Grid expansion planning: A reflection of the heterogeneous landscape of distribution grid operators

Analysis of regional scenarios and grid expansion plans according to Sec. 14d EnWG with a focus on electromobility

On April 30, 2024, grid expansion plans (GEPs) for the distribution grid were published for the first time on the VNBdigital website in accordance with the legal basis of Section 14d of the Energy Industry Act (Energiewirtschaftsrecht – EnWG) [1]. Of the more than 800 DSOs in Germany, 81 DSOs are obliged to publish GEPs. They must meet at least one of the following criteria: serve at least 100,000 customers via their grid or/and in the previous two years, more than 3 % of energy generation from onshore wind energy or photovoltaics was curtailed by the DSO. The GEPs are based on the previously published regional scenarios of the six planning regions, in which the expected ramp-up of renewable energy plants and loads (e. g. heat pumps, charging points for electric vehicles, etc.) is shown for the individual regions. The new regulation on GEPs is intended to create more transparency and clarity in grid expansion at the distribution grid level.

As part of unIT-e², the regional scenarios and grid expansion plans were examined with regard to the consideration of electromobility. This discussion paper highlights differences and inconsistencies in the methodology and assumptions of the reports based on the example of electromobility. Our aim is to promote a more standardized methodology for the preparation of regional scenarios and GEPs in order to enable more reliable and efficient grid planning. In addition, the documents in their current form are hardly usable for science and industry due to their format and varying quality.

In their GEPs, the DSOs that are obliged to publish consider both their own distribution grid and the grids of downstream DSOs that are not obliged to publish, meaning that the GEPs cover the entire German distribution grid. The total investment requirement is calculated at around € 227 billion (see Figure 1), although some DSOs have only published incomplete cost data. According to a rough estimate based on the grid circuit lengths of the DSOs with missing information, the total investment requirement could be around € 240 billion.

Our Findings

1. Use of different methodologies
   The planning regions are based on various scenarios from the grid development plan of the transmission system operators or use their own methods.

2. Using different units, regionalization and missing data
   • Various units are used to determine the ramp-up of electromobility and assumptions made for conversion are missing.
   • Regional resolution: data is shown at planning region, grid area or federal state level.
   • Heavy-duty vehicle electrification only partially taken into account.
3. Assumptions used in the grid expansion plans
   In divergence from the regional scenarios, some distribution system operators use their own assumptions for the ramp-up of electromobility in their grid expansion plans.

4. Identification of flexibility requirements and services
   The topic of flexibility plays little or no role in the regional scenarios and grid expansion plans (although required under Section 14d EnWG).

Our Suggestions

1. Use of standardised methodology for comparability
   The methodology used should be consistent across the planning regions.

2. Comprehensive transparency
   • Use of standardised units across planning regions or specification of the assumptions made for their conversion
   • Use of a consistent regional resolution: all data should be provided at planning region level
   • Heavy-duty traffic should be taken into account in all planning regions.
3. Regional scenarios as a basis for grid expansion planning
   All grid operators in a planning region should use their common scenario as the basis for grid expansion planning in order to ensure comparability and consistency.

4. Identification of flexibility requirements and services
   The regulatory authority should specify the form in which the demand, potential and utilisation of flexibility must be indicated in the regional scenarios and how this is to be taken into account in the grid expansion plans.

Further information

• Series of articles on the characterisation of low-voltage grids and grid representatives: Distribution grids in the Climate-Neutral Energy System – Scenarios for Consumption, Generation and Grid Operation – FfE

Literature

[1] VNBdigital – das Netzportal Ihrer Verteilnetzbe-treiber. In https://www.vnbdigital.de/. (Abruf am 2025-01-13); Berlin: BDEW Bundesverband der Energie- und Wasserwirtschaft e.V., 2025.