Stanford Solar Car shows potential of sun for automotive

04 Oct 2019

Alta Devices solar tech expected to power Stanford’s car 3000km in trans-Australia rally.

This year's model: the Alta Devices PV-powered Stanford Solar Car.

This year, for the first time in BWSC history, a solar car will use flexible, glass-free solar panels that not only deliver high levels of power, they can also be manufactured at cost-effective prices. Alta Devices comments that “not only is this a big step for the team, the race, and the company, but it will provide a vision of what solar technology might look like for mass-market automotive.”

Jian Ding, Alta Devices CEO, said, “For solar to be realistic for the broad auto market, it must have several important characteristics: It needs to be flexible enough to conform to the surfaces of innovative vehicle designs, maintain high efficiency even in the hottest weather conditions, and be manufacturable at scale.”

Silicon limits

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 typically brittle, which makes it difficult to handle and integrate into curved automotive surfaces. 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. 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.

Alta Devices thin-film gallium arsenide solar technology 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. It can also be produced at mass-market scale.

Stanford Solar Car Project

The Bridgestone World Solar Challenge is the world’s best-known solar-powered car race. The road race is over 30 years old, held every two years in the Australian outback, and covers a challenging route more than 3000 km (1864 miles) long from Darwin to Adelaide. Over 50 teams, composed of students from high schools and colleges, 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 SSCP 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 in.

This 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. Ding added, “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.”