Flexible organic solar cells (FOSCs) are one of the most promising power sources for aerospace aircraft due to their attractive advantages with high power-per-weight ratio and excellent mechanical flexibility. Understanding the performance and stability of high-performance FOSCs is essential for the further development of FOSCs for aerospace applications. In this paper, after systematic investigations on the performance of the state-of-the-art high-performance solar cells under thermal cycle and intensive UV irradiation conditions, in situ performance and stability tests of the solar cells at 35 km stratospheric environment were carried out through a high-altitude balloon uploading. The encapsulated FOSCs with an area of 0.64 cm² gave the highest power density of 15.26 mW/cm² and an efficiency over 11% in the stratospheric environment, corresponding to a power-per-weight ratio of over 3.32 kW/kg. More importantly, the cells showed stable power output during the 3-hour continuous flight at 35 km and only 10% performance decay after return to the lab, suggesting promising stability of the FOSCs in the stratospheric environment.

Current stratospheric airships generally employ photovoltaic cycle energy systems. Accurately calculating their power generation is significant for airships’ overall design and mission planning. However, the power generation of solar arrays on stratospheric airships is challenging to model and calculate due to the dynamic nature of the airships’ flight, resulting in continuously changing radiation conditions on the curved surface of the airships. The power generated by the airship solar array was modeled herein through a combination of the flight attitude, spatial position, time, and other influencing factors. Additionally, the model was modified by considering the variation in photovoltaic conversion efficiency based on the radiation incidence angle, as well as the state of charge and power consumption of the energy storage battery pack. This study compared the measurement data of power generation in real flight tests with the calculation results of the model. The comparison showed that the results of the calculated model were highly consistent with the actual measured data. An average normalized root-mean-square error of 2.47% validated the accuracy of the newly built model. The generalizability and rapidity of the model were also tested, and the results showed that the model performed well in both metrics.

High-energy-density lithium batteries play a crucial role in the lightweight design of stratospheric airship systems. This paper conducts an in-depth experimental study of the equivalent circuit model of soft-pack batteries, with a focus on how parameter identification methods affect model accuracy. To this end, first-order RC, second-order RC, and third-order RC equivalent circuit models were constructed, and model parameters under different temperature and current conditions were obtained through constant-current intermittent discharge experiments. During the parameter identification process, special consideration was given to the impact of sampling time on voltage measurements and the interdependent constraints among models. Additionally, the effects of current, temperature, and SOC (state of charge) variations on ohmic resistance and polarization resistance–capacitor parameters were analyzed. The experimental results show that the root mean square error (RMSE) of battery terminal voltage calculated using parameter identification methods that account for these factors is significantly lower than when these factors are not considered. By comparing the voltage calculation accuracy and operational efficiency of the three models, the second-order RC model was determined to be the preferred choice due to its simple structure, high computational efficiency, and superior accuracy.