Tdworld 20095 Stanford Solar Car 2019

Solar Car Shows Potential of Flexible, High-Efficiency Solar for Automotive

Oct. 17, 2019
The Stanford Solar Car is using flexible, glass-free solar that delivers high levels of power, can be manufactured at cost-effective prices.

The Stanford Solar Car, competing in October’s Bridgestone World Solar Challenge (BWSC) race, has been powered by Alta Devices solar technology.

This year, for the first time in BWSC history, a solar car is using flexible, glass-free solar that also delivers high levels of power and can be manufactured at cost-effective prices. Not only is this a big step for the team, the race, and Alta Devices, but it offers a vision of what solar technology might look like for mass-market automotive.

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.

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. 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.

"For solar to be realistic for the broad auto market, it needs to have several important characteristics," said Jian Ding, Alta Devices CEO. "It must 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."

Alta Devices thin-film gallium arsenide (GaAs) 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.

The BWSC is a solar-powered car race, held every two years in the Australian outback. It covers a challenging route more than 3000-km (1864 miles) long from Darwin to Adelaide. 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.

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