There are requirements for the spacing between energy storage containers

What does NFPA 855 mean for energy storage systems?

Specifically, we’re focused on spacing requirements and limitations for energy storage systems (ESS). NFPA 855 sets the rules in residential settings for each energy storage unit—how many kWh you can have per unit and the spacing requirements between those units.

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.

What is the standard for installation of stationary energy storage systems?

“Standard for the Installation of Stationary Energy Storage Systems.” CFC Section 1206.2.8.3 Stationary Battery Arrays Stationary battery arrays shall be spaced not less than 3 ft from other stationary battery arrays.

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 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.