Ford’s new solar-powered hybrid car can charge up without plugging in

Ford has designed a new concept car that it’s planning to show off at CES 2014 next week, which isn’t very surprising — car companies make new concept vehicles all the time. However, this time Ford is looking to harness all that free energy the sun is raining down on us every day in a plug-in hybrid. The Ford C-Max Solar Energi has 1.5 square meters of solar panels on the roof that can juice up the battery while it’s parked outside. It’s not as simple as bolting some photovoltaic solar cells to the roof of the car, though.

Like other plug-in hybrids, the C-Max Solar Energi has both gas and electric motors. Its total range is impressive at 621 miles, which includes 21 miles of all-electric driving. Another thing it has in common with plug-in hybrids is the “plug-in” part. If the sun is unavailable, you can attach the C-Max Solar Energi to the grid like other electric vehicles. The new concepts and ideas come into play when you’ve got a clear view of the sky.

The solar panels on the roof of the Solar Energi were designed and manufactured by California-based SunPower. These solar cells are a bit different than the cells produced elsewhere. There is a single metal layer on the back of the cell that supports the silicon photovoltaics. It’s a flexible design, which is utilized in the curved glass housing on the top of the car. SunPower also claims its cells can harvest 50% more energy over the same surface area than conventional cells.

For all the supposed efficiencies of these solar cells, 1.5 square meters just isn’t enough surface area to power a car. That’s why all the solar powered cars you see are tiny light-weight things that coast slowly over long distances. The C-Max Solar Energi makes use of a special Fresnel lens canopy positioned above the car to boost solar exposure several times over.

A Fresnel lens is a type of compact lens originally developed for use in lighthouses that acts as a magnifying glass. If you’re picturing a canopy of breakable glass ready to rain down on your car, think again. Frensel lenses are usually made from plastics like acrylic, so they are light and durable while also being cheap to make. When parked under the Fresnel lens canopy, the C-Max Solar Energi will track the sun and roll slowly backward or forward to keep the most intense area of solar energy concentrated on the panels.

Ford says that using this system the car can gain the equivalent of a four-hour plug-in charge (about 8 kilowatts) over the course of the day. For many people, that’s enough to commute or run some errands without using gas or plugging into the grid. Without the overhead canopy of lenses, the C-Max pulls in too little power to justify putting solar panels on the car in the first place.

What Ford is proposing here is a combination of vehicle technology and infrastructure, which isn’t really much different than the regular plug-in hybrid scenario. We’re already seeing the expansion of supercharging stations for electric vehicles, and a Fresnel lens canopy is a lot cheaper. The Ford C-Max Solar Energi will be tested in the real world after CES to see if the technology is feasible to bring to market.