Effect of angular losses on the output performance of solar array on long-endurance stratospheric airship

The solar array is one of the major components of long-endurance stratospheric airship which converts the solar energy to electric energy. Exact calculation of the output performance of solar array is significant to the operation of the airship. The move of the sun and the curve surface of the airship lead to the dramatic change of the incidence angle of solar radiation. Therefore, the angular losses, caused by the change of incidence angle, decreasing the efficiency of solar cell and then reducing the output energy of solar array, should be taken into account. But the relevant investigations are rare. In this paper, a simplified numerical model including solar radiation model, thermal model and angular losses model was established. A MATLAB computer program was developed based on the model to research the deviation of output energy of solar array with/without angular losses. The effects of date, airship's attitude and latitude on the deviation were also discussed in detail. The result indicates that the output energy of solar array on stratospheric airship was overestimated without considering the angular losses and the angular losses should be taken into account for an accurate calculation. It is believed that the present models and program will lead to a better design for the energy management system of stratospheric airship.