse#

pvlib.iam.schlick_diffuse(surface_tilt)[source]#

Determine the incidence angle modifiers (IAM) for diffuse sky and ground-reflected irradiance on a tilted surface using the Schlick incident angle model.

The diffuse iam values are calculated using an analytical integration of the Schlick equation 1 over the portion of an isotropic sky and isotropic foreground that is visible from the tilted surface 2.

Parameters

surface_tilt (numeric) – Surface tilt angle measured from horizontal (e.g. surface facing up = 0, surface facing horizon = 90). [degrees]

Returns

iam_sky (numeric) – The incident angle modifier for sky diffuse.
iam_ground (numeric) – The incident angle modifier for ground-reflected diffuse.

References

1: Schlick, C. An inexpensive BRDF model for physically-based rendering. Computer graphics forum 13 (1994).
2: Xie, Y., M. Sengupta, A. Habte, A. Andreas, “The ‘Fresnel Equations’ for Diffuse radiation on Inclined photovoltaic Surfaces (FEDIS)”, Renewable and Sustainable Energy Reviews, vol. 161, 112362. June 2022. DOI: 10.1016/j.rser.2022.112362