The CNMC standardises the information on access capacities that Distribution System Operators must publish
Published on 21st May 2025
On 19 May 2025, the Resolution of the National Markets and Competition Commission (CNMC), dated 30 April 2025, was published in the Official State Gazette, establishing the formats for the publication of access capacities for electricity demand and generation facilities.
Distribution System Operators (DSOs), like the Transmission System Operator (TSO), are obliged by energy sector regulations to publish the access capacity of the grid nodes they operate. Until now, the information to be published by the aforementioned DSOs was that indicated in article 12 of Circular 1/2021 for generation access capacity and in article 16 of Circular 1/2024 for demand access capacity. Although these articles establish the minimum information to be published - the "what" - they do not determine the "how" this information is to be published.
In practice, this has meant that DSOs have been publishing information on the capacity of their nodes in different formats, which makes it difficult to aggregate and analyse the data published, with the negative implications this entails for the sector's agents in terms of efficiency and resource allocation. The unification of the formats in which this information is published has been one of the recurring demands of the sector's agents.
Content of the Resolution
The resolution sets out the following key points that we would like to highlight:
- Editable formats: the obligation is established for files to be published in editable formats (XLS and CSV), whereas some DSOs have been publishing only in non-editable format (PDF).
- Standardised nomenclature: the nomenclature to be used in the published files and the specific order to be followed in relation to the data categories is standardised.
- Information regarding positions: the number of positions with occupied capacity and free capacity in each of the nodes shall be indicated. In the case of publication of access capacities for demand facilities, only for substations with a voltage above 66 kV.
- Majority affected node: the major affected node of the transmission grid must be indicated.
- Nodes 0*: nodes without capacity, but which could obtain capacity with reinforcements in the distribution grid, shall be indicated. In these cases, a methodological note shall be published indicating, in general terms, the types of reinforcements that have been taken into account.
Impact on the sector
The entry into force of the provisions of the aforementioned CNMC Resolution will not take place before the time established in the detailed specifications for demand access capacity to the electricity networks to be approved by the CNMC, with the exception of the publication relating to the columns on information on positions in substations, which will come into effect within one year from the time when the obligation to publish information on demand by the operators becomes effective. In any case, there is nothing to prevent DSOs from beginning to adapt their capacity publications to the content of this Resolution, and it would be desirable for them to do so.
The approval of the aforementioned Resolution should be viewed positively as, although somewhat belatedly, it fulfils a historical demand made by the sector's agents and it is to be hoped that it will facilitate their work when analysing the state of the distribution grid.
Should you wish to know more about the regulation of the electricity sector, please do not hesitate to contact one of our experts listed below or your usual contact at Osborne Clarke.
