To help consumers quantify the potential benefits of going solar, national laboratories and private companies have developed a number of tools.
National rooftop solar potential represents the absolute upper limit of photovoltaic deployment across the United States, determined by structural dimensions, orientation, shading, and geographic placement, without accounting for financial costs or equipment availability. According to a 2016 assessment by the National Renewable Energy Laboratory, the country contains upwards of 8 billion square meters of usable roof space capable of supporting more than 1 terawatt of generation capacity. Small-scale and residential structures account for roughly 65% of this total capacity, with low-to-moderate-income households making up 42% of those residential properties.
NREL data further indicates that approximately 3.3 million homes are constructed or undergo roof replacements annually, generating an estimated 30 gigawatts of yearly solar potential. Individual building potential is determined by tilt, construction materials, and regional irradiance, providing the foundation for estimates supplied to property owners by solar developers. To help consumers evaluate these installations, several federal laboratories and private companies have released evaluation tools supported in part by the U.S. Department of Energy’s Solar Energy Technologies Office.
EnergySage connects non-profit organizations, businesses, and homeowners with pre-screened installation professionals to generate address-specific estimates and allows users to compare system options using electricity bills. The National Renewable Energy Laboratory provides PVWatts, an online calculator for estimating energy generation and electricity costs for grid-tied photovoltaic setups globally using user data or online mapping. Another NREL program, the System Advisor Model, offers free techno-economic software to perform detailed financial and technical evaluations for renewable energy projects.
Sun Number assigns structures a suitability rating between 1 and 100 via aerial photography and algorithms that assess roof geometry, local weather, surrounding trees, and nearby structures. Through a collaboration with home-listing platform Zillow, these solar ratings have been integrated into property descriptions for over 40 million homes. Aurora Solar Inc. provides a web-based platform utilizing computer vision and image recognition to evaluate and contrast potential rooftop sites.
The Distributed Generation Market Demand model forecasts customer uptake of distributed energy technologies across industrial, commercial, and residential sectors through the year 2050. Folsom Labs created a permit-generation software engine that automates the creation of site plans, design specifications, single-line diagrams, and permit documents required by local authorities using its HelioScope engineering platform. The National Solar Radiation Database supplies hourly and half-hourly meteorological measurements alongside direct normal, global horizontal, and diffuse horizontal solar irradiance data.
Open-source software package PVLib enables performance simulations for photovoltaic installations through python and MATLAB versions maintained by an active user community. The Regional Energy Deployment System models investments in the power sector while factoring in system limitations, energy demand, and the technical and cost characteristics of renewable integration. REopt Lite evaluates resilience, cost savings, and performance targets to suggest optimal combinations of renewable energy, energy storage, and conventional power generation technologies.
Originally reported by Department of Energy (.gov) on Jul 16, 2026.
