Battery Energy Storage Systems (BESS) are now a core part of UK energy infrastructure. As grid-scale and commercial battery projects accelerate, principal contractors, civils firms, and EPC delivery teams are increasingly required to identify specialist partners who can reliably deliver BESS facilities on time and to programme.

This guide lists UK-active contractors and delivery partners involved in the construction of battery energy storage facilities, with a specific focus on construction, civils, balance-of-plant, and grid-connection delivery.

It is written for people building BESS sites, not selling batteries.

Who this list is for

• Principal contractors delivering BESS or energy infrastructure projects
• Civils and groundworks contractors tendering BESS compounds
• EPC teams assembling delivery partners
• Grid, HV, and substation interface contractors
• Project managers responsible for BESS site delivery and sequencing

If you are trying to understand who actually builds BESS sites, rather than who owns or finances them, this list is intended to help.

Top UK BESS Contractors (construction & delivery focus)

1. Ameresco

Ameresco operates as an EPC contractor on large-scale energy infrastructure projects, including utility-scale BESS facilities in the UK. The company is involved in full project delivery, from construction through to commissioning, and is typically engaged on complex, grid-connected battery sites.

Website: ameresco.com

• EPC delivery of grid-scale battery facilities
• Coordination of civils, BoP, and electrical scopes
• Programme delivery on transmission-connected sites

2. Clarke Energy

Clarke Energy is active in the delivery of battery energy storage projects as a principal contractor, with public references across UK BESS developments. The business is commonly engaged where projects require strong coordination between battery systems, civils, and grid interfaces.

Website: clarke-energy.com

• Principal contractor or EPC delivery
• Construction coordination and site management
• Interface management between battery suppliers and grid works

3. Equans (UK & Ireland)

Equans delivers energy infrastructure projects across the UK and Ireland and has positioned itself as a delivery partner for solar-plus-storage and standalone BESS schemes. The organisation operates at a scale suitable for multi-MW commercial and grid-connected projects.

Website: equans.co.uk

• EPC or principal contractor delivery
• Balance-of-plant and construction management
• Integration with wider energy infrastructure programmes

4. Anesco

Anesco is active across the development and delivery of energy storage projects and is frequently referenced as an EPC provider for BESS installations in the UK market. Its involvement typically spans from construction through to operational handover.

Website: anesco.com

• EPC delivery of battery storage facilities
• Coordination of civils and BoP contractors
• Project delivery on commercial and grid-scale sites

5. Rossair

Rossair positions itself as a delivery partner for grid-scale battery storage projects, offering services that span feasibility, design, procurement, and construction. The company is relevant for principal contractors seeking partners with hands-on BESS construction experience.

Website: rossair.co.uk

• Civils and construction delivery for BESS sites
• Project coordination and buildability input
• Support from early works through to completion

6. G2 Energy (Mitie Power & Grid)

G2 Energy delivers high-voltage grid connections and associated balance-of-plant works for major energy infrastructure schemes, including BESS facilities.

Website: g2energy.co.uk

• HV and grid-connection works
• Electrical balance-of-plant delivery
• DNO and transmission interface coordination

7. Omexom (VINCI Energies)

Omexom is an energy infrastructure contractor with experience across substations, grid connections, and energy storage facilities, supporting BESS projects requiring complex electrical integration.

Website: omexom.co.uk

• Electrical infrastructure and grid integration
• Substation-adjacent construction works
• Multi-disciplinary delivery coordination

8. Ethical Power

Ethical Power delivers renewable energy and storage projects across the UK and positions itself as an EPC and balance-of-plant delivery partner for BESS developments.

Website: ethical-power.com

• EPC or principal contractor delivery
• Balance-of-plant and electrical works
• Civils and grid interface coordination

9. H&MV Engineering

H&MV Engineering specialises in HV and EHV substations and grid infrastructure, playing a critical delivery role on transmission-connected BESS projects.

Website: hmvengineering.com

• HV and EHV substation delivery
• Grid-connection infrastructure works
• Electrical integration for BESS facilities

10. Excalon

Excalon operates as a turnkey infrastructure contractor delivering design, construction, and installation services across energy projects, including battery storage developments.

Website: excalon.co.uk

• Turnkey construction delivery
• Civil and electrical works
• Site coordination and programme control

11. Green Frog Connect

Green Frog Connect operates as an independent connection provider delivering grid connections and electrical infrastructure for energy projects including BESS facilities.

Website: greenfrogconnect.com

• Grid-connection works as ICP
• Electrical balance-of-plant delivery
• DNO and transmission coordination

12. Advance Grid Solutions

Advance Grid Solutions delivers turnkey electrical and grid infrastructure works combining civils, cabling, and electrical delivery for energy projects.

Website: advancegridsolutions.co.uk

• Civil and electrical construction
• Grid-connection delivery
• Balance-of-plant coordination

13. Metlen (formerly Mytilineos)

Metlen operates internationally as an EPC contractor for large-scale energy infrastructure projects, including battery storage developments in the UK.

Website: metlengroup.com

• EPC delivery of large-scale BESS
• Construction management and integration
• Coordination of civils and electrical scopes

14. Belectric (UK)

Belectric delivers utility-scale renewable energy projects and is active in the construction of battery storage facilities, often alongside solar developments.

Website: belectric.com

• EPC or construction delivery
• Balance-of-plant and site works
• Integration within wider energy assets

15. Edina

Edina is active in the delivery of energy storage and generation infrastructure, positioning itself as a system integrator and EPC delivery partner.

Website: edina.eu

• EPC or system integration delivery
• Construction and installation coordination
• Commissioning and handover support

16. Sirius Group

Sirius Group delivers civil engineering and balance-of-plant works across renewable and energy infrastructure projects, including BESS sites.

Website: sirius-group.co.uk

• Civils and groundworks for BESS compounds
• Balance-of-plant construction
• Site access and hardstanding works

17. ACS Construction Group

ACS Construction Group positions itself as a construction delivery partner for battery energy storage projects across the UK.

Website: acsconstructiongroup.com

• Construction delivery for BESS sites
• Civils and structural works
• On-site coordination support

18. Fluence

Fluence operates as a battery storage system integrator and is frequently involved in the delivery phase of large BESS projects alongside EPCs and principal contractors.

Website: fluenceenergy.com

• Battery system integration
• Coordination with EPC and construction teams
• Commissioning and handover support

19. Elements Green

Elements Green is a UK-based energy developer responsible for several large grid-scale BESS schemes and appoints principal contractors and grid specialists for delivery.

Website: elementsgreen.com

• Project development oversight
• Appointment of delivery partners
• Grid-connection programme coordination

20. Field

Field develops and operates utility-scale battery energy storage projects across the UK, working with appointed principal contractors for construction delivery.

Website: field.energy

• Developer-led project delivery
• Appointment of principal contractors
• Programme coordination through construction

21. NHOA Energy

NHOA Energy operates as a turnkey EPC and system integration partner for large-scale energy storage projects.

Website: nhoa.energy

• Turnkey EPC delivery
• Battery system integration
• Commissioning and performance handover

22. Omexom (VINCI Energies)

Omexom supports BESS projects requiring complex electrical integration alongside construction delivery.

Website: omexom.co.uk

• Electrical infrastructure delivery
• Grid and substation integration
• Multi-disciplinary coordination

23. H&MV Engineering

H&MV Engineering delivers HV and EHV infrastructure critical to transmission-connected BESS projects.

Website: hmvengineering.com

• HV and EHV substation delivery
• Grid-connection infrastructure
• BESS electrical integration

24. Advance Grid Solutions

Advance Grid Solutions provides integrated civil and electrical delivery for grid-connected BESS schemes.

Website: advancegridsolutions.co.uk

• Civil and electrical construction
• Grid-connection delivery
• Balance-of-plant coordination

25. G2 Energy

G2 Energy delivers HV grid connections and electrical infrastructure for large-scale BESS and energy projects.

Website: g2energy.co.uk

• HV and grid-connection works
• Electrical balance-of-plant delivery
• DNO and transmission coordination

How BESS sites are typically delivered

Most UK BESS projects involve overlapping scopes including civils, balance-of-plant works, battery container installation, and HV grid connections. Delays most commonly occur at interfaces, particularly between civils readiness, battery delivery, and grid connection sequencing.

Common delivery risks on BESS projects

• Grid connection dates moving after civils are complete
• Battery containers arriving before compounds are build-ready
• Insufficient crane access or hardstanding
• Late discovery of earthing or containment clashes
• Temporary site infrastructure failures impacting programme

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