pvlib.irradiance.disc

pvlib.irradiance.disc(ghi, zenith, datetime_or_doy, pressure=101325)[source]

Estimate Direct Normal Irradiance from Global Horizontal Irradiance using the DISC model.

The DISC algorithm converts global horizontal irradiance to direct normal irradiance through empirical relationships between the global and direct clearness indices.

Parameters:

ghi : numeric

Global horizontal irradiance in W/m^2.

solar_zenith : numeric

True (not refraction-corrected) solar zenith angles in decimal degrees.

datetime_or_doy : int, float, array, pd.DatetimeIndex

Day of year or array of days of year e.g. pd.DatetimeIndex.dayofyear, or pd.DatetimeIndex.

pressure : numeric

Site pressure in Pascal.
Returns:

output : OrderedDict or DataFrame

Contains the following keys:

  • dni: The modeled direct normal irradiance in W/m^2 provided by the Direct Insolation Simulation Code (DISC) model.
  • kt: Ratio of global to extraterrestrial irradiance on a horizontal plane.
  • airmass: Airmass

See also

atmosphere.alt2pres, dirint

References

[1] Maxwell, E. L., “A Quasi-Physical Model for Converting Hourly Global Horizontal to Direct Normal Insolation”, Technical Report No. SERI/TR-215-3087, Golden, CO: Solar Energy Research Institute, 1987.

[2] J.W. “Fourier series representation of the position of the sun”. Found at: http://www.mail-archive.com/sundial@uni-koeln.de/msg01050.html on January 12, 2012