Consulting Areas

Residential Energy Storage System Fire Investigation

We typically respond within one business day.

Fires Involving Home Battery Systems

A residential energy storage system (ESS) is a home battery system, usually lithium-ion, that stores power from rooftop solar or the grid for use later or during an outage. Most include battery modules, an inverter or other power conversion equipment, a battery management system, and the wiring, disconnects and breakers that connect them to the home’s electrical system. When a fire involves one, the question is whether the battery system started it, whether the installation or the home’s wiring did, or whether the system was damaged by a fire that started somewhere else.

Our licensed Professional Engineers investigate fires involving home battery systems, their inverters and their solar connections for insurers, adjusters, subrogation counsel, attorneys and homeowners, and examine the evidence at our engineering lab in Coldspring, Texas.

Submit an assignment or contact us for a free quote. We typically respond within one business day.

How We Investigate a Home Battery Fire

We get to the scene as soon as possible and document it as found, including the battery system, the inverter, the disconnects and the panel it connects to, and the garage, utility room or exterior wall where it was installed. Our investigations follow a systematic approach consistent with NFPA 921: the fire patterns lead back to an area of origin, and each potential ignition source in that area is tested against the physical evidence. We evaluate:

Battery modules and cells: evidence of an internal failure, physical damage, water intrusion or overheating.
The battery management system: the controls that monitor cell voltages and temperatures and are meant to keep the battery within its operating limits.
The inverter and power conversion equipment: the equipment that connects the battery to the solar array, the home and the grid.
Installation and wiring: conductor sizing, terminations, overcurrent protection, disconnects and the connection to the home’s panel, including loose or overheated connections.
The location: clearances, ventilation and nearby combustibles, and whether the system was exposed to heat, water or vehicle impact.
Other sources in the area of origin: the home’s own wiring, appliances and other equipment, since an ESS can be damaged by a fire that started elsewhere.

Thermal runaway in a lithium-ion cell is a self-heating reaction that releases flammable gases and can spread from cell to cell. It can be started by a defect, physical damage, an electrical fault or heat from a fire outside the battery, so a battery that went into thermal runaway didn’t necessarily start the fire.

Evidence is collected under a protocol agreed with the interested parties, kept in video-monitored storage and examined at our engineering lab in Coldspring, Texas. Non-destructive examination comes first; destructive steps wait until the interested parties have had the chance to attend, and joint lab examinations are arranged when other parties need to attend.

Product, Installation or Something Else

A fire involving a home battery system often comes down to whether the product failed, whether it was installed incorrectly, or whether something else caused it. Part of that answer is whether the system was listed and installed the way its listing, the manufacturer’s instructions and the codes in force required. We look at:

Listing: UL 9540 is the safety standard for energy storage systems and equipment, and codes in many jurisdictions require a residential ESS to be listed to it. We check the listing and the manufacturer’s installation instructions for the equipment involved.
Installation requirements: NFPA 855, Standard for the Installation of Stationary Energy Storage Systems, and the electrical and residential codes address how a home system can be installed, such as allowed locations, limits on stored energy and spacing between units. Which edition applies, if any, depends on what the jurisdiction had adopted when the system was installed.
Permits and inspections: whether the installation was permitted and inspected, and whether the work matched the approved plans.
Records: the installer’s design and as-built documents, commissioning records, monitoring and event data where the system recorded it, firmware and service history, and any recall or service notices.

A missed listing or code requirement doesn’t by itself mean that condition caused the fire; the physical evidence has to connect it to the origin. Not every home battery fire leads back to the manufacturer or the installer, and an early, well-documented examination is what lets an insurer or attorney decide whether a subrogation claim is worth pursuing.

Fire line do not cross tape at a fire scene

What to do first after a home battery fire

A damaged battery can reignite after the fire appears to be out, and it can still hold stored energy. Let the fire department and the installer or a qualified electrician make the system safe, and don’t restart, reset or take apart equipment beyond what safety requires. If the system has to be disconnected, record who did it and how.

Leave the battery, inverter, disconnects and panel in place until they have been documented. Keep the installer’s paperwork, the permits, the owner’s manual and access to the monitoring app. Notify the interested parties, such as the battery and inverter manufacturers and the installer, before anything is moved, so they have the chance to attend.

Our fire investigations are led by licensed Professional Engineers with active and past licensure in multiple states. Brian J. Brackensick, M.S., P.E. and Stepan V. Eero, M.S., P.E. are NAFI Certified Fire and Explosion Investigators (CFEI) and Certified Vehicle Fire Investigators (CVFI).

Our engineers write expert reports and testify in depositions and at trial.

When you contact us, you talk directly with an engineer who can discuss your loss. Our offices are in Coldspring, Texas and Westcliffe, Colorado, and we work nationwide. Reports are PE-stamped where required, and we also accept consulting-only (non-testifying) retentions.

Submit an assignment, call us at 866-621-6920 or contact us for a free quote. We typically respond within one business day.

Frequently Asked Questions

Can a home battery fire reignite?

Yes. A damaged lithium-ion battery can reignite after the fire appears to be out, and it can still hold stored energy. Leave the system to the fire department and people qualified to make it safe, and keep the area clear until they have.

Does a home battery have to meet UL 9540 and NFPA 855?

That depends on the codes the jurisdiction had adopted when the system was installed. Many jurisdictions require a residential ESS to be listed to UL 9540 and installed under rules drawn from NFPA 855 or the residential code. For an investigation, the question is not only whether a requirement applied, but whether the condition it addresses had anything to do with the fire.

Should the manufacturer and the installer be notified?

Yes, before the system is moved, taken apart or discarded, so they have the chance to attend the examination. Giving every interested party that chance helps avoid spoliation disputes later.

What records should be kept after a home battery fire?

The installation contract, design and as-built documents, permits and inspection records, commissioning records, the owner’s manual, utility interconnection paperwork, service history, recall notices, and access to the system’s monitoring app or account.