The latest company looking to power future EVs with sunlight is China's Hanergy Holding Group. Joining the likes of EVX Ventures (the folks behind the distinctive Immortus), Hanergy unveiled a quartet of thin-film solar cell-equipped vehicles in Beijing over the weekend, each of which is designed to commute around and beyond the city without the need to plug in.

Having purchased California-based Alta Devices several years ago, Hanergy is working to expand gallium arsenide (GaAs) solar cell technology, which claims record-breaking conversion rates as high as 31.6 percent. The cells' lightweight, flexible nature makes them well-suited for integration into a vehicle's structure, and Hanergy's concept cars feature between 38 and 81 sq ft (3.5 and 7.5 sq m) of cells. Hanergy estimates that the cells can deliver about 50 miles (80 km) of driving per day from five to six hours of sunlight, no external charging involved.

Many a trip runs farther than 50 miles, and weather conditions have a habit of changing, so Hanergy has also incorporated an external charging port for the lithium batteries. The company claims the vehicles can drive for up to 217 miles (350 km) per charge, but it doesn't detail the size of the battery or layout of its electric powertrain(s).

An intelligent control system and accompanying app help the driver to manage charging, travel and weather modes. Ultrasonic cleaning technology keeps the panels clear of dirt and debris to ensure smooth energy collection. The four cars are designed in different styles, including an almost shooting brake-like sports car and a city hatchback.

Hanergy says that it performed the R&D for the four vehicles independently and that the cars can be commercialized. Vehicle integration of thin-film cells is part of Hanergy's greater mobile energy strategy, which also calls for using the cells in unmanned aerial vehicles, mobile electronics, backpacks and clothing.

Sources: Hanergy, Bloomberg