pvl_klucher1979
Determine sky diffuse irradiance on a tilted surface using Klucher's 1979 model.
Contents
Syntax
SkyDiffuse = pvl_klucher1979(SurfTilt, SurfAz, DHI, GHI, SunZen, SunAz)
Description
Klucher's 1979 model determines the sky diffuse irradiance 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.
Inputs
- SurfTilt - a scalar or vector of surface tilt angles in decimal degrees. If SurfTilt is a vector it must be of the same size as all other vector inputs. SurfTilt must be >=0 and <=180. The tilt angle is defined as degrees from horizontal (e.g. surface facing up = 0, surface facing horizon = 90)
- SurfAz - a scalar or vector of surface azimuth angles in decimal degrees. If SurfAz is a vector it must be of the same size as all other vector inputs. SurfAz must be >=0 and <=360. The azimuth convention is defined as degrees east of north (e.g. North = 0, East = 90, West = 270).
- DHI - a scalar or vector of diffuse horizontal irradiance in W/m^2. If DHI is a vector it must be of the same size as all other vector inputs. DHI must be >=0. Values of DHI which are < GHI will be set to GHI.
- GHI - a scalar or vector of global horizontal irradiance in W/m^2. If GHI is a vector it must be of the same size as all other vector inputs. GHI must be >=0.
- SunZen - a scalar or vector of apparent (refraction-corrected) zenith angles in decimal degrees. If SunZen is a vector it must be of the same size as all other vector inputs. SunZen must be >=0 and <=180.
- SunAz - a scalar or vector of sun azimuth angles in decimal degrees. If SunAz is a vector it must be of the same size as all other vector inputs. SunAz must be >=0 and <=360. The azimuth convention is defined as degrees east of north (e.g. North = 0, East = 90, West = 270).
Outputs
- SkyDiffuse - the sky diffuse irradiatiance on an arbitrarily tilted surface defined by the Klucher model as given in [1] equation 4. SkyDiffuse is the diffuse component ONLY and does not include the ground reflected irradiance or the direct irradiance. SkyDiffuse is a column vector vector with a number of elements equal to the input vector(s).
Example
SurfTilt = 30; SurfAz = 180; DHI = 47; %DNI = 969; GHI = 473; %HExtra = pvl_extraradiation(60); SunZen = 60; SunAz = 161; pvl_klucher1979(SurfTilt, SurfAz, DHI, GHI, SunZen, SunAz)
ans = 64.9622
References
[1] Loutzenhiser P.G. et al., 2007. Empirical validation of models to compute solar irradiance on inclined surfaces for building energy simulation, Solar Energy vol. 81. pp. 254-267.
[2] Klucher, T.M., 1979. Evaluation of models to predict insolation on tilted surfaces. Solar Energy 23 (2), 111–114.
See Also
pvl_perez, pvl_reindl1990, pvl_kingdiffuse, pvl_haydavies1980, pvl_grounddiffuse, pvl_ephemeris
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