docs: def export_to_pypsa(self, session, method='onthefly'):
          """Exports MVGridDing0 grid to PyPSA database tables
  
          Peculiarities of MV grids are implemented here. Derive general export
          method from this and adapt to needs of LVGridDing0
  
          Parameters
          ----------
          session: :sqlalchemy:`SQLAlchemy session object<orm/session_basics.html>`
              Description
          method: str
              Specify export method::
              
              'db': grid data will be exported to database
              'onthefly': grid data will be passed to PyPSA directly (default)
  
          Notes
          -----
          It has to be proven that this method works for LV grids as well!
  
          Ding0 treats two stationary case of powerflow:
          1) Full load: We assume no generation and loads to be set to peak load
          2) Generation worst case:
          """
  
          # definitions for temp_resolution table
          temp_id = 1
          timesteps = 2
          start_time = datetime(1970, 1, 1, 00, 00, 0)
          resolution = 'H'
  
          nodes = self._graph.nodes()
  
          edges = [edge for edge in list(self.graph_edges())
                   if (edge['adj_nodes'][0] in nodes and not isinstance(
                  edge['adj_nodes'][0], LVLoadAreaCentreDing0))
                   and (edge['adj_nodes'][1] in nodes and not isinstance(
                  edge['adj_nodes'][1], LVLoadAreaCentreDing0))]
  
          if method == 'db':
  
              # Export node objects: Busses, Loads, Generators
              pypsa_io.export_nodes(self,
                                    session,
                                    nodes,
                                    temp_id,
                                    lv_transformer=False)
  
              # Export edges
              pypsa_io.export_edges(self, session, edges)
  
              # Create table about temporal coverage of PF analysis
              pypsa_io.create_temp_resolution_table(session,
                                                    timesteps=timesteps,
                                                    resolution=resolution,
                                                    start_time=start_time)
          elif method == 'onthefly':
  
              nodes_dict, components_data = pypsa_io.nodes_to_dict_of_dataframes(
                  self,
                  nodes,
                  lv_transformer=False)
              edges_dict = pypsa_io.edges_to_dict_of_dataframes(self, edges)
              components = tools.merge_two_dicts(nodes_dict, edges_dict)
  
              return components, components_data
          else:
              raise ValueError('Sorry, this export method does not exist!')