pvlib.irradiance.orgill_hollands#
- pvlib.irradiance.orgill_hollands(ghi, zenith, datetime_or_doy, dni_extra=None, min_cos_zenith=0.065, max_zenith=87)[source]#
Estimate DNI and DHI from GHI using the Orgill and Hollands model.
The Orgill and Hollands model [1] estimates the diffuse fraction DF from global horizontal irradiance through an empirical relationship between hourly DF observations (in Toronto, Canada) and the ratio of GHI to extraterrestrial irradiance, Kt.
- Parameters:
ghi (numeric) – Global horizontal irradiance. [Wm⁻²]
zenith (numeric) – True (not refraction-corrected) 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.
dni_extra (numeric, optional) – Extraterrestrial direct normal irradiance. [W/m2]
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:
data (OrderedDict or DataFrame) – Contains the following keys/columns:
dni: the modeled direct normal irradiance. [Wm⁻²]dhi: the modeled diffuse horizontal irradiance in Wm⁻².kt: Ratio of global to extraterrestrial irradiance on a horizontal plane.
References