Uses the :func:`irradiance.get_total_irradiance` function to
        calculate the plane of array irradiance components on a tilted
        surface defined by the input data and ``self.albedo``.

        For a given set of solar zenith and azimuth angles, the
        surface tilt and azimuth parameters are typically determined
        by :py:meth:`~SingleAxisTracker.singleaxis`.

        Parameters
        ----------
        surface_tilt : numeric
            Panel tilt from horizontal.
        surface_azimuth : numeric
            Panel azimuth from north
        solar_zenith : numeric
            Solar zenith angle.
        solar_azimuth : numeric
            Solar azimuth angle.
        dni : float or Series
            Direct Normal Irradiance
        ghi : float or Series
            Global horizontal irradiance
        dhi : float or Series
            Diffuse horizontal irradiance
        dni_extra : float or Series, default None
            Extraterrestrial direct normal irradiance
        airmass : float or Series, default None
            Airmass
        model : String, default 'haydavies'
            Irradiance model.

        **kwargs
            Passed to :func:`irradiance.total_irrad`.

        Returns
        -------
        poa_irradiance : DataFrame
            Column names are: ``total, beam, sky, ground``.

def get_irradiance(self, surface_tilt, surface_azimuth,
                       solar_zenith, solar_azimuth, dni, ghi, dhi,
                       dni_extra=None, airmass=None, model='haydavies',
                       **kwargs):
        """
        Uses the :func:`irradiance.get_total_irradiance` function to
        calculate the plane of array irradiance components on a tilted
        surface defined by the input data and ``self.albedo``.

        For a given set of solar zenith and azimuth angles, the
        surface tilt and azimuth parameters are typically determined
        by :py:meth:`~SingleAxisTracker.singleaxis`.

        Parameters
        ----------
        surface_tilt : numeric
            Panel tilt from horizontal.
        surface_azimuth : numeric
            Panel azimuth from north
        solar_zenith : numeric
            Solar zenith angle.
        solar_azimuth : numeric
            Solar azimuth angle.
        dni : float or Series
            Direct Normal Irradiance
        ghi : float or Series
            Global horizontal irradiance
        dhi : float or Series
            Diffuse horizontal irradiance
        dni_extra : float or Series, default None
            Extraterrestrial direct normal irradiance
        airmass : float or Series, default None
            Airmass
        model : String, default 'haydavies'
            Irradiance model.

        **kwargs
            Passed to :func:`irradiance.total_irrad`.

        Returns
        -------
        poa_irradiance : DataFrame
            Column names are: ``total, beam, sky, ground``.
        """

        # not needed for all models, but this is easier
        if dni_extra is None:
            dni_extra = irradiance.get_extra_radiation(solar_zenith.index)

        if airmass is None:
            airmass = atmosphere.get_relative_airmass(solar_zenith)

        return irradiance.get_total_irradiance(surface_tilt,
                                               surface_azimuth,
                                               solar_zenith,
                                               solar_azimuth,
                                               dni, ghi, dhi,
                                               dni_extra=dni_extra,
                                               airmass=airmass,
                                               model=model,
                                               albedo=self.albedo,
                                               **kwargs)