Planning to install electricity storage? Then you should be aware of this subsidy. The construction cost subsidy can make storage projects expensive – but a court ruling is now fundamentally questioning the previous model.

What is the construction cost subsidy (BKZ)?

The BKZ is a one-time payment that is due when a project is connected to the power grid. The aim is to allocate grid expansion costs proportionally to project developers – in particular to avoid oversized connection capacities. Until now, the so-called power price model has been common practice: the subsidy is calculated based on the ordered connection capacity – regardless of how often and how much electricity is actually consumed.

What problems does this pose for battery storage systems?

Battery storage systems are not like traditional consumers. They only draw electricity for a short period of time, store it temporarily, and feed it back into the grid at a later point in time. This grid-friendly flexibility is not taken into account in the flat-rate power price model. Storage systems thus pay the same subsidy as industrial plants with permanent electricity consumption – even though their grid requirements are lower.

The legal background to the Higher Regional Court decision in Düsseldorf

In December 2023, the Higher Regional Court of Düsseldorf caused a stir with a ruling: it declared the flat-rate collection of construction cost subsidies (BKZ) for battery storage systems under the performance-based pricing model to be illegal – at least in its current form. But what is the court's reasoning? Two key provisions of the Energy Industry Act (EnWG) provide the legal basis: Sections 17 and 31.

Section 17 EnWG and Section 31 EnWG explain: Connection – yes but fair

According to Section 17 (1) EnWG, grid operators are obliged, among other things, to connect battery storage systems to their grid under reasonable, non-discriminatory, and transparent conditions.

In the case of the Higher Regional Court of Düsseldorf: The court clarified that battery storage systems are not typical consumers. Applying the usual performance-based pricing model to storage systems would therefore constitute impermissible equal treatment of unequal circumstances – i.e., discrimination within the meaning of Section 17 EnWG.

Section 31 EnWG enables operators of storage facilities to defend themselves against unreasonable behavior by grid operators. They can involve the Federal Network Agency (BNetzA) via a so-called abuse procedure. The BNetzA then checks whether a grid operator is violating applicable law or approved regulations.

This is exactly what the operator did in the present case. The BNetzA initially rejected the application, but the Higher Regional Court overturned this decision and obliged the authority to re-examine the case. A decision by the Federal Court of Justice is expected on July 15, 2025.

What does this mean for project developers?

The situation remains uncertain until the Federal Court of Justice reaches a decision. Legal clarity regarding the grid connection of battery storage systems is crucial so that project developers can plan reliably and implement projects more quickly.

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