In some parts of the globe, solar energy is available throughout the year. In areas where the terrain is mostly flat, it is justifiable to use solar power in the automotive industry. Previous publication explored the concept of a solar-battery car with single and double solar array-trailers. Solar array-trailers maximize the acquired solar energy thereby minimizing the use of battery power. The resulting excess power derived from solar-trailers can be used to drive the car and accessories that are necessary in some parts of the world. Building on previously published results, this paper aims to determine the applicable limits of the car-trailer concept. Variations to the reference configuration are considered, and the corresponding battery power needed is calculated. Upper limits to the drag area coefficient, ground inclination, and rolling resistance are established. Furthermore, an effective rolling resistance factor for the trailer is determined since manufacturing imperfections, component flexibilities and the misalignments of trailers limit the applicability of the car-trailer system. The use of trailers is not justifiable for an effective rolling resistance factor less than one. An ideal environment for the application of solar-battery cars, on a global scale, may be the drive across the Australian continent along the Stuart Highway/Highway1. Such a drive is used by the World Solar Challenge to assess the performance of various categories of solar cars. A similar track is used in this publication to assess the response of solar-battery cars with solar-trailers. Cumulative as well as daily energies required for such a drive are reported for a car, and a car with trailers. Furthermore, the response under clear/cloudy conditions, throughout the year, is discussed. The results are compared with energies required by a typical 'race' car. The paper concludes with a summary of the results. (C) 2017 Elsevier Ltd. All rights reserved.