Generation from small scale solar systems in the United States, mostly rooftop installations smaller than one megawatt, has increased from 18,812 gigawatt hours to 92,979 gigawatt hours over the last decade, the Energy Information Administration estimated in its latest Today in Energy analysis. The four largest producing states, California, Arizona, Texas and Florida, sit in regions with abundant solar resources, while New York ranks fifth on capacity growth supported by technology improvements and state incentives.
California accounted for 37 percent of national small scale generation in 2025, some 34,411 gigawatt hours, and its rooftop output grew 8 percent between 2024 and 2025 as capacity rose from 18 gigawatts to 20 gigawatts. The fastest single year in the series was 2022, when generation grew 25 percent amid record capacity additions, helped by installers rushing to qualify under California’s Net Energy Metering 2.0 terms before the less generous Net Billing Tariff took effect in April 2023, with earlier capacity grandfathered under the old rules.
For fuel markets the significance is displacement at the margin. Every additional rooftop gigawatt hour is a gigawatt hour the grid does not buy from gas fired generation in daylight hours, and at nearly 93,000 gigawatt hours a year the small scale fleet is now a structural feature of US power balances rather than a rounding item.