Residential energy storage systems (ESS) using lithium-ion batteries can present safety challenges for homeowners and firefighters. While the failure of residential ESS lithium-ion batteries is a rare event, fire and explosion hazards have already occurred. This guide provides steps homeowners and ESS installers can take to minimize these hazards. ESS are electrical devices that can pose shock hazards when in unsafe conditions, such as when wet or damaged. Like laptops, cellular phones, e-bikes, electric vehicles and power tools, residential ESS contain lithium ion batteries which can fail and experience thermal runaway. Thermal runaway failures result in rapid heating, ejection of hot material and the release of flammable and toxic gas, which can create fire and toxic gas/smoke hazards. Thermal runaway of all the lithium ion cells within a residential ESS unit can release a volume of flammable gas similar to a 20 lb propane tank, commonly used in backyard grilling. Thermal runaway also presents an explosion hazard if the resulting flammable gas accumulates in an enclosed space, and then ignites. The force from an explosion could cause bodily injury or death and property damage, including broken windows, structural compromise and the spread of debris. Fortunately, thermal runaway failures are unlikely. Homeowners and ESS installers can take simple actions to reduce both the likelihood and consequences of ESS failures.

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Safety Guidelines

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Install ESS systems from reputable manufacturers whose equipment is listed as certified to UL ¹ and UL ²

What to Install:

Installers should be licensed electricians

Who to install:

Installers should be certified by the ESS manufacturer

Make sure that ESS battery, inverter, controller and photovoltaic system components are compatible as recommended by all associated manufacturers

How to Install:

Installation should follow manufacturer’s instructions

Installation should be performed according to locally adopted building codes and standards. The most up-to-date common requirements are usually based on:

International Residential Code: Section R328 Energy Storage Systems³

NFPA 855: Standard for the Installation of Energy Storage Systems - Chapter 15⁴

Where to install:

What you can do:

Register your ESS with the manufacturer and connect it to WiFi to allow monitoring. Stay up to date on any firmware updates and safety recalls.

Have working smoke detectors. Check regularly and change the batteries as needed.

Check regularly to make sure that the manufacturer recommended clearance or 3’ feet of clearance is maintained. Remove objects and debris, especially flammable material.

Trim vegetation that may be growing near the ESS, especially close to the clearance zone.

Keep a fire extinguisher handy in your house. You will not be able to stop thermal runaway of your ESS. But if you can extinguish a non-ESS fire while it is small you can prevent the ESS and the rest of your house from becoming involved. DO NOT attempt to stop an ESS fire with a fire extinguisher.

In case of fire, smoke, gas, or chemical odor evacuate and call 911.

In case of abnormal behavior, damage or swelling of ESS equipment call technical support or qualified technicians.

[1] https://www.shopulstandards.com/ProductDetail.aspx?productId=UL_2_S_ [2] https://www.shopulstandards.com/ProductDetail.aspx?productId=UL_3_S_ [3] “Section R328 Energy Storage Systems,” in International Residential Code (IRC) | ICC Digital Codes, ICC, . Accessed: Jan. 31, . [Online]. Available: https://codes.iccsafe.org/content/IRCP2/chapter- 3-building-planning#IRCP2_Pt03_Ch03_SecR328 [4] “NFPA 855: Standard for the Installation of Stationary Energy Storage Systems.” https://www.nfpa.org/codes- and-standards/all-codes-and-standards/list-of-codes-and-standards/detail?code=855 (accessed Jan. 31, ) [5] “About the NEC” https://www.nfpa.org/nec/ (accessed May 9, )

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Prepared by:

Lakshmi Srinivasan

Senior Technical Leader

Erik Archibald, PhD, PE

Partner / Senior Engineer

NFPA 705: National Electrical Code⁵

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With competitive price and timely delivery, CHANGINGTECH sincerely hope to be your supplier and partner.

Install in a safe location

Outdoors (most preferred) Indoor in a detached garage Indoor in an attached garage

Mount ESS on non-flammable material, such as masonry, metal, gypsum, etc.

Follow manufacturer’s clearance recommendation or provide a minimum 3’ clearance around the ESS to allow for adequate cooling and prevent the spread of fire

These simple actions can reduce the likelihood and consequences of ESS hazards.

Avoid areas subject to flooding or water leaks from above Avoid areas subject to snow accumulation. Place outdoor ESS above typical maximum snow level

Avoid areas subject to interference from children, pets and wildlife Avoid areas subject to falling items

Avoid areas subject to accidental vehicle impact. If in a space with vehicles, put bottom of ESS above hood level or install barriers to prevent impact.

Avoid areas subject to temperature extremes, such as south-facing walls in hot climates. Do not place near heating equipment

Avoid proximity to flammable vegetation or other flammable materials

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EPRI Hillview Avenue, Palo Alto, California - USA • 800.313. • 650.855. • • www.epri.com © Electric Power Research Institute (EPRI), Inc. All rights reserved. Electric Power Research Institute, EPRI, and TOGETHER…SHAPING THE FUTURE OF ENERGY are registered marks of the Electric Power Research Institute, Inc. in the U.S. and worldwide.

Stephanie Shaw, PhD

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Electrical and shock hazards can be avoided through careful design and protection against water and dust intrusion.

Battery failures can result in fire and explosion hazards. They can be avoided by taking proper precautions.

Physical impact from a vehicle or by dropping can cause battery failure and potentially lead to a fire. Use qualified installers and maintain a clearance zone around the battery.

Stored energy of any kind is a hazard. In the case of abnormal operation, damage, or swelling, immediately contact a qualified technician or the manufacturer.

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Residential Energy Storage System (ESS) Information and Resources

Welcome to the Woodland Fire Department's resource page for Residential Energy Storage Systems (ESS). As the use of renewable energy grows, ESS has become an essential component for homeowners looking to store energy efficiently and enhance sustainability. This page provides important guidelines and resources for community members considering the installation of ESS in their homes.

What is a Residential Energy Storage System (ESS)?

An ESS allows homeowners to store electricity generated from renewable sources, such as solar panels, for use during peak hours or power outages. This promotes energy independence, reduces reliance on the grid, and can lower energy costs.

Fire Hazards Associated with Residential Energy Storage Systems (ESS) and Lithium-Ion Batteries

Residential Energy Storage Systems (ESS), particularly those using lithium-ion batteries, can pose fire hazards if not properly installed, maintained, or monitored. Lithium-ion batteries store significant amounts of energy, and under certain conditions, such as overheating, physical damage, or manufacturing defects, they can experience thermal runaway—a dangerous reaction leading to fires or explosions.

Thermal runaway is a situation where a lithium-ion battery gets too hot, leading to a dangerous chain reaction. It starts when one part of the battery gets overheated, which causes it to release energy that heats up other parts of the battery. As the heat builds up, it can cause the battery to catch fire or even explode.

In a residential energy storage system, this could happen if the battery is damaged, improperly installed, or if there's a fault in the system. It's why proper installation, regular maintenance, and monitoring are so important—these steps help prevent the battery from getting too hot in the first place. If you ever notice your battery getting unusually hot or hear any strange noises, it’s important to turn off the system and contact a professional immediately.

What can homeowner's do to maintain their ESS once installed?

Once an Energy Storage System (ESS) is installed, homeowners can take several steps to maintain it and ensure fire safety:

1. Regular Inspections: Check the system periodically for any visible signs of damage, such as frayed wires, corrosion, or unusual noises. Have a professional inspect it annually to ensure it's functioning properly.
2. Keep the Area Clean: Maintain a clutter-free space around the ESS, ensuring proper ventilation and reducing the risk of overheating. Avoid storing flammable materials near the system.
3. Monitor System Performance: Use the ESS monitoring app or system dashboard to track battery performance. Pay attention to any warnings or alerts and address them promptly.
4. Update Software: Keep the ESS software up to date. Manufacturers often release updates that improve safety features and performance.
5. Ensure Proper Ventilation: Make sure the ESS location has adequate ventilation to prevent overheating. Follow manufacturer guidelines for spacing and placement.
6. Check Emergency Shutoff: Know where the system's emergency shutoff is located, and ensure it's accessible in case of an emergency.
7. Maintain Temperature Control: Monitor the environment around the ESS and keep the temperature within the manufacturer’s recommended range. Extreme heat or cold can affect the system's performance and safety.
8. Professional Servicing: If any issues arise or if maintenance is needed, contact a certified professional to handle repairs. Do not attempt to fix issues yourself.

By following these steps, homeowners can help ensure the long-term safety and efficiency of their Energy Storage System.

If you want to learn more, please visit our website Residential ESS Manufacturer.