Exploring the characteristics of power density of tracking PV modules for high-altitude stationary solar-powered airplanes

The characteristics of power density of PV (photovoltaic) modules play a key part in the flight performance of solar-powered airplanes. Firstly, this paper establishes a model of power density for PV modules, taking into consideration the temperature of PV modules, flight altitude, flight latitude, and year-round seasons. Based on this model, this poper analyzes the variation of the day-average power density of PV modules for horizontal surfaces and surfaces perpendicular to the Sun. this paper presents a comparative study of the characteristics of power density of tracking PV modules (TPM) under three types of tracking methods, and the results show that tracking PV modules improve the power performance during both the daylight in one day and during a whole year. Then, based on two typical solar-powered airplanes, "Helios" and "Zephyr", this paper proposes a new concept of solar-powered airplane with tracking PV modules and analyzes their effects on improving the average net power density. The results show that the tracking PV modules can increase power density by 32% to 66%, and at times even up to 116% if well designed. From the point of view of both energy and aerodynamic efficiency, this paper shows that it is necessary to apply the tracking PV modules to designing stationary high-altitude solar-powered airplanes due to their superiorities.