def peak_generation_per_technology_and_weather_cell(self):
        """
        Peak generation of each technology and the 
        corresponding weather cell in the grid 

        Returns
        -------
        :pandas:`pandas.Series<series>`
            Peak generation index by technology
        """
        peak_generation = defaultdict(float)
        for gen in self.generators:
            if hasattr(gen, 'weather_cell_id'):
                if (gen.type, gen.weather_cell_id) in peak_generation.keys():
                    peak_generation[gen.type, gen.weather_cell_id] += gen.nominal_capacity
                else:
                    peak_generation[gen.type, gen.weather_cell_id] = gen.nominal_capacity
            else:
                message = 'No weather cell ID found for ' \
                          'generator {}.'.format(repr(gen))
                raise KeyError(message)

        series_index = pd.MultiIndex.from_tuples(list(peak_generation.keys()),
                                                 names=['type', 'weather_cell_id'])

        return pd.Series(peak_generation, index=series_index)
Peak generation of each technology and the 
        corresponding weather cell in the grid 

        Returns
        -------
        :pandas:`pandas.Series<series>`
            Peak generation index by technology