For the expansion of the extra high voltage grid, transmission system operators are subject to legal conditions.
1. The European Internal Electricity Market Directive stipulates that transmission system operators must construct the grid such that unfettered trade in electricity, free grid access for all electricity producers and non-discriminatory grid use are guaranteed at all times. This means the transmission system operators must, as a matter of principle, provide sufficient transport capacity for all electricity producers.
2. In accordance with the German Energy Industry Act (EnWG), the transmission system operators are obliged to operate, maintain, and expand in accordance with demand, a safe, reliable, high-capacity power grid (section 11, subs. 1 EnWG.) The transmission of electricity must be as economical and environmentally friendly as possible (section 1, subs. 1 EnWG).
3. In addition, the Renewable Energies Act (EEG) stipulates that priority must be given to the feeding-in and transport of electricity from renewable energies. This means, on principle, every kilowatt-hour of electricity produced from renewable energies must be accepted into the grid - if necessary, at the expense of conventionally generated electricity. This promotes the generation of electricity from renewable sources such as wind, sun and biomass. The law accords priority to electricity generated from renewable energy sources over conventionally generated power, and guarantees the operators of EEG generation capacity a fixed revenue per kilowatt-hour. In order to meet their take-off and transmission obligations, the transmission system operators are, under the Renewable Energies Act, obliged to expand the grid as soon is this proves necessary to ensure the take-off and transport of electricity from renewable energies.