UK Battery Storage Fire Safety and PAS 63100 Standards Guide

Key Takeaways

• PAS 63100:2024 was published on 20 March 2024 as the UK's dedicated fast-track standard for fire protection of domestic battery systems.
• The specification sets clear benchmarks for small-scale stationary secondary batteries installed in residential dwellings.
• Core requirements cover physical battery construction, battery management systems (BMS), power conversion equipment (PCE), and fail-to-safe controls.
• The standard's explicit goal is to prevent batteries from becoming an ignition source and to limit the consequences of a battery fire.
• Under statutory the 1989 Electricity at Work Regulations Regulation 4, all electrical systems must be constructed and maintained to prevent danger so far as is reasonably practicable.
• Regulation 5 dictates that equipment must never be put into use where its electrical strength or capability may be exceeded.

The Genesis of PAS 63100:2024

As residential battery energy storage systems (BESS) expanded rapidly across Great Britain to store solar generation and exploit cheap overnight tariffs, fire services noted rising risks associated with lithium-ion thermal runaway events in domestic properties.

To establish clear, nationally agreed specifications, the British Standards Institution (BSI) issued PAS 63100:2024:

• Designation: Fast-track Standard PAS 63100:2024 Electrical installations. Protection against fire of battery energy storage systems for use in dwellings. Specification.
• Publication: Formally published on 20 March 2024.
• Scope: Specifies requirements for fire safety in the installation of small-scale electrical battery energy storage systems (BESS) in domestic dwellings using stationary secondary batteries as the medium for energy storage.

Core Fire Safety Provisions and Component Architecture

PAS 63100 establishes strict engineering criteria across all hardware components forming the energy storage system:

1. Battery Units and Physical Isolation

Physical enclosures must incorporate thermal barriers to prevent cell-to-cell thermal propagation, non-combustible casing materials, and pressure relief vents to discharge off-gases safely.

2. Battery Management and Power Conversion

PAS 63100 defines fire safety requirements for:

• Physical requirements for battery units.
• Battery management systems (BMS).
• Power conversion equipment (PCE).
• Fault management and fail-to-safe operation of all control and monitoring functions.

3. Location and External Influences

The specification also covers installation requirements for installation location in respect of safety and external influences that affect fire safety, and protection against fire. Units must be protected from direct solar heat gain, physical vehicular impact, and flood risks.

Strategic Objectives: Ignition Prevention and Industry Benchmarking

National standardisation provides multiple industry and consumer benefits:

• Ignition Mitigation: The provisions in PAS 63100:2024 are intended to reduce the risk of batteries in dwellings becoming a source of ignition, and to limit the impact of a battery fire if one occurs.
• Installer Competence: It helps installers manage the fire safety related hazards associated with electrical energy (battery) storage systems in homes in the UK.
• Consumer Confidence: PAS 63100:2024 can help set a robust fire safety benchmark for small scale battery storage installations, increasing user confidence that systems will be safe and will function reliably, effectively and efficiently.

Statutory Underpinnings: the 1989 Electricity at Work Regulations and Premises Safety

Installers and system designers must ensure full compliance with primary UK safety legislation:

Electricity at Work Regulations 1989

• Regulation 4: All systems shall at all times be of such construction as to prevent, so far as is reasonably practicable, danger, and be maintained to prevent danger.
• Regulation 5: No electrical equipment shall be put into use where its strength and capability may be exceeded in such a way as may give rise to danger.

General Fire Precautions

Under Article 8 of the Fire Safety Order 2005, responsible persons must take such general fire precautions as may reasonably be required to ensure that premises are safe for relevant persons.

Furthermore, Historic England guidance on solar panels and paired storage has been updated to include advice on mitigating the risk of fire in historic homes.