Grid expansion

The German electricity grid will require comprehensive alignment in order to achieve the ambitious targets of the energy transition. In addition to a continuous increase in quantitative 

transmission capacity, this also addresses the issue of qualitative grid expansion to enable a more efficient and intelligent operation of the existing infrastructure.

Expanding and converting the electricity grid

Grid expansion

Redesigning the electricity grid means more than just building new lines. It is also important to make better use of the existing capacities. dena is presenting insight from two ground-breaking studies.

Grid expansion as the foundation for a successful energy transition

Increasing numbers of decentralised suppliers of renewable energies and rapid fluctuation in power generation – these two aspects concisely summarise the ongoing transformation that the electricity grid must successfully overcome. dena keeps its eye on “work in progress” within the German electricity infrastructure, brings together important stakeholders in the energy sector and prepares concepts for innovative solutions: for instance with its large-scale analyses and the recommendations in the dena Grid Study II and the dena Distribution Grid Study. The results suggest the wisdom of a two-pronged approach: first it will be necessary to build new power lines; secondly, it is imperative to exploit a range of methods that will improve the capacity utilisation of the existing electricity grids.

dena Grid Study II: Grid expansion in the area of extra-high voltage

Applying a broad approach to system optimisation, the dena Grid Study II provides a robust foundation to develop extra-high-voltage grids in Germany. The study investigated the grid infrastructure requirements if renewable energy sources are expanded to account for 39 percent of electricity supply by 2025. Here, the study considers a variety of different transmission technologies, an increase in storage capacities, demand-side measures to relocate load and an increase in European collaboration in electricity trading. The results elucidate that expanding and modernising the grid infrastructure will play a crucial role, as the discrepancy between increasing the share of renewable energy sources and the capabilities of the electricity grids would simply become too severe. 

dena Distribution Grid Study: The energy transition at regional level

While the dena Grid Study II provides recommendations for extra-high-voltage grids, the dena Distribution Grid Study scrutinises the regional grid level. It successfully outlines the future challenges, providing clear calls for recommended courses of action that system operators accommodating a high proportion of renewable energy sources are already putting into practice in their regions. The necessary expansion and conversion of the German electricity distribution grids were investigated in detail based on two alternative expansion scenarios.

The core insight confirms that there is a significant need for action. Distribution grids face the new challenge of how to efficiently integrate fluctuating levels of renewable energy sources, as most of the renewable generation capacity is currently, and will remain in future, connected to the electricity distribution grid. It will therefore be impossible to make full use of the renewable generation capacity that is planned for installation by 2030 without expanding and converting these grids.

Besides necessary expansions of the energy infrastructure, the study also analysed technical options to reduce grid expansion requirements. In particular, the use of innovative grid operational resources, the adaptation of technical guidelines and down-regulation of generation peaks of decentralised power generation units could reduce the need for grid expansion. However, further research into the efficiency and technical design of these measures is required.

Our projects

dena Distribution Grid Study

The dena Distribution Grid Study is a detailed examination of the need for expansion and conversion in the German electricity distribution grids based on two alternative expansion scenarios for renewable energy sources. The results highlight a significant need for expansion of the high, medium and low voltage as well as the intermediate transformer levels by 2030.


  • Publication: December 2012
  • Partners of the study: 17 companies (with a focus on grid operation and energy supply)
  • Involvement of a board of expert advisers from ministries and associations
  • Agents: dena, Technical University of Dortmund / ef. Ruhr GmbH, Prof. Dr. Gert Brunekreeft

Grid Study I and II

With the help of Grid Studies I and II, dena presents the measures which will allow the German electricity grid to meet the challenges of the future: through targeted grid expansion and at the same time optimising the existing energy infrastructure.


  • Grid Study I: released in February 2005
  • Grid Study I: 17 partners from the industry (grid and installation operators as well as their associations) as well as the Federal Ministry for Economic Affairs and Energy (BMWi) and the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB)
  • Grid Study II: released in November 2010
  • Grid Study II: 14 partners from the industry (grid and installation operators as well as their associations) as well as the Federal Ministry for Economic Affairs and Energy (BMWi) and the Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB)