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Audi partners with Alta Devices on thin-film solar cells in panoramic glass roofs; first prototype this year

Audi and Alta Devices, a wholly-owned US subsidiary of the Chinese solar-cell specialist Hanergy, have signed a Memorandum of Understanding on Strategic Cooperation in thin film solar cell technology. Through this cooperation, the partners aim to generate solar energy to increase the range of electric vehicles. The first prototype is to be built by the end of 2017.

As the first step in the joint Audi/Hanergy thin film solar cell research and development project, the partners will integrate Alta Devices’ GaAs thin-film solar cells into a panoramic glass roof. The system will extend EV range by feeding solar energy into the internal vehicle electrical system—supporting air conditioning and other electrical appliances.

In the long term, by leveraging the technologies from both sides, the two parties plan to gradually transition to utilize thin film solar technology to feed solar energy into the drivetrain battery to provide additional primary power for vehicles.


The project will not only contribute to Audi’s vision of emission-free mobility, but also advance the application of thin-film solar technology for global primary energy generation. The two sides plan to jointly present an Audi vehicle prototype featuring an integrated prototype solar roof solution by the end of 2017.

The range of electric cars plays a decisive role for our customers. Together with Hanergy, we plan to install innovative solar technology in our electric cars that will extend their range and is also sustainable.

—Audi Board of Management Member for Procurement Dr. Bernd Martens

Alta Devices produces the thinnest, lightest, and most flexible solar technology on the market: 110 µm thick, less than 200 mg, and capable of bending around a 40 mm cylinder. This form factor makes for easy integration into curved glass automotive roofs, and provides the most power possible in every type of lighting.

This partnership with Audi is Alta Devices’ first cooperation with a high-end auto brand. By combining Alta’s continuing breakthroughs in solar technology and Audi’s drive toward a sustainable mobility of the future, we will shape the solar car of the future.

—Dr. Ding Jian, senior Vice President of Hanergy Thin Film Power Group Limited, CEO of Alta Devices, Inc. and co-leader of the Audi/Hanergy Thin Film Solar Cell Research and Development Project

Alta Devices grows a thin layer of GaAs on top of a single crystal GaAs wafer using a high throughput metalorganic chemical vapor deposition (MOCVD) process. It then removes this thin layer via an epitaxial lift-off (ELO) process which leaves a thin, flexible, and lightweight solar cell. Alta Devices started manufacturing and selling its third generation (Gen3) product in 2015. In 2017, it began rolling out the fourth generation (Gen4) product line.

Alta Devices’ technology holds single and dual junction solar efficiency records at 28.8% and 31.6% respectively. It achieves its record-breaking efficiencies through the observed phenomenon called “Photon Recycling”. In this process photons bounce off the back of the solar cell which allows them to be recaptured by the material and converted to electricity. Thus, more energy is captured where it would have been lost using traditional solar technology.

Gen4 represents a 30% reduction in mass resulting in an areal density of 170 g/m2 unencapsulated.



You might get 300 W from a car roof, which if left in the sun for 7 hours might yield 2.1 Kw H which would give you about 6.5 miles driving.
This would be handy for a PHEV if you couldn't plug it in at work.


The article is somewhat light on factual information but I doubt that you could get more than a KwHr even in a sunny location. The problem is that the roof does not directly face the sun. Maybe you could design special parking spots with a built in tracking mechanism:)


The best solution would be chargers at work and in mall car parks. Even low power ones of say 1-3 Kw would be a big help for a PHEV (or any BEV).
Ideally these would be "smart" chargers which would knock off when demand on the grid was heavy.


When mass produced at lower cost in automated factories, these 31+% units will make excellent future fixed solar farms?


I think a better use of this technology or a similar technology would be to generate solar power from office building windows. Lots of area and you need the glass anyway

Thomas Pedersen

I have always claimed this option would be economical, despite possible low utility ratio, because installation and power management costs drop to near zero when installed in a factory into a car that already has those components.

I imagine the cost to the factory is counted in tens of dollars, if that when fully implemented.


@Thomas, it should be cheap if factory fitted, but don't expect too much from it.
@Harvey, the 31% might be very expensive as it is a dual junction device, but you never know.


Make cells with 20% perforations and use them as window tinting.


It might make enough power to run a fan cooling the interior.

Luna Eva

Audi and Alta devices have signed a MOU to develop automobiles with integrated high-efficiency solar cells. Through this MOU, the partners aim to generate solar energy to increase range of Audi electric vehicles. The first joint prototype to be built by the end of 2017. As the first step of the project Audi & Alta devices will integrate solar cells into panoramic glass roof. In future, almost entire roof is to be covered with solar cells. The electricity produced from these cells will flow into the car's electric system and supply electricity for the car's air conditioner,seat-heater etc. This project will be helpful to achieve emission-free mobility. Along with these things we shouldn't ignore its repair and maintenance. If we want to get high return from our Audi, then its better to take proper care of it. From my point of view, it's better to follow the maintenance guidelines mentioned in the owner's manual and get the vehicle serviced from a professional Audi repair shop. These branded cars need care by trained technicians and we can get trained technicians in a professional repair shop. If anybody searching for a professional Audi repair shop near Dania Beach, Motronix is the best choice.

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