Are home batteries safe?

Rarely, but nobody tracks it well in the U.S. EPRI's battery failure database, the main public record, covers utility-scale and commercial systems and notes that residential failures aren't tracked. One German study published in 2024 estimated the chance of a home storage fire at about 0.005%, roughly 50 times lower than for a house fire in general; treat that as a rough estimate from another country.

When a battery does fail, it can be serious. In tests at UL's Fire Safety Research Institute in Northbrook, batteries in thermal runaway released flammable gas that could ignite later, and the garage door was the weakest part of the structure. The U.S. Fire Administration's advice: don't try to put out a lithium-ion battery fire. Get out and call 911.

Lithium iron phosphate (LFP). A 2024 peer-reviewed study ranked the thermal runaway danger of common lithium-ion chemistries, from most to least dangerous, as LCO, NCA, NMC and then LFP, well behind the others. LFP is harder to push into thermal runaway and burns less intensely, but it isn't fireproof: it can still overheat and vent gas.

See Powerwall 3 vs. Enphase vs. FranklinWH for how they compare on cost and backup.

• UL 9540. The listing for the whole system, the battery and its inverter tested together. UL says the model installation codes all require it. Ask for the UL 9540 listing on the exact combination you're buying.
• UL 9540A. A fire test method, not a pass-or-fail listing. Codes use its results to allow closer spacing or more capacity in one spot.
• UL 1973. Covers the battery pack or module only. On its own, it isn't enough.

Where your town's code allows. The national residential rules most towns follow, from the International Residential Code and NFPA 855, generally:

• Allow batteries in garages, outdoors or on exterior walls, and in utility closets, basements and storage spaces with finished walls
• Bar them from bedrooms and from closets or spaces that open into a bedroom
• Cap each unit at 20 kWh, and total capacity at about 40 kWh in utility closets and basements and 80 kWh in a garage, on an exterior wall or outdoors
• Require smoke alarms (or a linked heat detector) where the battery sits, and barriers if a car could hit it

Illinois has no single statewide residential code for existing homes, so the edition and any local changes depend on your city or village. Chicago uses its own construction codes, and its fire code requires a construction permit for stationary battery systems. Your installer should confirm the local rules and pull the permit. See what a home battery can run in an outage.

Usually as part of the house, but ask before you install. We haven't found Illinois-specific guidance, and insurers don't publish battery surcharges. Tell your insurer about the battery, confirm it's covered under your dwelling coverage, raise your dwelling limit if the system adds real value, and ask about equipment-breakdown coverage, which some insurers now offer for home batteries. Not telling your insurer about solar can limit a claim payout, and the same logic applies to a battery. See solar and homeowners insurance in Illinois.

They happen, and staying connected helps. In November 2025, more than 10,500 Tesla Powerwall 2 units sold from November 2020 to December 2022 were recalled for fire risk after 22 overheating reports, including five fires with minor property damage and no injuries. Tesla remotely discharged affected systems that were online. LG Energy Solution recalled RESU 10H home batteries in 2020 and 2021 and later fixed affected units with a remote software update.

Keep your battery connected to Wi-Fi or cellular so it can receive safety updates, register its serial number with the manufacturer, and check the U.S. Consumer Product Safety Commission's recall list if you buy a home that already has a battery. See buying a house with solar.