The design of a long endurance electric UAV is presented. The mission requirements are derived from civilian surveillance applications, such as forest, coast or border patrol. As such, long endurance is desired, which is tackled by a careful lightweight airframe design and an electric propulsion system assisted with solar cell arrays. The main steps of the design are covered, including numerical simulations, as well as construction, component and systems testing and flight testing. The feasibility of a green, low cost, small footprint UAV is demonstrated.