pvlib.solarposition.spa_python¶
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pvlib.solarposition.
spa_python
(time, latitude, longitude, altitude=0, pressure=101325, temperature=12, delta_t=67.0, atmos_refract=None, how='numpy', numthreads=4, **kwargs)[source]¶ Calculate the solar position using a python implementation of the NREL SPA algorithm described in [1].
If numba is installed, the functions can be compiled to machine code and the function can be multithreaded. Without numba, the function evaluates via numpy with a slight performance hit.
Parameters: - time : pandas.DatetimeIndex
Localized or UTC.
- latitude : float
- longitude : float
- altitude : float, default 0
- pressure : int or float, optional, default 101325
avg. yearly air pressure in Pascals.
- temperature : int or float, optional, default 12
avg. yearly air temperature in degrees C.
- delta_t : float, optional, default 67.0
If delta_t is None, uses spa.calculate_deltat using time.year and time.month from pandas.DatetimeIndex. For most simulations specifing delta_t is sufficient. Difference between terrestrial time and UT1. Note: delta_t = None will break code using nrel_numba, this will be fixed in a future version. The USNO has historical and forecasted delta_t [3].
- atmos_refrac : None or float, optional, default None
The approximate atmospheric refraction (in degrees) at sunrise and sunset.
- how : str, optional, default ‘numpy’
Options are ‘numpy’ or ‘numba’. If numba >= 0.17.0 is installed, how=’numba’ will compile the spa functions to machine code and run them multithreaded.
- numthreads : int, optional, default 4
Number of threads to use if how == ‘numba’.
Returns: - DataFrame
The DataFrame will have the following columns: apparent_zenith (degrees), zenith (degrees), apparent_elevation (degrees), elevation (degrees), azimuth (degrees), equation_of_time (minutes).
References
[1] I. Reda and A. Andreas, Solar position algorithm for solar radiation applications. Solar Energy, vol. 76, no. 5, pp. 577-589, 2004.
[2] I. Reda and A. Andreas, Corrigendum to Solar position algorithm for solar radiation applications. Solar Energy, vol. 81, no. 6, p. 838, 2007.
[3] USNO delta T: http://www.usno.navy.mil/USNO/earth-orientation/eo-products/long-term