pvlib.irradiance.disc¶

pvlib.irradiance.disc(ghi, solar_zenith, datetime_or_doy, pressure=101325, min_cos_zenith=0.065, max_zenith=87)[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.

The pvlib implementation limits the clearness index to 1.

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, default 101325: Site pressure in Pascal.
min_cos_zenith : numeric, default 0.065: Minimum value of cos(zenith) to allow when calculating global clearness index kt. Equivalent to zenith = 86.273 degrees.
max_zenith : numeric, default 87: Maximum value of zenith to allow in DNI calculation. DNI will be set to 0 for times with zenith values greater than max_zenith.

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