Major BESS deals in Germany from Entrix, TMH, Engie

French utility Engie has teamed up with Amsterdam-headquartered energy storage provider Return on a landmark long-term virtual flexibility purchase agreement (vFPA) in Germany, covering 100 MW of battery energy storage systems. The deal – described as the largest fully fixed-price vFPA concluded in Europe to date – is scheduled to take effect in 2027.

Under the agreement, Return will aggregate multiple battery assets through its proprietary technology platform, giving Engie access to flexibility via a single virtual portfolio. Engie will optimise this flexibility across wholesale and ancillary services markets, supporting its efforts to deliver 24/7 green power solutions to downstream customers.

“This vFPA marks a major milestone for the flexibility market in Europe,” said Martin Daronnat, Head of Flexibility and Structured Origination, Germany, at Engie. “It represents a significant step forward in our ability to deliver green power to our customers, complementing our renewable generation portfolio.”

The agreement forms part of Return’s broader European expansion as it scales its cross-border BESS platform across markets including the Netherlands, Belgium, and Spain. Engie and Return said they intend to expand their partnership to additional European countries and to sign further flexibility purchase agreements in the coming years.

Tolling offers

The Mobility House Energy and Bulgaria’s energy and insurance group Electrohold will soon offer a bankable tolling model for battery storage systems in Germany. The Mobility House Energy will handle the optimization and marketing of the systems, while Electrohold Group will provide the financial security for the offering. The new offering is a response to the increasing market risks for battery storage systems and is intended to offer investors an alternative to less secure tolling agreements or purely market-price-dependent operation, the companies said on Wednesday

The tolling contracts would typically have a term of five to seven years after the battery storage systems are commissioned. The minimum pool size should be 50 MW. Both full and partial tolling contracts are available, with the latter usually stipulating a 90/10 or 80/20 capacity split, according to the statement. However, other configurations such as 70/30 or 50/50 are also possible. A payment guarantee covers up to 100% of the annual tolling fee for the entire term. Proof of reinsurance is provided to investors.

In the hedged portion, The Mobility House Energy and Electrohold bear the majority of the short-term market price risk. The Munich-based company assumes full responsibility for deployment decisions, market optimization, and participation in the relevant energy markets for the battery storage systems, but only under strict adherence to the system’s technical specifications and warranty limits.

The Electrohold Group, one of Bulgaria’s largest energy companies, is drawing its financial backing from its balance sheet. In 2024, the company generated revenue of approximately €1.1 billion from its energy business. Its A-rated rating makes the tolling offer bankable and is intended to provide financial security for investors, the company stated.

Mid 2025, Electrohold Trade, the electricity trading and supply arm of the Electrohold Group, and The Mobility House partnered on the optimization of 2.5 GWh of co-located battery storage in Bulgaria.

First grid-supportive battery storage

It is the first battery storage system of its kind to be built in Germany. Last year, Maxsolar was awarded the contract by the distribution network operator Bayernwerk Netz to build a grid-supporting storage system in accordance with Section 11a of the German Energy Industry Act (EnWG). This summer, both parties signed the service agreement for the 5 MW/25 MWh, which is to be built in Wutzldorf, Bavaria. Construction of the battery storage system is scheduled to begin in May, and it is expected to go into operation in October, as Maxsolar announced on Thursday

In this context, a cooperation agreement has been reached with Entrix for the marketing and optimization of the storage system. Entrix’s AI-supported trading and deployment strategies are designed to ensure that the storage system is used in a way that is both beneficial to the grid and economically efficient. The operating mode is primarily geared towards the needs of the local power grid. During periods of high photovoltaic feed-in, particularly during the summer midday peaks, the storage system absorbs excess electricity, thereby significantly relieving the strain on the local grid. During the morning and evening hours, when grid load is particularly high, the storage system is operated in such a way that no additional electricity is drawn from the grid.

Beyond the grid-supporting requirements set by Bayernwerk Netz, the storage system can be used and operated to generate revenue on various trading markets. The project also aims to demonstrate that economic operation and grid support can be combined in a single operating model. “With the Wutzldorf project, we are showing how battery storage systems can reduce grid congestion and increase system stability. This approach offers a cost-effective and scalable way to implement energy storage in regions with limited grid capacity,” says Steffen Schülzchen, CEO of Entrix.