The City of Cleveland and Cuyahoga County in Ohio are joining local governments around the globe in committing to 100% renewable energy goals by encouraging the use of solar technologies. Our team developed a method for estimating rooftop solar power potential using NASA Prediction of Worldwide Energy Resources (POWER) data to assist the City of Cleveland and Cuyahoga County with their renewable energy goals. POWER provides an estimate of incoming solar irradiation on a tilted surface by accounting for the light scattering and filtering effects of clouds and aerosols. Our methods improve on existing solar potential estimation tools through the inclusion of POWER data adjusted for roof slope, and a high-resolution (1 ft) digital surface model derived from LiDAR data, which allowed for detailed shadow, slope, and aspect modeling. To avoid overestimation, we calculated the solar potential for individual roof segments and removed those unsuitable for solar panel installation. We then applied our methods to a 5.38 square mile test area within the county and found a total rooftop solar potential of over 100,000 MWh/yr. Of all the buildings with solar power potential, 19% could supply 85% of the total potential energy. These methods have the capacity to be applied to the entire county and to other regions seeking to efficiently utilize solar energy.