At this years Consumer Electronics Show, held next in Las Vegas, Ford Motors has announced it will show off a solar powered Ford C-MAX Energi. The concept car is also a research platform that shows a way to get around the primary limitation of solar powered cars: The lack of surface area on a car for enough solar panels to power the car. The C-MAX Solar Energi is the first demonstration of a practical solar powered electric car.
However, there is a footnote to that claim - Recharging the C-MAX Solar Energi on solar power at a reasonable rate requires a special canopy that concentrates solar power.
What Ford has done is add solar panels, provided by SunPower, to the roof of a normal C-MAX Energi. These solar panels are used to recharge the car, meaning you can drive purely on sunshine and remove all possibility of any fossil fuel generated electricity. Isn't infinite driving range with no side effects what we all want? Yes, but, this vehicle doesn't quite deliver on that promise.
The C-MAX Energi is similar in size to the Toyota Prius V, but is a plug-in hybrid offering 20ish miles of electric range. That gives the C-MAX Energi an EPA-estimated 108 MPGe city and 92 MPGe highway, for a combined 100 MPGe. Recharge time at a regular charging station is about 2 hours. The video embedded in this report is a good review of the stock standard C-MAX Energi.
The C-MAX Solar Energi adds solar panels to its recharging capability. The roof has about 1.5 square meters of solar panels, and by itself those panels generate about 300 watts in optimal conditions. Given that the C-MAX Energi has a 7 kilowatt-hour battery pack, recharging solely off the solar panels would require several days. That's because the surface area of a car isn't sufficient for powering a car. At 300 watts, charging 7 kilowatt-hours requires over 23 hours of daylight, and at about 6 hours of light per day, means a 4 day recharge time.
How, then, is this the first practical solar electric car? That's where the special canopy comes into play. The canopy is a "solar concentrator" utilizing a fresnel lens to magnify the power delivered to the solar panels by about 8 times. That's enough to cut recharging time to about 4 hours solely on solar power. Watch the C-MAX Solar Energi video on YouTube. While recharging underneath the solar canopy, the C-MAX Solar Energi moves itself from side to side to optimize solar power efficiency.
A four hour recharge, on solar power, is much better than a several day recharge on solar power. But it requires the solar concentrator canopy, which would limit your choice parking locations. Most think it's better to put solar panels on fixed infrastructure so more solar capacity can be installed. Solar carports for parking lots are becoming popular, and can more easily assure optimum solar efficiency than you can with car-mounted solar panels.