When the Stanford Solar Car competes in this month’s Bridgestone World Solar Challenge (BWSC) race, the car will be powered by flexible, glass-free solar from Alta Devices solar technology.
Not only is this a big step for the team, the race, and Alta Devices, but it provides a vision of what solar technology might look like for mass-market automotive, said Alta Devices in a press release.
BWSC is a road race that is over 30 years old. It is held every two years in the Australian outback and covers a challenging route more than 3000 kilometers (1864 miles) from Darwin to Adelaide. Over 50 teams, composed of students from high schools and colleges, will compete in pushing the limits of technological innovation.
The race rules mandate that the cars must be designed, built, and raced by the teams, and run primarily on solar power, with very limited use of stored energy.
The 2019 Stanford solar car, called “Black Mamba” has a new sleek design versus previous team cars and the Stanford team built a custom oven to cure the large shell composites. The car is the 14th solar car that the Stanford team has designed. This year’s design is asymmetrical with a single aerodynamic shell covering the body. Alta Devices solar cells have been integrated onto the top surface of the vehicle.
Due to the ability of the solar to flex, the curves of the vehicle design were preserved. Jian Ding explains, “In the future, mass-market electric vehicles will be designed for long-range, as well as safety, and sustainability. They will use extremely light-weight and aerodynamic materials. Solar will be incorporated to seamlessly cover the body of the car, maximize range, and power auxiliary systems. Whenever there is sunlight, the car will always be charging.”
To date, solar technology used on solar race cars, luxury cars, or concept vehicles has typically been silicon solar or specialized solar developed for space applications. Silicon solar, while low-cost, is very brittle, which makes it difficult to handle and integrate into curved automotive surfaces, according to Alta Devices. Silicon has relatively low energy conversion efficiency compared with other materials, making it harder to generate the desired amount of power from the limited area of a car roof. Moreover, silicon solar quickly becomes warm during operation and loses efficiency as temperatures rise. Overall, this results in less vehicle range or available power per day, the company said.
Space solar cells are high efficiency, but like silicon, very brittle and don’t manage heat well. In addition, the traditional complex and time-consuming manufacturing process makes them very expensive, according to Alta Devices.
Alta Devices uses thin-film gallium arsenide solar technology, which is a newer technology relative to silicon and space solar. It is flexible, lightweight, high-efficiency, and has structural properties that allow it to run much cooler, said the company, adding that it can also be produced at mass-market scale.