Rossair specialises in grid-scale BESS projects that support the UK’s transition to a flexible, low-carbon power system. We deliver fully integrated battery energy storage projects, from initial feasibility and system design through procurement, civils and construction to commissioning and long-term performance.
All project delivery is carried out by Rossair, our mechanical and electrical engineering partner, bringing over 50 years of building services and infrastructure experience to every BESS site.
Why BESS Projects Are Critical to the UK Power System
Battery Energy Storage Systems (BESS) are no longer a niche technology; they are now a core part of the UK’s energy strategy. The UK already has the largest installed grid-scale BESS capacity in Europe and is expected to grow several-fold by 2030 as batteries provide flexibility for wind and solar.
Well-designed BESS projects can:
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Provide ultra-fast frequency response and grid balancing, reacting in milliseconds to stabilise the 50 Hz system and prevent blackouts.
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Reduce congestion and support more renewable generation onto constrained parts of the network.
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Create diversified revenue stacks (ancillary services, capacity, balancing mechanism, arbitrage) for investors and asset owners.
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Improve resilience for large energy users by providing backup power and peak-shaving.
With project pipelines and connection queues at record levels, execution quality – from grid studies to construction – is now the main differentiator between “paper projects” and bankable operating BESS assets.
End-to-End Delivery of Grid-Scale BESS Projects
Rossair provide EPC-style delivery across the full lifecycle of BESS projects in the UK.
1. Feasibility, Grid & Land
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High-level and detailed feasibility assessments
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Initial grid capacity checks and DNO/TO engagement
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Site identification, landowner discussions, and access considerations
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Screening for planning, environmental, noise and visual constraints
2. System Design & Engineering
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Technology selection and sizing (MW / MWh, C-rate, connection voltage)
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Single-line diagrams, protection schemes and control philosophy
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Layouts for containerised or building-integrated BESS solutions
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Safety engineering, including fire detection, suppression and segregation
3. Planning & Consents
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Planning application support and environmental documentation
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Noise, traffic, flood risk and ecology assessments (via specialist partners)
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Stakeholder engagement with local authorities and communities
4. Procurement, Civils and Construction – Delivered by Rossair
Rossair provides the on-the-ground delivery of BESS projects:
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Civil works – foundations, compounds, access roads and drainage
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Mechanical and electrical installations, including LV/MV/HV works
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Integration of inverters, transformers, switchgear and auxiliary systems
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Coordination of OEM commissioning engineers and protection testing
Rossair’s long history in complex mechanical and electrical infrastructure means each BESS site is delivered safely, efficiently and in line with grid and regulatory requirements.
5. Commissioning, Grid Compliance & Handover
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Site testing, energisation and performance checks
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Grid code compliance, G99/G100 and relevant performance testing
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Handover packages, O&M manuals and training
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Ongoing operations, monitoring and maintenance support
Types of BESS Projects We Deliver
Front-of-Meter Grid-Scale BESS
Large battery assets connected directly to the distribution or transmission network, providing:
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Dynamic Containment and other frequency services
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Balancing Mechanism and wholesale arbitrage
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Capacity and stability services for the system operator
Co-Located Solar and Wind + BESS
Battery storage co-located with solar farms or wind projects enables:
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Higher grid utilisation and reduced curtailment
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Shaping of output to match off-take agreements
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Shared infrastructure and land use to improve project economics
Behind-the-Meter BESS for Large Energy Users
For energy-intensive sites and campuses, BESS can:
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Reduce TRIAD or peak usage charges
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Provide resilience and backup for critical operations
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Integrate with on-site generation (solar, CHP) and EV charging
Our BESS Project Delivery Process
Step 1 – Opportunity & Grid Review
We begin with your pipeline or site concept and:
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Review grid capacity and potential connection points
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Assess commercial potential and revenue stack options
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Prioritise projects based on viability and timelines
Step 2 – Feasibility & Business Case
We then build the numbers:
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Technical sizing (MW/MWh) aligned to target services
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Capex and opex estimates with sensitivity analysis
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Revenue modelling under different market and policy scenarios
Step 3 – Design, Planning & Consents
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Detailed engineering and grid studies
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Planning application preparation and stakeholder engagement
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Agreement of key design parameters with OEMs and network operators
Step 4 – EPC Delivery with Rossair
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Civil works, electrical balance-of-plant and installation
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OEM equipment integration, testing and safety sign-off
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Programme management to align with connection dates and commercial go-live
Step 5 – Operations, Optimisation & Expansion
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Performance monitoring and availability reporting
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Planned maintenance and fault response
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Options to expand capacity or integrate additional technologies over time
Why Developers and Investors Choose Rossair for BESS Projects
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Specialist BESS focus – Rossair is dedicated to battery storage, solar and infrastructure EPC, aligning with the UK’s rapidly expanding BESS pipeline.
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Proven mechanical & electrical delivery – Rossair has over five decades of experience delivering complex building services and mechanical engineering projects across the UK.
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Grid and policy alignment – We design projects to align with evolving grid connection reforms and the UK’s clean power goals to 2030 and beyond.
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Investor-grade documentation – Bankable designs, clear risk registers, and robust construction and O&M plans to support financing and acquisitions.
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Scalable model – From single 20–50 MW sites to multi-asset portfolios, we deliver repeatable project frameworks for institutional investors and IPPs.
Regional Focus – BESS Projects Across the UK
Rossair deliver BESS projects nationwide, with strong capability across:
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London and the South East – leveraging Rossair’s long-standing presence in London, Hampshire, Surrey and Sussex for on-the-ground delivery and maintenance.
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Wider UK – supporting developers and asset owners with BESS projects near major grid substations, renewable clusters and industrial demand centres.
If you are assembling a BESS pipeline, planning co-located solar + storage, or repowering former fossil sites, we can step in as your delivery partner from early development through to energisation and handover.
FAQs – BESS Projects in the UK
Q1. What size of BESS projects do you deliver?
We typically work on utility-scale and large commercial BESS projects, from around 10 MW upwards, including 2-hour and 4-hour systems depending on the target revenue stack and grid needs.
Q2. How long does a BESS project take from concept to operation?
Timelines vary, but for well-prepared sites with early grid engagement, typical durations range from 18–36 months, driven largely by planning and connection dates rather than construction time.
Q3. What chemistries and configurations do you work with?
Most current UK BESS projects use lithium-ion technology, but we design around your chosen OEM and can support alternative chemistries where appropriate, provided they meet grid, safety and commercial requirements.
Q4. How do you manage safety and fire risk on BESS projects?
We integrate OEM safety requirements with UK standards, combining spacing, compartmentation, fire detection and suppression, and robust monitoring and control systems, backed by Rossair’s long experience in critical M&E environments.
Q5. Can you support developers who already have land and grid agreements?
Yes. We frequently join projects once grid and land are secured, providing detailed design, EPC delivery through Rossair, and commissioning to bring shovel-ready projects into operation.
Discuss Your BESS Project Pipeline with Rossair
If you are developing or investing in BESS projects in the UK, we can act as your technical and delivery partner – with Rossair leading design and project integration, and executing the mechanical, electrical and construction works.
Book a BESS project strategy call
Share your sites, grid positions and timelines, and we’ll outline how we can support you from feasibility to energisation.