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
See also
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