The four transmission system operators in Germany (TenneT, 50Hertz Transmission, Amprion and TransnetBW) look after the secure operation of the infrastructure of the transmission grids, maintain them, build new powerlines, and grant electricity traders/suppliers with non-discriminatory access to these grids. They are supervised by the Bundesnetzagentur (Federal Network Agency), which for example authorises grid expansion and grid-use fees.
Over long distances: the transmission grids
Transmission grids facilitate the transport of electricity over large distances throughout Germany and even across borders – with a minimum of loss, and directly to the areas where the power is consumed. The German high voltage grid is linked to the wider European grid by interconnectors. The total length of the German transmission grids is about 35,000 kilometres. In the case of alternating current (AC), electricity is transmitted with a maximum voltage of 220 kilovolts (kV) or 380 kV; the voltage of the planned new high voltage direct current (DC) transmission lines will be up to 525 kV.
Directly to the consumer: the distribution grids
At the level of the distribution grids the electricity is transmitted at high, medium and low voltage. Lower voltage grids distribute the power to end users. There are a large number of regional and municipal grid operators in this sector.
- High voltage: 60 kV to 220 kV (grid length approx. 77,000 km)
The high-voltage grid is the link to the ultra-high voltage grid (transformers). High-voltage grids distribute the electricity to urban areas or directly to major industrial concerns.
- Medium voltage: 6 kV to 60 kV (grid length approx. 479,000 km)
The medium voltage grid distributes the electricity to regional transformer substations, or directly to large facilities such as hospitals or factories.
- Low voltage: 230 V or 400 V (grid length approx. 1,123,000 km)
The low voltage grid is used for fine distribution of the electricity. The low voltage grid serves private households, small industrial companies, commercial enterprises and office premises.