Berkeley Lab: 37% of new US home solar systems came with a battery in 2025, up from 25%
Serguey Asael Shinder2 min readMore than a third of new residential solar systems installed in the United States in 2025 included a battery, according to the latest US distributed solar and storage data update from Lawrence Berkeley National Laboratory, reported by pv magazine on 3 October. The attachment rate was 37%, up from 25% in 2024.
The dataset. It covers about 5.3 million distributed solar and solar-plus-storage systems installed through the end of 2025, including about 450,000 installed during 2025, which Berkeley Lab estimates is 93% of that year's US distributed solar market.
California and everywhere else. In California, 74% of new residential systems included storage in 2025, up from 58% a year earlier. The state moved to its Net Billing Tariff, often called NEM 3.0, in April 2023, which cut the value of electricity that new rooftop customers export in many hours and made storing midday output more valuable. Outside California the change was faster in relative terms: across the other states in the comparison, the attachment rate rose from 7% to 17%. Berkeley Lab highlighted large increases in Arizona and Texas, and said Hawaii and California still have the highest rates. It did not attribute the rise outside California to any single factor.
Bigger output, not bigger batteries. The median residential battery held 13.5 kWh in both years. Median discharge capacity, the power a battery can deliver at once, rose from 6 kW to 11.4 kW, which Berkeley Lab attributed largely to wider deployment of the Tesla Powerwall 3.
Commercial roofs lag. Batteries were attached to 11% of non-residential solar installations in 2025, up from 7%. California's non-residential rate rose from 12% to 18%, and the rest of the country's from 4% to 8%.
What the figures leave out. The attachment rates count only batteries installed together with new solar. Batteries added later to existing systems and standalone home batteries are excluded, so the numbers measure how often installers pair the two, not total residential battery deployment.
What it means
Export tariffs are doing what they were designed to do: once the grid pays little for midday power, a solar sale increasingly becomes a solar-plus-battery sale. For distribution utilities, the jump in discharge power matters as much as the share. Homes that can deliver 11 kW at once are a larger resource for virtual power plants, and a larger load swing if they all respond to the same price signal.