Alpiq acquires 238MWh Bollingstedt battery

Alpiq is acquiring the operational Bollingstedt battery energy storage system in Schleswig-Holstein from ECO STOR, adding 103.5MW of power and 238MWh of storage to its European flexibility portfolio. The plant has operated since June 2025 and will become Alpiq’s first operating large-scale battery in Germany.

The transaction terms have not been disclosed. Bollingstedt’s power and energy ratings give the plant a nominal duration of around 2.3 hours at full output, positioning it for short-duration wholesale optimisation and system services rather than prolonged energy supply.

ECO STOR developed and built the facility, and the acquisition extends an existing relationship between the companies. They signed a long-term tolling agreement in November 2025 for the Schuby battery project in northern Germany, which ECO STOR also built and operates.

Bollingstedt becomes Alpiq’s third operational BESS and its largest to date. The other operating assets are the 100MW Cheviré battery in the Nantes Saint-Nazaire area of France and a 30MW system at Valkeakoski in Finland, while more than 250MW of further battery projects are under construction or close to commissioning.

Alpiq has also widened its development position through its acquisition of a 90% stake in Harmony Energy in July. That transaction brought a multi-gigawatt pipeline spanning the UK, France, Germany, and Poland, but Bollingstedt differs from pipeline capacity because the plant is already operating and can contribute revenue immediately.

Germany is simultaneously changing the framework around battery connections and network charging. Qualifying storage projects retain grid-fee exemptions under current transitional arrangements, while the longer-term treatment of storage remains part of wider reform. The distinction has a direct bearing on project economics because a battery imports electricity when charging and exports it again when discharging.

A poorly designed tariff can therefore expose storage to network charges that treat charging like ordinary final consumption even where the asset is subsequently providing flexibility back to the system. Conversely, a blanket exemption does not remove the network costs created if batteries charge at times and locations where the grid is already constrained. Future tariff design has to distinguish between useful flexibility and behaviour that merely follows wholesale prices without regard to local network conditions.

Bollingstedt’s location in Schleswig-Holstein places it within a region characterised by substantial renewable generation and large north-to-south electricity flows. A 238MWh battery cannot substitute for long-distance transmission reinforcement, but it can alter the timing of local power flows, respond to short-duration system imbalances, and provide reserve services without the start-up delays associated with thermal generation.

Its commercial performance will depend on how those opportunities are combined. Batteries can participate across wholesale spreads, balancing markets, reserve services, and contracted arrangements, but each dispatch consumes part of the asset’s finite cycling capability. Revenue optimisation therefore has to account for cell degradation, round-trip losses, warranty conditions, state-of-charge limits, and periods when capacity must be held in reserve.

Operational availability becomes increasingly important as competition grows. A battery that is unavailable during a high-value price interval or system event cannot recover that lost opportunity later in the same way that a generator with fuel in store might. Inverters, transformers, cooling systems, battery-management equipment, communications, and control software all contribute to whether the nominal 103.5MW rating is actually available when requested.

Alpiq is consequently building a portfolio that combines ownership, development, and contracted access rather than relying on one route into the storage market. Bollingstedt provides an immediate operating position in Germany, while Harmony Energy and Alpiq’s own projects provide future capacity. The useful benchmark will be how the operating fleet performs as German storage moves from an asset-development market towards one increasingly defined by dispatch quality, tariff exposure, and competing flexibility capacity.