What changed in the batteries going into the grid
A battery energy storage system takes electricity from the grid or a power plant, holds it, and releases it later when it is needed. Five years ago most new ones used a nickel based lithium ion chemistry. That has flipped. Lithium iron phosphate, a chemistry that swaps out the nickel and cobalt for iron, held well below 50% of new battery storage installed worldwide then, the International Energy Agency states. By 2023 it reached 80% of new storage. It is now around 90%, the agency reports in its newest review.
The market this happened in grew fast too. Worldwide, 108 gigawatts of new battery storage went in during 2025, 40% more than the year before, and installed capacity is now 11 times higher than it was in 2021, the agency states. China alone built around 60% of the 2025 total, and 80% of everything added that year was a utility scale system rather than a home or business battery.
The International Energy Agency states installed battery storage capacity worldwide is now 11 times higher than in 2021. The 2021 bar is set to 1 as the starting point for that comparison, it is not a separate measured figure from the source.
Show the numbers
| 2021 | 1 |
| Now | 11 |
Storage picked the chemistry for cost, not for fire
The agency gives the plain reason storage moved to this chemistry. It costs less, needs no nickel or cobalt, and stands up to more charging and discharging cycles before it wears out. Lower fire risk comes with it, but only as a relative gain. The agency states the chemistry has, in its own words, "even lower flammability and a longer lifetime" than the nickel based kind, not that it cannot catch fire at all.
There's a good chance that all stationary storage that is Powerwall and Megapack moves to iron.
Elon Musk, chief executive of Tesla, speaking on the Tesla investor call held in 2021. Source 5.
What proved the fire risk was real
The fires that forced a change both happened in the older, nickel based chemistry, not the newer one. On May 15, 2024, a facility holding about 15,000 nickel manganese cobalt batteries in San Diego caught fire, with flare ups continuing for 7 days. On January 16, 2025, a nickel manganese cobalt facility in Moss Landing, California caught fire and forced a 24 hour evacuation of about 1,200 nearby residents. No source used for this article records a major fire in a lithium iron phosphate grid battery.
Counts come from an Electric Power Research Institute database reproduced by the federal regulator. The rate of incidents per gigawatt hour deployed fell over this period even though the yearly count above did not fall in a straight line, because worldwide deployment grew far faster than incidents did.
Show the numbers
| 2018 | 16 |
| 2019 | 14 |
| 2020 | 4 |
| 2021 | 11 |
| 2022 | 13 |
| 2023 | 15 |
| 2024 | 8 |
California put the fire department in the approval process
California answered with a law. Senate Bill 283, signed by Governor Newsom on October 8, 2025 and effective January 1, 2026, requires a developer to consult local fire authorities before filing an application, requires a safety inspection before a facility can switch on, puts the cost of that inspection on the facility owner, and restricts building inside combustible structures.
California must prioritize safety at every step when expanding battery storage to meet its clean energy goals.
John Laird, California state senator, author of Senate Bill 283. Source 4.
The law does not ban a chemistry. It puts the local fire department inside the approval and inspection of a project, whichever chemistry the next developer proposes.