.. image:: https://travis-ci.org/SunPower/SolarUtils.svg?branch=master :target: https://travis-ci.org/SunPower/SolarUtils
    SolarUtils is set of Python wrappers around the publicly available
    `NREL <http://www.nrel.gov/>`_
    `SOLPOS <http://rredc.nrel.gov/solar/codesandalgorithms/solpos/>`_ and
    `SPECTRL2 <http://rredc.nrel.gov/solar/models/spectral/>`_ C-language computer
    programs that calculate solar position and spectral decomposition. Please read
    the `NREL disclaimer and license <http://www.nrel.gov/disclaimer.html>`_. Usage
    of this software implies acceptance of the terms.

    Installation
    ============
    Use ``pip`` to install
    `SolarUtils from the PyPI <https://pypi.python.org/pypi/SolarUtils>`_::

        pip install SolarUtils

    You can also download a source distribution from PyPI or clone the repository
    and use Python ``distutils``::

        python setup.py install

    Requirements
    ============
    SolarUtils has no requirements for usage however for installation, testing and
    to build the documentaiton you will need the following pacakges:

    * NumPy
    * PyTest
    * Sphinx

    Usage
    =====
    See `SOLPOS Documentation <http://rredc.nrel.gov/solar/codesandalgorithms/solpos/aboutsolpos.html>`_
    and
    `SPECTRL2 Documentation <http://rredc.nrel.gov/solar/models/spectral/spectrl2/documentation.html>`_
    for more detail.

    Examples
    --------

        >>> from solar_utils import *
        >>> import pandas as pd
        >>> location = [35.56836, -119.2022, -8.0]
        >>> datetime = [2013, 6, 5, 12, 31, 0]
        >>> weather = [1015.62055, 40.0]
        >>> (angles, airmass) = solposAM(location, datetime, weather)
        >>> zenith, azimuth = angles
        >>> zenith
        15.074043273925781
        >>> azimuth
        213.29042053222656]
        >>> am, amp = airmass
        >>> am
        1.0352272987365723
        >>> amp
        1.0379053354263306]

        >>> units = 1
        >>> location = [33.65, -84.43, -5.0]
        >>> datetime = [1999, 7, 22, 9, 45, 37]
        >>> weather = [1006.0, 27.0]
        >>> orientation = [33.65, 135.0]
        >>> atmospheric_conditions = [1.14, 0.65, -1.0, 0.2, 1.36]
        >>> albedo = [0.3, 0.7, 0.8, 1.3, 2.5, 4.0] + ([0.2] * 6)
        >>> specdif, specdir, specetr, specglo, specx = spectrl2(
        ...     units, location, datetime, weather, orientation,
        ...     atmospheric_conditions, albedo
        ... )
        >>> spec = pd.DataFrame(
        ...     {'DIF': specdif, 'DIR': specdir, 'ETR': specetr, 'GLO': specglo},
        ...     index=specx
        ... )
        >>> f = spec.plot()
        >>> f.set_title('Solar Spectrum Example')
        >>> f.set_xlabel('Wavelength, $\lambda [\mu m]$')
        >>> f.set_ylabel('Spectral Irradiance, $I_{\lambda} [W/m^2/\mu m]$')
        >>> f.grid(True)
        >>> f.figure.show()