Power firm RWE has partnered with distributed battery storage firm Polarium for a battery-based virtual power plant (VPP) in Germany.
Starting later this year, RWE will optimise the dispatch of at least 50MW/135MWh of battery storage capacity from the distributed portfolio of Polarium, a Sweden-headquartered systems manufacturer and solutions provider.
It will initially use 1,600 distributed batteries aggregated via Polarium’s cloud platform, but the firm has long-term plans to increase that to 10,000, a capacity of 300MW/810MWh. It implies an average battery size of c.30kw/80kWh, meaning these are likely to be commercial & industrial-sited rather than residential batteries.
RWE said the aggregation will enable real-time control and secure market participation while unlocking value from underutilised assets and grid infrastructure.
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Ulf Kerstin, CCO at RWE Supply & Trading, said: “By working with Polarium, we are bringing thousands of smaller storage units into the flexibility market, where they can contribute to make the energy system more robust, generate additional value and help to keep the system in balance in real time.”
Leif Ottoson, CEO of Polarium: “This agreement shows how distributed battery systems, originally deployed for mission critical infrastructure, can also play a meaningful role in the energy system.”
The batteries are primarily deployed by Polarium for backup power at customer sites, with remaining capacity pooled virtually via its platform. That capacity is being made available to RWE under a tolling agreement. Polarium is granting access to aggregated flexibility for commercialisation across flexibility markets, while RWE connects to the platform to access and optimise the combined capacity.
RWE said it builds on another multi-asset tolling deal it entered into with virtual aggregation and tolling platform Terralayr.
Germany is one of the most mature markets in the world for distributed batteries, both residential and C&I, and that is enabling the scaling of battery-based VPPs such as this one.
In early 2025, distributed battery pioneer sonnen had its home battery units qualified by transmission system operator (TSO) TransnetBW, further enabling VPP participation. The firm has previously claimed its combined Germany battery VPP could reach over 1GWh, possibly already.
Chris Bernkopf, CEO of flexibility and trading platform Podero, recently wrote about the huge untapped potential of home batteries on the grid in Europe in a guest blog for us.
