Voltwise Power has closed a £153.9 million senior debt financing to support its acquisition of a 460 MW UK BESS portfolio from Smart Metering Systems. Backed by Sandbrook Capital and arranged by Santander CIB, the transaction creates a scaled platform spanning operational, construction and development-stage assets, reinforcing lender confidence in the UK standalone battery storage market.
PROJECT SNAPSHOT
| Field | Value |
|---|---|
| Project | UK BESS Portfolio Acquisition |
| Developer / Owner | Voltwise Power (backed by Sandbrook Capital) |
| Seller | Smart Metering Systems (SMS) |
| Location | United Kingdom |
| Total Portfolio Capacity | 460 MW |
| Operational Assets | 7 projects | 320 MW / 350 MWh |
| Assets Under Construction | 4 projects | 140 MW / 280 MWh |
| Financing Type | Senior debt acquisition financing |
| Debt Amount | £153.9 million (~USD 220 million) |
| Lead Arranger & Underwriter | Santander CIB |
| Syndicate Lenders | NatWest; Kommunalkredit; Siemens Financial Services (Siemens Bank) |
| Transaction Year | 2025 |
UK-based Battery energy storage systems (BESS) developer, Voltwise Power, has completed the successful syndication and close of a GBP 153.9 (USD 220) million senior debt acquisition financing to support its 2025 purchase of a 460 MW UK battery energy storage system (BESS) portfolio from Smart Metering Systems (SMS).
The financing was arranged with the support of Santander CIB and underpins one of the larger recent transactions in the UK standalone battery storage market.
Voltwise is owned by Sandbrook Capital Investment firm, the transaction results in a scaled platform that includes operational, under-construction and development-stage assets, supported by established operational, construction, development and commercial capabilities.
The acquired portfolio comprises seven operational BESS assets with a combined capacity of 320 MW / 350 MWh. These assets are already providing grid services and flexibility to the UK power system. In addition, four projects with a total capacity of 140 MW / 280 MWh were under construction at the time of financing. The portfolio also contains development-stage assets intended to extend Voltwise’s future pipeline and provide optionality for further capacity growth.
Santander CIB acted as M&A Adviser, Sole Underwriter, Bookrunner, Mandated Lead Arranger, Hedge Provider, Original Issuing Bank, and Account Bank for the transaction. Following underwriting, the debt was successfully syndicated to a broader lender group, with NatWest, Kommunalkredit, and Siemens Financial Services through Siemens Bank joining the facility. The expanded lender group increases liquidity depth and diversifies financing sources for the platform.
The transaction reinforced the role of structured acquisition and construction financing in enabling the expansion of large-scale battery storage platforms. It also highlighted ongoing lender participation in the UK BESS sector, supported by a growing base of operating projects and a pipeline of assets moving through construction and development stages.