Interconnectors are transmission lines which allow electricity flows between two separate grid systems (for example to allow the import/export of electricity between two different countries). Thus they provide an important option for balancing supply and demand within a system; for example if it is possible and more economic to import/export electricity than to turn up/down domestic power plants to achieve this balancing. In some markets they are essential in exporting rather than curtailing “excess” power supply – in Denmark for example, where the supply of wind power from their large installed capacity can exceed the in-country demand for power.

Interconnectors are a fundamental requirement in building so-called “supergrids” across large regions, or in enabling power pools (whereby traded electricity markets are extended internationally).