pvl_haydavies1980
Determine diffuse irradiance from the sky on a tilted surface using Hay & Davies' 1980 model.
Contents
Syntax
SkyDiffuse = pvl_haydavies1980(SurfTilt, SurfAz, DHI, DNI, HExtra, SunZen, SunAz)
Description
Hay and Davies' 1980 model determines the sky diffuse irradiance on a tilted surface using the surface tilt angle, surface azimuth angle, diffuse horizontal irradiance, direct normal 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.
- DNI - a scalar or vector of direct normal irradiance in W/m^2. If DNI is a vector it must be of the same size as all other vector inputs. DNI must be >=0.
- HExtra - a scalar or vector of extraterrestrial normal irradiance in W/m^2. If HExtra is a vector it must be of the same size as all other vector inputs. HExtra 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 diffuse component of the solar radiation on an arbitrarily tilted surface defined by the Hay & Davies model [2] as summarized in [1] Equation 7. SkyDiffuse is the sky diffuse component ONLY and does not include the ground reflected diffuse irradiance or 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_haydavies1980(SurfTilt, SurfAz, DHI, DNI, HExtra, SunZen, SunAz)
ans = 68.4462
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] Hay, J.E., Davies, J.A., 1980. Calculations of the solar radiation incident on an inclined surface. In: Hay, J.E., Won, T.K. (Eds.), Proc. of First Canadian Solar Radiation Data Workshop, 59. Ministry of Supply and Services, Canada.
See Also
pvl_perez, pvl_reindl1990, pvl_kingdiffuse, pvl_klucher1979, pvl_grounddiffuse, pvl_ephemeris
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