Recently, according to increase of the interest in the field of unmanned aerial vehicle(UAV), the various purpose of UAV has been developed. To complete a mission successfully, the long-endurance of UAV has become a key challenge. A solar-powered UAV, which is equipped with photovoltaic cells on top of its wings and its energy sources are solar power and rechargeable batteries, has received considerable attention in this fields. As the battery capacity of the UAV is limited, environmental conditions such as solar radiation and wind are considered for endurance ability. Therefore, it is necessary to make an optimal flight path which efficiently manage the energy of a solar-powered UAV considering the meteorological environmental conditions.In this study, the primary goal is to develop an optimal path planning for a solar powered UAV. Also, the energy flow models including the solar radiation model, energy consumption model, and battery model are represented. Moreover, the solar radiation model is compared with the observed data at Jeonju observatory. In addition, to consider the meteorological condition, the numerical weather data is provided by Korea Meteorological Administration. In order to validate the model respectively, the virtual flight system was constructed and the experimental approach was carried out. To find an optimal path under the limited environmental constraints, we examine the problem of optimal path planning using the direct collocation method. The objective function is to maximize the remaining energy stored in the battery while satisfying the boundary conditions and feasibility constraints on the states of the UAV. Some simulation cases are presented to demonstrate the feasibility of optimal control. Finally, The results of the optimal path planning show that the optimal path can reduce the power consumption and maximize the remaining energy amount by using the meteorological condition.