U.S. Natural Renewable Energy Laboratory epub Rooftop Solar Photovoltaic Technical Potential in the United States: A Detailed Assessment

This report quantifies the technical potential of photovoltaic (PV) systems deployed on rooftops in the continental United States, estimating how much energy could be generated by installing PV on all suitable roof area. The results do not exclude systems based on their economic performance, and thus they provide an upper bound on potential deployment rather than a prediction of actual deployment. Although methods have been developed to estimate rooftop PV technical potential at the individual building level, previous estimates at the regional and national levels have lacked a rigorous foundation in geospatial data and statistical analysis. This report helps fill this gap by providing a detailed data-driven analysis of U.S. (national, state, and ZIP-code level) rooftop PV availability and technical electricity-generation potential. First, we use light detection and ranging (lidar) data, geographic information system (GIS) methods, and PV-generation modeling to calculate the suitability of rooftops for hosting PV in 128 cities nationwide—representing approximately 23% of U.S. buildings—and we provide PV-generation results for a subset of these cities. Second, we extend the insights from this analysis of areas covered by lidar data to the entire continental United States. We develop two statistical models—one for small buildings and one for medium and large buildings—that estimate the total amount of roof area suitable for hosting PV systems, and we simulate the productivity of PV modules on the roof area to arrive at the nationwide technical potential for PV. Our analysis of the trends in the suitability of rooftops for hosting PV systems reveals important variations in this key driver of rooftop PV technical potential that have not been captured by previous approaches. Figure ES-1 shows the results—from our statistical modeling grounded in lidar data—for the percentage of small buildings that are suitable for PV in each ZIP code in the continental United States. In the figure we can identify regional trends in the suitability of small building rooftops, with high densities of suitable small buildings in California, Florida, and the West South Central census division. Such trends are also critical to estimating PV technical potential at finer resolution, and our report illustrates this with a high-resolution analysis of 11 representative cities.