Owner's Engineer BESS UK: Independent Owner’s Engineer for a 120 MW Grid-Scale Battery Energy Storage Project (UK)

Client Context
A UK infrastructure developer progressing a 120 MW / 240 MWh battery energy storage project to Final Investment Decision (FID). The project was being delivered under a lump-sum EPC contract using a tier-1 integrator and multiple OEM packages.

Challenge
The client required independent assurance that EPC design decisions optimised long-term operability and owner risk, not just construction cost and programme. Particular concerns included container structural margins, thermal management assumptions, and access for future battery replacement.

What we did
Equitus was appointed as Independent Owner’s Engineer prior to FID to review the EPC technical baseline.

Scope included:

• EPC design challenge and technical compliance review

• Structural assessment of container and plinth systems

• Thermal management validation under worst-case UK summer scenarios

• Review of maintenance access and battery swap-out strategy

Outcome

• Identified multiple design assumptions that would have constrained future repowering

• Enabled design refinements prior to contract freeze, avoiding post-COD remediation

• Reduced lender technical queries during FID process

Value to Asset Owner
Lower lifecycle risk, improved maintainability, and stronger confidence at financial close.