IN Brief:
- Eelpower Energy has acquired the 50MW/100MWh Stoneworthy BESS project in Devon from RES.
- The project is located south of Pyworthy substation, with construction planned for 2027.
- UK storage development is increasingly shaped by grid proximity, financing, planning status, and delivery certainty.
Eelpower Energy has acquired the 50MW/100MWh Stoneworthy battery energy storage project in Devon from RES, adding another consented UK asset to its grid-scale storage pipeline.
The project is located south of Pyworthy substation and is scheduled to begin construction in 2027, with commercial operation expected in 2028. Financial terms have not been disclosed. Once operational, Stoneworthy will add 100MWh of storage capacity to Eelpower’s portfolio as the company targets more than 1GW of grid-scale battery assets.
The acquisition reinforces the continuing value of consented and grid-positioned storage projects in the UK market. Early-stage pipeline volume remains high, but the market is increasingly focused on assets with planning progress, clear connection routes, credible construction timelines, and a route into operation. Stoneworthy’s proximity to existing electrical infrastructure is therefore a central part of its development case.
Battery storage projects are being built into a power system facing several overlapping pressures. Renewable generation is increasing, transmission and distribution constraints remain significant, connection queues are under reform, and system operators need more flexible resources to manage short-term balance. Batteries can provide response speed, peak shifting, balancing-market participation, and local flexibility, but those functions depend on connection capacity and technical integration.
Devon is becoming an active area for storage development. The 125MW Broadclyst battery project in East Devon has already secured consent close to major grid infrastructure, reinforcing the regional pattern around substations and network access. South West England has strong renewable resources, growing demand, and grid constraints that make flexibility increasingly valuable.
Storage finance is also becoming more selective. The £141m financing package for three UK BESS projects backed by Gresham House showed how lenders are now supporting assets with clearer delivery routes, defined durations, and grid-connection pathways. Eelpower’s acquisition sits within the same maturing market, where a project’s value depends on much more than its headline megawatt rating.
The two-hour configuration at Stoneworthy reflects a common UK storage design. A 50MW/100MWh system can provide two hours of full-power discharge, making it suitable for a range of trading, balancing, and flexibility services. Longer-duration storage is attracting more policy and investor attention, but two-hour batteries continue to dominate much of the near-term pipeline because they balance capital cost, market access, and operational flexibility.
The delivery challenge remains substantial. A grid-scale BESS requires battery containers or enclosures, inverters, medium-voltage transformers, switchgear, protection systems, control software, fire-safety systems, civil works, security, communications, grid interface equipment, and commissioning resource. Each element has to align with planning conditions, grid-code requirements, warranties, safety standards, and market participation rules.
Connection timing will be one of the main tests. UK storage projects are often announced years before energisation because network studies, reinforcement works, equipment procurement, and construction sequencing all affect the schedule. A planned 2027 construction start and 2028 commercial operation date put Stoneworthy into the period when the UK’s storage build-out is expected to become more disciplined, with greater separation between speculative pipeline and deliverable assets.
Sites close to substations remain attractive because shorter connection routes can reduce electrical losses, land complexity, cost, and programme risk. They do not eliminate planning sensitivity or grid constraints, but they can improve the project’s chance of reaching operation in a market where flexibility is needed faster than many reinforcement schemes can be delivered.
Stoneworthy’s next phase will be defined by practical delivery: procurement, detailed design, grid works, construction, commissioning, and optimisation. The commercial case will be tested once the asset begins operating across wholesale, balancing, ancillary, and capacity-market opportunities, but the project has first to move from acquisition into energised infrastructure.
