CGM Group was commissioned to undertake a detailed fire risk assessment for a co-located solar PV and Battery Energy Storage System (BESS) installation where multiple stakeholders—including separate asset owners for the PV and BESS elements, a shared grid connection operator, and an independent O&M contractor—created complex operational interfaces that needed to be clearly understood and managed.

The assessment was structured around the Regulatory Reform (Fire Safety) Order 2005 framework, adapted to address the unique hazard profile of a renewable energy site incorporating lithium-ion battery storage. We carried out a physical site inspection covering the PV array, inverter stations, BESS enclosures, switchgear compound, cable routes, and boundary conditions including neighbouring land use and vegetation management.

Our fire risk identification considered both conventional ignition sources—such as DC arc faults in PV string cabling, AC switchgear failures, and transformer oil releases—and BESS-specific scenarios including thermal runaway propagation, off-gas ignition, and re-ignition following initial suppression. Particular attention was paid to the separation distances between BESS containers, between BESS and PV inverter stations, and between energy infrastructure and the site boundary, benchmarking the as-built layout against NFPA 855 and the UL 9540A test data provided by the battery system manufacturer.

We reviewed the fire detection and suppression philosophy for each zone of the site, evaluating whether detection technologies (e.g., off-gas sensors, linear heat detection, smoke and flame detectors) were appropriate for the specific fire dynamics expected. The adequacy of suppression systems—including clean-agent systems within BESS enclosures and the availability of sufficient water supply for external cooling by the fire service—was assessed against credible fire duration and heat release rate estimates.

Access and egress were evaluated for both routine maintenance and emergency response scenarios. We identified pinch points where simultaneous PV and BESS maintenance activities could compromise safe evacuation, and where fire service appliance access was constrained by cable trenches, security fencing, or terrain.

The deliverable was a prioritised recommendations register with each measure categorised as essential, recommended, or advisory, along with indicative implementation timescales and responsible parties. Key recommendations included revising the site emergency plan to reflect multi-stakeholder coordination protocols, installing additional fire-break vegetation management zones, upgrading signage and isolation point labelling to assist emergency responders unfamiliar with the site, and establishing a shared incident notification procedure between the PV and BESS operators.

The assessment was presented in a joint stakeholder workshop, enabling all parties to agree on ownership of each recommendation and establish a shared action tracker. The resulting alignment significantly reduced the time required to finalise the site's operational safety case and gave both asset owners a stronger position in their respective insurer negotiations.

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