Over all tracts and all residential buildings in the United States, the estimated residential rooftop solar technical potential is nearly 1,000 TWh of generation, or about 75 percent of residential consumption. A majority of the overall residential potential (683 TWh, 68.4 percent) is situated on single-family buildings, as compared to multi-family dwellings (316 TWh, 31.6 percent).

Although low-to-moderate income (LMI) households represent about 43 percent of the U.S. population, a new report (»Rooftop Solar Technical Potential for Low-to-Moderate Income Households in the United States«) released by the National Renewable Energy Laboratory (NREL) shows that nearly half of all the United States’ residential rooftop solar technical potential is on the dwellings LMI households, representing 320 GW of potential solar capacity. Although residential solar adoption has increased over the past decade, adoption among LMI households and affordable housing providers continues to lag. LMI households are defined as 80 percent or less of the Area Median Income.

Main research questions of the NREL study are: (1) What is the quantity and spatial distribution of rooftop technical potential, stratified by income, building type, and tenure? (2) Among low-to-moderate-income households, what is the feasibility of achieving parity in solar access across income groups? Compared to high-income households, LMI households disproportionately live in rental-occupied, multi-family buildings. Because of principal-agent issues in solar adoption, there are significant economic and regulatory barriers inhibiting the installation of solar equipment on buildings occupied by LMI households. (3) Finally, low- and moderate-income households interact with a vast web of nonprofit entities, e.g., places of worship and public schools. What is the quantity of technical potential for these classes of buildings, and to what extent might these buildings oversize systems on their roofs to export excess generation to LMI households?
The report, which includes an interactive map, is part of a three-year research project led by the National Renewable Energy Laboratory. The project was funded by the Department of Energy’s Solar Energy Evolution and Diffusion Studies (SEEDS) program. The report »Rooftop Solar Technical Potential for Low-to-Moderate Income Households in the United States« (71 pages) is available free of charge at the NREL website.