Grid fees for BESS

Commissioned by ECO STOR

Lion Hirth, Clemens Lohr, Anselm Eicke

2025

Concerns about grid congestion are the main reason grid operators hesitate to connect utility-scale batteries, typically requiring operational restrictions in exchange for connection. With battery developer ECO STOR, we developed a quantifiable definition of grid-supportive behavior and applied it to two battery sites in the distribution grids of Schleswig-Holstein and Bavaria. Simulations show that batteries already reduce redispatch costs slightly today, though only by chance. A dynamic energy-based grid fee reflecting expected congestion would cut redispatch costs substantially without undermining the batteries’ business case. This report was originally published in German.

Large-scale batteries will play a key role in the electricity system over the coming decades, particularly in balancing generation and consumption in the short term. The growing interest in battery investments is therefore very welcome. While their value for system balancing is undisputed, their impact on the grid remains a matter of debate. At the heart of this discussion lies a central question: how grid-friendly are large-scale batteries? The short study Grid utility of large-scale batteries (published on 4 September 2025, also available in German) answers it for two concrete battery projects and also explores different approaches and policy instruments that could enhance the grid-friendliness of large-scale batteries.

On behalf of ECO STOR, we also published another study as part of the AgNes consultation that specifically addresses battery-specific grid fees. The aim of this paper was to structure the discussion on grid-friendliness and grid fees for large-scale batteries, to evaluate various design options qualitatively and quantitatively in terms of their incentive effect on grid-friendly behavior, and finally to develop a concrete proposal for a special battery grid fee. The complete consultation paper can be found here.