UK-based Palmer Energy Technology Limited (PETL), a battery energy storage system startup, has announced the acquisition of Brill Power, a spin-out from the University of Oxford known for its advanced battery management technology.
The deal is backed by a new £5 million Series A round co-led by FirstGroup plc, Barclays Bank, and the University of Oxford.
This transaction marks a significant consolidation of UK-based innovation in the battery energy storage space, bringing together PETL’s automotive-grade BESS technology with Brill Power’s cell-level battery control software. The combination is expected to enhance safety, efficiency, and lifecycle performance in battery deployments across sectors, from electric buses to grid-scale storage.
“PETL’s acquisition of Brill Power enables us to embed the Brill software in all of our systems, instantly giving PETL a leading position in the space to serve customers such as FirstGroup,” said Andy Palmer, CEO and co-founder of PETL.
“With buses at the forefront of the transition to electric vehicles and net zero transportation, I’m delighted to welcome investment from FirstGroup, as well as Barclays and Oxford University, to advance the development of next-generation control systems. This will allow us to accelerate our business and give the UK a leading position in BESS technology.”
Brill Power, founded in 2016 by a team of Oxford engineers and scientists, has developed proprietary technology that improves battery safety and performance by actively managing the current drawn from each individual cell based on its condition. The system helps extend battery life and efficiency—critical for industries like transport and energy storage where downtime or degradation has high cost implications.
Brill Power’s control software is engineered and validated in the UK. With all operational data stored on UK-based servers to support security and compliance.
While Brill Power will now operate under PETL for integrated systems, its brand will continue independently for module sales to third-party partners.
The acquisition and growth capital are part of a broader play to scale PETL’s UK operations, enhance domestic assembly and shorten supply chains. The £5 million funding round was co-led by FirstGroup Energy Limited (the dedicated energy investment arm of FirstGroup plc), which is both a strategic investor and customer of PETL.
“This investment continues our strategy of backing new and innovative companies aimed at supporting our long-term public commitment of achieving a zero-emission fleet by 2035,” said Faizan Muhammad, Investment Director at FirstGroup plc.
“PETL, along with its acquisition of Brill Power, will unlock innovative energy procurement solutions whilst providing second life use cases when batteries are taken off electric buses.”
“It is great to see the coming together of PETL and Brill Power to accelerate their novel energy storage technologies,” said Adam Workman, Head of Investments and New Ventures at Oxford University Innovation.
“Alongside FirstGroup, we hope that the combined business will accelerate the commercialisation of its energy platforms.”
The PETL-Brill Power deal reflects a wider trend in Europe’s cleantech and energy storage ecosystem, where innovation in battery systems, from hardware to software, is seen as essential to achieving net zero targets and ensuring grid stability amid the clean energy transition.
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