Congestion management

Managing capacities at the border

Electrical energy is traded at a national and a pan-European level. The Swiss transmission grid is part of the European interconnected grid, meaning that Switzerland is closely integrated in the European energy exchange. The transmission system operators, including Swissgrid, play a key role in enabling efficient energy exchange as well as secure grid operation. This is because the energy exchange is determined by both commercial and physical factors.

The physical limits of the grid infrastructure, such as lines and transformers, determine how much transfer capacity is available for international electricity exchange at the Swiss borders. The transmission system operators are not always able to provide the capacity demanded by trade. To avoid grid congestion and ensure non-discriminatory access, the capacity at the Swiss borders is awarded through auctions.

NTC – the maximum available limit

The net transfer capacity (NTC) is the maximum transfer capacity that the transmission system operators can provide for cross-border trade. Swissgrid and the transmission system operators in Switzerland’s neighbouring countries are responsible for calculating this capacity for every Swiss border.

An overview of the different auctions

Swissgrid awards the available capacities on the international interconnection lines to traders in stages and for different periods: auctions are held one year, one month and one day (day ahead) before the actual exchange of electricity. Traders can purchase the remaining capacities in intra-day trade.

Year-, month- and day-ahead trading
1/2: Year-, month- and day-ahead trading:
In explicit auctions, traders purchase the cross-border transport capacity separate from the electricity transaction.
Intra-day trading
2/2: Intra-day trading:
«Continuous trading» is a «first-come-first-served» process. In implicit auctions, traders buy or sell the energy, while the available transfer capacity is used automatically.

The awarding of capacities differs depending on the border and the time frame: in the year-, month- and day-ahead auction, Swissgrid holds explicit auctions at all borders. In this case, traders purchase transfer capacity separately from the energy transaction. Traders can then use this capacity within a certain time frame. The energy needs to be bought or sold separately.

In intra-day trading, explicit «continuous trading» is implemented at most Swiss borders. Swissgrid and the neighbouring transmission system operator award the remaining capacity in a «continuous trading» process for which no payment is required. At the border between Switzerland and Italy, Swissgrid and the Italian transmission system operator Terna jointly hold implicit auctions with the EPEX SPOT and GME electricity exchanges: in this case, traders buy or sell the energy in their domestic market; there is no need to purchase capacity separately. The exchanges are then responsible for processing the energy transaction and for any energy exchange across the border.

In congestion management, Swissgrid works together closely with the grid operators in neighbouring countries. Only a joint approach allows the greatest possible amount of capacities to be made available for trading while simultaneously ensuring secure grid operation in Europe and Switzerland. As a result, the NTC values for the international interconnection lines are always jointly defined. Explicit auctions are held by the Joint Allocation Office (JAO S.A.), in which Swissgrid and several other transmission system operators hold participating interests.

Due to the lack of an electricity agreement, Swissgrid is not fully authorised to participate in the coupled electricity markets in Europe and therefore is also not part of the capacity calculation regions. The participating transmission system operators coordinate the calculation of the cross-border capacity across the entire region. Cross-border trade takes place only via implicit auctions. At a European level, Swissgrid is committed to ensuring that Switzerland can cooperate in the European coordination processes, which are vital for the security of the system.

  • Planning grid operation

    The operation of the transmission grid is based on long-term planning. The operators in the grid control room in Aarau use a grid model to prepare an initial forecast of the expected grid situation over a year in advance.

    Learn more



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