BW ESS, Zelos partner on 1.5 GW of large-scale battery projects in Germany

Zurich-based BESS owner-operator BW ESS has another new partnership in Germany, joining Berlin-based energy storage developer Zelos Energy Developments to enact plans to co-develop up to 1.5 GW of projects in the north and east of Germany.

The targets will be within the region operated by 50 Hertz, a transmission system operator (TSO) that operates 220 kV and 380 kV networks in the north and east of the country. BW ESS said it will be targeting Mecklenburg-Vorpommern and Sachsen-Anhalt for the new fleet additions, aiming to achieve ready-to-build status in 2025-2027.

In February, BW ESS and developer MIRAI Power announced plans for 1 GW of BESS additions in southern Germany. Like that deal, BW ESS will focus on engineering design and construction, global procurement, securing revenue, and project financing, and Zelos Energy Developments will focus on securing land, grid, and permits.

It’s the latest in the ongoing BESS expansion in Germany, as the largest electricity market in Europe continues to add grid-scale BESS as part of a catch-up effort to a small-scale battery push. Small-scale systems in the country have proliferated as part of a need to offset very high electricity prices and provide security, with recent data from the German Solar Industry Association (BSW-Solar) suggesting around 19 GWh were installed at the end of 2024, with 15.4 GWh from residential BESS.

BSW-Solar further projected that large-scale battery storage capacity could increase fivefold over the next two years at 7 GWh, a figure that may be exceeded by the ongoing build-out.

That said, the grid-scale BESS boom is happening: transmission and distribution network operators told pv magazine there were around 340 GW of grid-connection requests from large-scale storage systems at the start of 2025.

BW ESS noted it has more than 500 MWh of operating BESS projects, with over 1 GWh under construction and a development pipeline of near 7 GW.