Safety

Key Updates in Residential & Portable Battery System Requirements

UL 9540 & UL 9540A: Covers 20kWh energy storage systems ESS, with 9540A providing large-scale fire testing to assess risks in residential settings. 2025 update includes more stringent gas and temperature testing.

UL 9540B: A newer protocol for large-scale fire testing of residential ESS. Not currently required.

UL 2743: Specifically for portable power packs (units must be 20kWh), ensuring device-level safety for portable, non-grid use.

NFPA 855: Sets installation rules, becoming stricter in 2025 limiting total stored energy and placement (garages, outdoors, utility spaces, e.g. 10kWh per dwelling and 1kWh if interior portable system) to manage fire hazards, with specific protection (gypsum board) required for unfinished indoor spaces.

Source: BSLBATT, NFPA, UL Solutions

Extracted from the PDF; charts and images may read imperfectly.