Audi has announced a joint development project with Alta Devices, a subsidiary of Chinese solar-cell specialist, Hanergy, on a solar roof.

Audi e-tron quattro concept

Audi e-tron quattro concept

The first step will be to integrate the thin-film solar cells into panoramic glass roofs, and then to present the prototype by the end of this year.

It's expected that the solar cells will eventually cover nearly the entire roof, providing additional electricity for EVs and hybrids - in respect mostly to seat heaters and air conditioning systems, but also to ultimately provide surplus energy to the HV systems for more range.

The efficiency of Alta Devices' thin-film, flexible solar cells is reported to be over 25%.