Energy storage equipment spacing requirements

What is the minimum spacing between ESS units?

A minimum spacing of 3 feet is required between ESS units unless 9540A testing allows for closer spacing. ESS location requirements are detailed for areas including garages, accessory structures, utility closets, and outdoors. ESS installed outdoors may not be within 3-feet of doors and windows.

How much energy can a ESS unit store?

Individual ESS units shall have a maximum stored energy of 20 kWh per NFPA Section 15.7. NFPA 855 clearly tells us each unit can be up to 20 kWh, but how much overall storage can you put in your installation? That depends on where you put it and is defined in Section 15.7.1 of NFPA 855.

How far apart should storage units be positioned?

Therefore, if you install multiple storage units, you have to space them three feet apart unless the manufacturer has already done large-scale fire testing and can prove closer spacing will not cause fire to propagate between adjacent units.

How far should ESS units be separated from each other?

In Section 15.5 of NFPA 855, we learn that individual ESS units shall be separated from each other by a minimum of three feet, unless smaller separation distances are documented to be adequate and approved by the authority having jurisdiction (AHJ) based on large-scale fire testing.

What is the maximum energy rating per ESS unit?

The maximum energy rating per ESS unit is 20 kWh. The maximum kWh capacity per location is also specified—80 kWh when located in garages, accessory structures, and outdoors and 40 kWh in utility closets or storage spaces. For storage capacities that exceed these limits, non-residential requirements come into play (NFPA 855 Chapters 4-9).

What are the fire and building codes for energy storage systems?

However, many designers and installers, especially those new to energy storage systems, are unfamiliar with the fire and building codes pertaining to battery installations. Another code-making body is the National Fire Protection Association (NFPA). Some states adopt the NFPA 1 Fire Code rather than the IFC.