pvlib.irradiance.louche(ghi, solar_zenith, datetime_or_doy, max_zenith=90)[source]#

Determine DNI and DHI from GHI using the Louche model.

  • ghi (numeric) – Global horizontal irradiance. [W/m^2]

  • solar_zenith (numeric) – True (not refraction-corrected) zenith angles in decimal degrees. Angles must be >=0 and <=90.

  • datetime_or_doy (numeric, pandas.DatetimeIndex) – Day of year or array of days of year e.g. pd.DatetimeIndex.dayofyear, or pd.DatetimeIndex.


data (OrderedDict or DataFrame) – Contains the following keys/columns:

  • dni: the modeled direct normal irradiance in W/m^2.

  • dhi: the modeled diffuse horizontal irradiance in W/m^2.

  • kt: Ratio of global to extraterrestrial irradiance on a horizontal plane.



Louche A, Notton G, Poggi P, Simonnot G. Correlations for direct normal and global horizontal irradiation on a French Mediterranean site. Solar Energy 1991;46:261-6. DOI: 10.1016/0038-092X(91)90072-5