@property<EOL><INDENT>def S0(self):<DEDENT>
return self._S0<EOL>
Property of solar constant S0.

        The parameter S0 is stored using a python property and can be changed through
        ``self.S0 = newvalue`` which will also update the parameter dictionary.

        .. warning::

            changing ``self.param['S0']`` will not work!

        :getter:    Returns the S0 parameter which is stored in attribute ``self._S0``.
        :setter:    * sets S0 which is addressed as ``self._S0`` to the new value
                    * updates the parameter dictionary ``self.param['S0']`` and
                    * calls method :func:`_compute_fixed`
        :type:      float