News Synopsis
PROJECT SNAPSHOT
Project: UK utility-scale BESS portfolio
Capacity: 694MW
Location: United Kingdom
Developer: Gresham House Energy Storage Fund plc
Investor: Sumitomo Corporation via Summit Transition Partners
Initial Phase: 397MW across three projects
Future Pipeline: 297MW across two projects
Status: Development / Construction planned
Sumitomo Corporation, through its joint venture Summit Transition Partners Limited (STP), has agreed to invest in a portfolio of five utility-scale BESS projects in the UK. These projects will have a total planned capacity of 694 MW. The projects are being developed by Gresham House Energy Storage Fund plc (GRID). Sumitomo Corporation has entered into a battery storage agreement with Gresham House Limited (GH), the fund manager of GRID.
Sumitomo Corporation formed STP as the majority shareholder, partnering with TPK Holding Co., Ltd. The first phase would consist of an initial capital investment that would involve three projects having a total capacity of 397 MW. The construction would commence during the ongoing fiscal year. Development of the other two projects having a total capacity of 297 MW would proceed simultaneously on the basis of exclusive rights accorded to STP.
GH is among the leading participants in the UK battery storage market, with approximately 1 GW of developed capacity representing around 15% of the country’s operational BESS market. Through the partnership, Sumitomo Corporation plans to combine GH’s project development and operational expertise with its own experience across battery storage development, ownership, optimization, and electricity market participation.
This investment comes at a time when the UK is ramping up its use of renewable sources of energy, with more than half of the nation’s electricity coming from renewable energy sources. Growing use of variable renewable sources of energy has necessitated energy storage facilities that can help balance supply and demand and regulate frequency in the grid. The UK government has also taken steps to facilitate faster adoption of BESS.
The transaction also aligns with Sumitomo Corporation’s investment strategy in the UK energy sector. In July 2025, the company signed a memorandum of understanding with the UK government’s Office for Investment under the Department for Business and Trade to promote business investment opportunities in the country. The current BESS initiative has been positioned as one of the projects developed under that framework.
Beyond the UK market, Sumitomo Corporation is seeking to expand its global battery storage business by leveraging experience gained in Japan. The company has participated in several domestic storage projects, including a battery energy storage installation on Koshikishima Island in Satsumasendai City, Kagoshima Prefecture, and an EV battery station business in Chitose City, Hokkaido. Moreover, with its subsidiary OPTECH Energy Co., Ltd., the company has built up its skills in the optimization and operation of grid-scale batteries in Japan’s power market.
According to Sumitomo Corporation, this project will add value to their renewable energy and power trading operations in the UK, which include wind energy projects. In their statement, the corporation sees large-scale BESS as an integral part of a reliable and cost-efficient power network that can accommodate more renewable energy.
With the combination of Japan’s operational knowledge and its battery storage partnership in the United Kingdom, Sumitomo intends to use both nations as its base for expanding its global business of battery storage. According to the company, this move will help create sustainable and flexible power systems and contribute to the stability of electricity systems as more renewables are being integrated into global power grids.