Chart: More and more rooftop solar buyers are adding home batteries

The uptick in home battery installations is yet another sign that the era of battery storage has arrived in the U.S.

Batteries are all the rage — especially among homeowners who are going solar.

The percentage of people who install a battery alongside their new rooftop solar system is surging in the U.S., according to a new report from Lawrence Berkeley National Laboratory.

That figure — known as the residential attachment rate — jumped from just under 10 percent in 2022 to 12.3 percent last year. This year, energy research firm Wood Mackenzie estimated that it will soar to 25 percent.

The surging interest in home batteries — which are almost always purchased to store power from solar arrays — comes as the country’s rooftop solar market craters. Installations are expected to fall by 19 percent this year, according to the Solar Energy Industries Association.

Policy changes in California, the nation’s biggest residential solar market by far, have a lot to do with both the contraction of the rooftop solar market and the rising popularity of home batteries. In April of last year, changes to the Golden State’s net-metering program took effect, slashing the rate at which rooftop solar owners could sell surplus power to the grid but boosting the value of batteries, which enable homeowners to save their solar power for the times when it’s most valuable. The overall attachment rate in California was 14 percent in 2023, but that figure surged to well over 20 percent by the end of the year following the state’s policy changes.

But other factors are driving the uptick in home battery installations as well. Extreme weather events, made more frequent by climate change, are increasingly threatening grid reliability. Batteries are becoming more affordable. And rising utility rates are making the economics of solar-plus-storage more attractive to homeowners.

The latter is certainly a factor in Hawaii, the state with by far the highest residential attachment rate in 2023 — 95 percent — and the only one with electricity rates higher than California’s. Hawaii had a generous and highly successful battery incentive program running for all of last year, which it has since walked back.

Whatever the reasons for the rising popularity of home batteries in the U.S., the implication is clear: It’s yet another sign that the era of battery storage has arrived. Big, utility-scale battery projects are being built across the nation at a rate that would have been hard to fathom just a few years ago. The new LBNL data shows that a similar trend is underway for home battery systems too.