An unmanned aerial vehicle (UAV) solar irradiation assessment system may automate several design parameters of solar panel design, cost and payoff estimations, and installation. The system determines the irradiance at various locations on a roof during various time periods. The system accounts for the effects of various existing, potential, or future obstacles proximate the structure. In some embodiments, a visual model of the roof may be shown with a heatmap of irradiance values and/or graphical placement of solar panels. In other embodiments, the data may be analyzed and reported without visual presentation.