On July 15, 2025, the Federal Court of Justice in Germany (BGH) confirmed in a landmark decision that grid operators may charge a construction cost subsidy (BKZ) for connecting battery storage systems—even if the storage system is exclusively grid-connected and does not consume any electricity on site. The ruling has a direct impact on the planning and cost structure of storage projects in Germany.

What is a construction cost subsidy?

A construction cost subsidy is a one-time contribution that grid operators can charge if a connection incurs additional costs – e.g., due to necessary grid reinforcements. The amount is usually based on the power price model, i.e., on the maximum connection power, not on actual usage or feed-in.

The specific case

In 2021, a storage operator applied for the connection of a grid-connected battery storage system. The grid operator demanded a construction cost subsidy in accordance with the Federal Network Agency's 2009 position paper. The Federal Network Agency did not see this as discrimination – unlike the appeals court, which demanded a re-examination. The Federal Court of Justice has now overturned this decision and strengthened the position of grid operators.

What does the Federal Court of Justice say?

The Federal Court of Justice clarifies:

• Battery storage systems may be treated like other end consumers when connected to the grid, as they draw electricity from the grid.

• The power at the grid connection point remains decisive – even if energy is fed back into the grid later.

• The potential grid-supporting effect of storage systems (e.g., in the event of bottlenecks) does not justify automatic exemption from the surcharge.

• It is at the discretion of the grid operator whether and how grid-supporting behavior is taken into account when levying the surcharge – provided this is done without discrimination.

Relevance for storage projects

The ruling creates legal certainty for grid operators and project developers alike. One thing is clear: anyone who wants to connect a battery storage system to the power grid must take potential construction cost subsidies into account in their profitability calculations and site selection. EU legal objectives such as facilitating access to the grid for storage systems do not stand in the way of this, as there is national leeway and storage systems are already subsidized in other ways.‍

Planning security through a clear legal situation

The ruling by the Federal Court of Justice now confirms that construction cost subsidies remain a key control instrument for grid connections, including in the context of energy storage.

At Scale Energy, we support companies, municipalities, and energy managers in the strategic implementation of storage solutions. Our storage solutions are scalable, intelligent, and future-proof—just like the requirements for the grid.

Are you planning a storage project? Contact us for an in-depth assessment of your connection options and a free site analysis.