Energy storage power station setback distance

What are the risks associated with battery energy storage systems (Bess)?

For Battery Energy Storage Systems (BESS), the risk to Transpower’s assets is fire and associated smoke, both of which can damage national grid assets and cause outages. Simply placing BESS outside the NGY may not be sufficient in the event of a fire, so specific setbacks values for BESS have been developed (see Table 1).

Why do we need a setback from the National Grid?

Having an appropriate setback from the National Grid has important safety benefits such as preventing damage to property and risk of harm to people. For Battery Energy Storage Systems (BESS), the risk to Transpower’s assets is fire and associated smoke, both of which can damage national grid assets and cause outages.

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 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 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.