pvlib.irradiance.dirint#
- pvlib.irradiance.dirint(ghi, solar_zenith, times, pressure=101325.0, use_delta_kt_prime=True, temp_dew=None, min_cos_zenith=0.065, max_zenith=87)[source]#
Determine DNI from GHI using the DIRINT modification of the DISC model.
Implements the modified DISC model known as “DIRINT” introduced in [1]. DIRINT predicts direct normal irradiance (DNI) from measured global horizontal irradiance (GHI). DIRINT improves upon the DISC model by using time-series GHI data and dew point temperature information. The effectiveness of the DIRINT model improves with each piece of information provided.
The pvlib implementation limits the clearness index to 1.
- Parameters:
ghi (array-like) – Global horizontal irradiance. See ghi. [Wm⁻²]
solar_zenith (array-like) – True (not refraction-corrected) solar zenith angles. See solar_zenith. [°]
times (DatetimeIndex)
pressure (float or array-like, default 101325.0) – Air pressure. See pressure. [Pa]
use_delta_kt_prime (bool, default True) – If True, indicates that the stability index delta_kt_prime is included in the model. The stability index adjusts the estimated DNI in response to dynamics in the time series of GHI. It is recommended that delta_kt_prime is not used if the time between GHI points is 1.5 hours or greater. If use_delta_kt_prime=True, input data must be Series.
temp_dew (float, or array-like, optional) – Surface dew point temperatures, in. Values of
temp_dewmay be numeric or NaN. Any single time period point with a temp_dew=NaN does not have dew point improvements applied. Iftemp_dewis not provided, then dew point improvements are not applied. See temp_dew. [°C]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°. [°]
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:
dni (array-like) – The modeled direct normal irradiance, as provided by the DIRINT model. [Wm⁻²]
Notes
DIRINT model requires time series data (ie. one of the inputs must be a vector of length > 2).
References
