Ford has announced a new concept car which will make its debut this month. The Ford C-Max Solar Energi Concept has a solar panel system on the roof which tracks the position of the sun. This, the designers say, means it can produce power the equivalent of a four-hour battery charge which would allow the car to travel 21 miles powered just on electricity.

The concept car will be on display at Consumer Electronics show in Las Vegas before testing begins to see if production is feasible. The solar panel roof uses a separate solar concentrator lens, similar to a magnifying glass, to absorb more energy. Ford claim that a day's worth of sunlight will produce the same performance from the Solar Energi Concept as is given by their conventional plug-in hybrid car. 

Ford says that by using the solar power system, drivers will not be dependent on the grid to use the car. The use of solar power is also said to be particularly helpful in powering ancillary systems such as air-conditioning.