Solar-powered UAVs possess a unique capability to maintain continuous flight for hours, days, weeks, or even months. This research aims to develop a solar-powered UAV that can fly at low altitudes with extended endurance to establish a new record for full-day continuous flight in Taiwan. The UAV was designed with a 4.7-meter wingspan and a T-tail configuration to achieve this goal, utilizing materials and components available in the current market. The flight test was conducted on June 2, 2022, resulting in a remarkable 21 hours and 50 minutes of flight endurance, setting a record in Taiwan. While the full-day flight endurance target was not met, the UAV demonstrates the potential to achieve greater endurance with improvements in its construction and operational aspects.