New Solar Cell Could Upgrade Auto Glass

A 4-year project to create solar-powered windows for automotive and other potential applications is seeing a light at the end of the tunnel.

As part of his just-completed doctoral studies at Flinders University’s School of Chemical and Physical Sciences in Adelaide, Australia, Mark Bissett has developed a solar cell using carbon nanotubes.

The new, low-cost carbon nanotubes are transparent, meaning they can be “sprayed” onto windows without blocking light. They also are flexible so they can be weaved into a range of materials including fabric, a concept already being explored by advertising companies.

“This technology could definitely have applications in replacing automotive windows,” Bissett tells WardsAuto in an email. “This could be especially applicable for vehicles such as buses or coaches with large numbers of large windows.”

Bissett says the solar windows have a tinting effect on the glass. The system also could reduce sunlight entering a vehicle as well as supply it with electrical energy.

“I doubt that, with the efficiencies currently possible with these devices, the use of solar windows could power the engine of an electric car,” he says, “but it certainly could supplement a car’s electrical power needs, powering auxiliary devices such as navigation systems or audiovisual equipment within the vehicle.

However, “this technology is still in its infancy and will still require further research and optimization before seeing commercial availability.”

Carbon nanotubes are both more efficient and less expensive to make than traditional silicon-based solar cells, Bissett contends.

“Solar power is actually the most-expensive type of renewable energy – in fact, the silicon solar cells we see on peoples’ roofs are very expensive to produce, and they also use a lot of electricity to purify.”

The overall efficiency of silicon solar cells is about 10%. Even when they’re functioning at optimal efficiency, it could take eight to 15 years to recover the energy it took to manufacture them, because they’re produced using fossil fuels.

While the amount of power generated by solar windows would not be enough to completely offset the energy consumption where they are used, Bissett says they still have financial and environmental advantages.

“It’s basically like tinting the windows, except they’re able to produce electricity.”

Bissett says the technology mimics photosynthesis, the process used by plants to obtain energy from the sun.

“A solar cell is created by taking two sheets of electrically conductive glass and sandwiching a layer of functionalized single-walled carbon nanotubes between the glass sheets,” he says.

“When light shines on the cell, electrons are generated within the carbon nanotubes and these can be used to power electrical devices.”

Only small prototypes have been developed in the lab thus far. Bissett says the next step will be to test the carbon cells on an “industrial stage.” If all goes according to plan, the material could be on the market within 10 years.

“When we first started the research, we had no idea if it would work, because we were the first in the world to try it,” he says. “So it’s pretty exciting that we’ve proved the concept.”