Recently, the demand of UAVs(Unmanned Aerial Vehicle) have been increased and UAVs are becoming popular, because avionics are getting smaller and cheaper. And, techniques of flight control have been improved as a result, UAVs are being developed for various purposes of surveillance and reconnaissance. Long endurance flight of UAVs are very important to conduct these purposes. When the flight time has been increased, also the time of reconnaissance and surveillance are increased. There are various methods of long endurance flight of UAVs, and a solar UAV is a powerful candidate for long endurance flight. A solar UAV gets their energy from the sun during the day and uses the energy during the flight. And, the surplus energy is stored in battery and then, the energy of battery is used for night flight. If the principle of a solar UAV is ideally performed, a solar UAV is capable of flight during weeks or months. If a solar UAV has long endurance capability, it may perform the task, such as a communication relay and artificial satellite partly. So that, it is important to obtain a maximum energy from the sun. Also, it is indispensible to manage power of solar UAV efficiently. This study has been conducted to evaluate the possibility of long endurance flight of a solar UAV with ground testbed. Also, computer simulation has been conducted in order to validate the theoretical model of energy and flight power. This ground testbed is used for virtual flight experiment. The aircraft on the testbed demonstrates the attitude of solar UAV due to flight by 3-axis motion, and monitor power management. Also, a performance of main modules, such as solar module, MPPT, and battery module of solar UAV were evaluated using the ground testbed.