Cross-Class Value of Battery Energy Storage in Low-Voltage Grids: Grid Relief, Dispatch-Coupled Ageing, and Cost-Effectiveness

Abstract

The German low-voltage (LV) distribution grid faces stress from the build-out of distributed photovoltaic (PV) units. Battery storage is widely proposed as a solution, yet the literature is partitioned by storage scale, placement, and how ageing is treated. This study introduces a unified cross-class assessment of the three structurally distinct LV storage classes under one methodology: residential PV home storage (Class I, 5 kWh), feeder-level DSO string storage (Class II, 10–50 kWh, one unit per feeder end), and market-coupled district storage (Class III, 50–500 kWh, EPEX-scheduled). All classes share the same 1 min load and PV time series, the same voltage-guided PnetU dispatch with class-specific extensions, and the same Naumann–Wang LFP ageing model with rainflow counting, evaluated to a 20-year state-of-health horizon across representative and limiting multi-feeder German LV networks, with degradation treated as a dispatch outcome. Correctly modelled networks prove largely voltage-robust; on the limiting Kerber feeders studied, storage does not restore grid-code compliance at any tested size. Grid-supportive operation yields little grid benefit and is ageing-neutral only where it is not needed, becoming costly without adequate benefit on the stressed feeders studied. The value of LV storage therefore rests on dispatch-resolved lifetime, self-consumption and curtailment reduction, and market participation rather than grid service.