The pysolar - python module.

Today I tested another python module named pysolar with python 2.7 and 3.6.2 versions.
You can read more about this python module here:
Pysolar is a collection of Python libraries for simulating the irradiation of any point on earth by the sun. It includes code for extremely precise ephemeris calculations and more.
Using pip under Windows OS to install this python module:

C:\Python27\Scripts>pip install pysolar
...
Successfully built pysolar
Installing collected packages: pysolar
Successfully installed pysolar-0.7

I try also with python 3.6.2 version:

C:\Python362\Scripts>pip install pysolar
Collecting pysolar
  Using cached pysolar-0.7.tar.gz
Installing collected packages: pysolar
  Running setup.py install for pysolar ... done
Successfully installed pysolar-0.7

Let's start with a simple example to calculate the angle between the sun and a plane tangent to the earth where
you are:

C:\Python362>python.exe
Python 3.6.2 (v3.6.2:5fd33b5, Jul  8 2017, 04:57:36) [MSC v.1900 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from pysolar.solar import *
>>> import datetime
>>> my_data = datetime.datetime.now()
>>> print (my_data)
2017-08-10 18:12:01.997373
>>> get_altitude_fast(47.4616,26.3015,datetime.datetime.now())
-6.393190003993212

Let's try the scattering of light by the atmosphere, though it uses an
atmospheric model based on data taken in the United States:

>>> latitude_deg =47.2741
>>> longitude_deg = 26.185
>>> my_data = datetime.datetime.now()
>>> altitude_deg = get_altitude(latitude_deg, longitude_deg,my_data)
C:\Python362\lib\site-packages\pysolar\time.py:105: UserWarning: I don't know about leap seconds after 2015
  (leap_seconds_base_year + len(leap_seconds_adjustments) - 1)
>>> azimuth_deg = get_azimuth(latitude_deg, longitude_deg,  my_data)
>>> radiation.get_radiation_direct(my_data, altitude_deg)
634.4916522219954

About this issue:I don't know about leap seconds after 2015 read here.