The financing of grid expansion is a key issue in the context of the energy transition. Building cost subsidies (BKZ; German: "Baukostenzuchuss") in particular play a decisive role in this. These are levied by the grid operator for grid connections of new consumers in order to adapt the grid to the additional power requirements. Further information on the background to BKZ can be found in our blog post from 06.05.2024.
Status quo: dispute over the BKZ obligation
In accordance with their dual function - battery storage systems can both feed in electricity and absorb load - they are also classified as consumers in § 3 No. 15d of the German Energy Industry Act (EnWG). Grid operators therefore also charge the BKZ for energy storage systems. Their feed-in function is not taken into account when calculating the BKZ. Experts criticize this as a potential violation of the freedom from discrimination under Section 17 of the Energy Industry Act. The Düsseldorf Higher Regional Court therefore declared the calculation method used to date to be unlawful. However, the Federal Network Agency is sticking to its legal opinion. A final decision by the Federal Court of Justice (BGH) is still pending.
Changes in 2025
While the decision is still pending, grid operators are adjusting the BKZ in line with the expected grid expansion requirements. Avacon and E.DIS, for example, have seen massive increases in BKZ at all voltage levels. The BKZ in the medium-voltage grid rose by over 96% from €55.70 to €109.37/kW at Avacon and by as much as 137% from €50 to €118.66/kW at E.DIS. In contrast, the BKZ at Pfalzwerke and EWE Netz fell by 20% and 28% respectively (medium voltage). All changes in the BKZ at the distribution grid level are summarized in Figure 1.
Modification of the calculation basis
The Federal Network Agency commented on the BKZ levy in a position paper dated 20.11.2024. In it, the BKZ calculation basis is reformed, but the BKZ obligation for battery storage systems remains in place, contrary to many expectations.
The aim of the new regulations is to increase planning security for grid operators and project developers and to ensure that costs are incurred where they are actually generated by grid investments. The new calculation basis is to be based on a five-year average of power prices in order to cushion the price fluctuations outlined above and increase planning certainty for battery storage projects.
The following chart shows the current regional distribution of the BKZ in Germany at the distribution grid level.
Regionalization and transparency at transmission level
Within a distribution grid, the BKZ is uniform in accordance with Section 17 EnWG, which means that all grid connections of the same quality receive the same BKZ. However, transmission system operators (TSOs) have the option of adjusting the BKZ in five differentiated stages from 100% to 20%. This adjustment takes into account a so-called regionalization factor (see Figure 3), which takes into account regional differences in grid expansion costs. The BKZ for the four TSOs is thus calculated using the formula:
This differentiation allows grid connection points that contribute to relieving the overall system to benefit from a reduced BKZ. Based on the BKZ published by the transmission system operators of €99.29/kW at the extra-high voltage level and €114.19/kW at substations between extra-high and high voltage, this results in BKZ of:
Conclusion
The BNetzA's position paper certainly provides for exciting changes with the new calculation basis using the five-year average and the regional staggering of the capacity price at transmission grid level. For battery storage systems, however, the hoped-for abolition of the BKZ has not materialized, although final clarification by the Federal Court of Justice is still awaited.
In the dvlp web GIS, our users can therefore continue to find the currently valid BKZ and regionalization factors of all grid operators at all voltage levels.
