The United States has enough usable rooftop space to deploy an amount of solar equal to its current nationwide generation levels, according to recent research on global photovoltaic potential. Researchers at Ireland’s University of Cork leveraged big data, machine learning, and geospatial analysis to reach their findings, which were published in Nature Communications.
In the report, about 77,000 square miles of rooftop area worldwide was demarcated as usable PV surface area (for context, the state of Florida is roughly 65,000 square miles). The researchers said this area could result the production of 27 petawatt-hours, or 27 million GWh, if completely covered by conventional photovoltaics.
This level of potential energy would exceed 2018 total global electricity consumption, a year in which 6 petawatt-hours (PWh) of electricity was consumed by homes alone, and over 23 PWh consumed in total globally, per Statista.com.
The report further said that rooftops in the United States could host enough capacity to produce an annual 4.2 PWh per year, effectively matching the nation’s current total energy output of about 4 PWh per year.
In 2020, about 60% of U.S. electric generation came from fossil fuels, and roughly 20% each from nuclear and renewable energy sources, according to data from the Energy Information Administration (EIA). EIA estimated that the U.S. additionally produced 42 billion kWh of electricity from distributed, small-scale solar, about 1% of total generation. Large-scale solar accounted for 2.2% of total generation that year.