New rules in the BDEW Musterwortlaut for medium‑voltage grid connection

The BDEW has developed a model wording for the Medium-Voltage Technical Connection Rule, the VDE-AR-N 4110 (TAR-Mittelspannung). This rule forms the basis for the technical connection conditions of the currently 866 distribution system operators in Germany. These operators are allowed to supplement the currently applicable TAR with their own additions, for example by introducing additional requirements. In practice, this has led to different solutions across the country.

The BDEW has now proposed a harmonization through its model wording: network operators who adopt this model wording in the future will no longer need to maintain or expand their own technical connection conditions (TAB) independently, nor will they have to justify them to connection applicants (requirement under §19 paragraph 1a of the German Energy Industry Act – Energiewirtschaftsgesetz, EnWG).

Our expectation:In the future, smaller network operators in particular are likely to adopt the model wording rather than developing their own additional regulations and justifying their necessity. In doing so, they can benefit directly from the harmonization and simplify the connection process for themselves and for connection applicants.

Independently of this development, the VDE FNN (the standardization committee) is currently working on a revision of VDE-AR-N 4110, which is expected to be published later this year. The model wording still refers to the currently valid version of the rule from September 2023. It can therefore be assumed that some of the harmonization elements contained in the model wording may already be incorporated into the upcoming revision.

So it is worth taking a closer look.

What impact could the proposed changes in the model wording have on ongoing projects?

To what extent should project developers and all stakeholders involved in the construction or planning process now pay particular attention and potentially incorporate adjustments or new considerations into their projects?

• Response deadlines for grid connection inquiries: It appears likely that formal responses could become more standardized. For project developers, this will probably mean greater transparency in the process, without necessarily resulting in a noticeable reduction in the actual processing time.

• Ramp-rate requirements for energy storage: stronger harmonization of permitted operating parameters could lead to more conservative system designs in the future. In the planning phase, technical reserves or alternative operational strategies may therefore become more relevant.

  Expected maximum ramp rate for energy storage systems:22% per minute (permissible requirements by distribution system operators: 6–22%), previously up to 39.6% per minute (permissible requirements by distribution system operators: 4–39.6%).

• Protection concepts for installations with multiple transformers: The trend toward more differentiated protection requirements per transformer station may intensify. For existing concepts, this could mean that protection engineering needs to be analyzed in greater detail earlier in the project and, if necessary, reassessed.

• Metering technology and event recording for larger installations: An expansion of requirements for recording grid events is conceivable. Project stakeholders should therefore monitor whether additional components or interfaces may need to be integrated into plant architecture in the future.

• Grid-independent auxiliary power supply: A stronger focus on the availability of communication, protection and secondary systems suggests that the internal power supply of the grid connection station may need to be designed more robustly overall. This could have implications for space requirements, system architecture and interfaces.

Summary

In summary, the upcoming changes to the BDEW model wording and the revision of VDE-AR-N 4110 present both opportunities and challenges for network operators and project developers. Particularly for projects that are not yet operational, the new requirements may also introduce economic risks and uncertainties.

While the harmonization and simplification of the rules will make implementation easier for smaller network operators and create greater uniformity in the connection process, project developers and all parties involved in construction and planning must closely monitor which of the proposed requirements will actually be implemented.

It is therefore advisable to follow developments closely in the coming months, analyze potential economic impacts at an early stage, and maintain sufficient flexibility in project design to remain operational under changing regulatory conditions while ensuring compliance with the applicable requirements.

Note: This article reflects our practical experience and is not a substitute for legal advice. Feel free to contact us if you're planning a project - we’ll support you with hands-on expertise.