Hyundai and Kia are the latest automakers to announce plans to offer solar panel roofs on their cars.
The Korean firms on Wednesday said solar roofs, some with a translucent design, will start being made available from 2019, without mentioning specific markets and vehicles.
Audi announced plans to offer solar roofs a year ago, and of course Karma (formerly Fisker) already offers them on its Revero sedan.
Hyundai and Kia said the solar roofs will be used to charge vehicle batteries and will initially be fitted to hybrids and even cars with conventional powertrains. In the latter, the generated power can be used to power ancillaries like the air conditioner or seat heaters, thus saving that little bit of extra energy to improve the overall efficiency.
There are currently three systems in development. The first is a conventional silicon-based solar roof that will be fitted to hybrids and said to be capable of charging the battery between 30 and 60 percent of capacity within a day, depending on the level of sunlight.
A more advanced design with a translucent appearance will follow and initially be used on cars with conventional powertrains. The semi-transparent solar panels are applied to a panoramic sunroof, allowing the roof to generate energy while still letting light into the cabin. And eventually Hyundai and Kia will introduce lightweight solar panels that can be used for the hood or trunk lid of a car.