Fraunhofer ISE Introduces Invisible Solar Roofs For Vehicles

September 2nd, 2019 by Steve Hanley

As the EV revolution progresses, it makes perfect sense to integrate solar cells into the exterior of cars, particularly on horizontal surfaces like roofs that are perfectly positioned to soak up sunshine and turn it into electrons. Toyota and Hyundai are already offering solar roofs on some cars. Sono Motors takes the idea even further with its new Sion, embedding solar cells in the hood and the doors of the car.

The Sion will be available only in black, partly because many of the people who pre-ordered the car prefer that color and partly because it helps mute the visual impact of the solar cells. Now Fraunhofer ISE says it has invented a new way to manufacture a solar roof for vehicles that can be any color the manufacturer wants. The coloration process reduces efficiency by about 7%, but if it helps the solar car roof idea become more popular, the trade-off is worth it.

One secret of the new Fraunhofer ISE solar roof is a shingle-like arrangement of the solar cells, which overlap each other just like shingles on a normal roof. They are held in place by a special adhesive that doubles as an electrical conductor, eliminating the wires that normally connect solar cells together.

Another secret is a special colored coating inspired by the morpho butterfly, which makes the solar cells nearly invisible. “The color possibilities are almost endless,” says Dr. Martin Heinrich, head of PV for Mobility at Fraunhofer ISE.

The new product has a power output of about 210 watts per square meter. After testing the new solar roof over the past year in North America and Europe, Fraunhofer says it can add about 10% to the range of a typical electric car.

“In order to realize a CO2-free energy supply in all sectors, we have to promote the expansion of photovoltaics vigorously, even beyond house roofs and open spaces. In the future, solar modules will be integrated into our already built environment even more, for example into vehicles,” explains Dr. Andreas Bett, Institute Director of Fraunhofer ISE.

Adding 5 miles of range to an electric car every day may seem like a small thing to get excited about, but the researchers at Fraunhofer have been applying their discovery to other areas of the transportation sector as well. Many CleanTechnica readers have commented that the roof of a typical car is quite small, but the roof of a semi-trailer would be an ideal location for solar panels.

Over the past several years, Fraunhofer ISE has conducted experiments on large trucks and found that each truck so equipped has the potential to generate between 5000 and 7000 kilowatt-hours of electricity over the course of a year. That’s enough to allow up to power a truck for up to 7,000 kilometers. Tell a roomful of commercial fleet managers they could power each one of their vehicles that far for free and watch their eyes light up!

Electric trucks are on the cusp of going mainstream. Equipping them with solar panels makes so much sense, it would be almost negligent not to do so.









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