Solar Charging On a Budget with Ford C-MAX Solar Energi
Using solar energy to charge an electric car is not a new idea. A lot of plug-in vehicle drivers have been doing it for several years. It's a smart energy strategy, but the initial investment was substantial, so that leaves plenty of room for a better solution.
Ford's idea is to do without a large rack of solar panels which people fit on their roof or in their garden. The only solar panels used here are on the car's roof, and they're installed by Ford itself. That sounds good because car companies are good when it comes to bringing costs down, and making new expensive technologies affordable.
Ford is using its C-MAX Energi plug-in hybrid as a conceptual starting point. The only problem is that there's only 1.5 square meter of solar cells on the car's roof. That's definitely not enough to power a car. Other car manufacturers have already considered at the subject—most notably, Toyota for its Prius, and all German carmakers for their most expensive sedans. They offer the option of a solar panel built into the roof, but it's only for cooling the car when parked under the sun.
One-and-a-half square meters of solar cells is a nice benefit that every EV would enjoy. (Ford should offer the option right now). But leaving the car parked a whole day in a sunny place would probably only bring enough energy to drive an extra four or five miles. Still good, but more is needed. So Ford developed a 5.3 by 4.3 meter canopy fitted with a Fresnel lens on its top, to direct sunlight to the solar cells of the car parked below. It's basically a giant magnifying glass.
The good part is that this can be cheap. Fresnel lenses are not expensive, and the only question is how effective they can be. Concentrating solar power works great on thermal systems (check Planta Solar 10 in Spain), but concentrated photovoltaics is still fairly new, and much less documented. Ford said its system will boost the impact of the sunlight by a factor of eight. That's impressive and critically it's enough to fully charge the C-MAX Energi in a day. The 7.6 kWh battery is good for 21 miles of zero emission driving, all courtesy of the sun.
Increased wear on the cells may be an issue, and so is heat. We should note that Ford could have fitted the solar cells into the roof, but it didn't. They're raised slightly above the roof. This is still a concept, it remains to be fully field-tested. That's coming.
This C-MAX Solar Energi Concept will be on display at the 2014 International Consumer Electronics Show in Las Vegas, before it's sent back to Georgia Institute of Technology, which collaborated with Ford to develop this concept. Photovoltaic cells are from SunPower, and many months of testing are needed to find out how effective the system is as a daily charging appliance, but the idea is clearly exciting. It may also have potential in developing countries where people can't afford large photovoltaic systems, and the need to shift to cleaner cars is urgent.
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