Solar energy is powering so much of our daily lives, so why can’t it help power your car too? Before you get your hopes up, this is not a solar powered car similar to what engineers the world over compete each year in the World Solar Challenge with vehicles powered exclusively by the sun. This is a breakthrough nonetheless. Ford, SunPower, and Georgia Tech have partnered together to put high efficiency solar cells on the roof of a plug-in hybrid allowing owners the potential of never charging the car using the electrical grid.
Researchers developed an off-vehicle solar concentrator that uses a special Fresnel lens to direct sunlight to the solar cells while boosting the impact of the sunlight by a factor of eight, much like a magnifying glass. The patent-pending system tracks the sun as it moves from east to west, drawing enough power from the sun through the concentrator each day to equal a four-hour battery charge (8 kilowatts).
By using this system, Ford estimates the C-MAX Solar Energi Concept will reduce the annual greenhouse gas emissions a typical owner would produce by four metric tons, the equivalent of what a U.S. house produces in four months.
Walter Wang is an energy tax policy expert and managing editor of CleanTechies. A list of his publications can be found here. Follow Walter on Twitter: @energytaxprof
3 comments
Solar is best on a fixed location at the correct angles, IE Facing South, no shade.
The concentrator won’t help if you not parked under it.
So Install Solar at your home and use it wisely. Get a 100% Electric car or at least a plugin since electric is about $1 vs a gallon of gas to go the same distance.
So many bad / partially-bakedideas in one place.
What about seasonal sun path motion?
How hot would it be inside that car at the end of the day? The good news is that I could have solar cooked roast beef for dinner.
If I need the car during the day, how do I get to it? I’m not walking into a solar oven.
Plexiglass Fresnels have a limited lifetime and are not going to be happy with snow or other debris. You’ll need a robust support system for them, given the span required (see comment above about seasonal sun path motion).
Jim’s right, just install a conventional solar panel array and charge from the grid. Much simpler and more robust.
— Roger
Jim and Roger have valid points, though the concentrating concept here is intriguing. It’s difficult handling concentrating flux density with silicon-based cells, but it looks like some thought has gone into it with larger traces and metal backing for the cells. The car roof and body can shunt some of the heat buildup. If I had one of these hybrids in my driveway, I would ad a spray wash to douse and cool the car before entering.
The real tricky part here is the tracking–how to keep the flux density even on the cells. Non-imaging fresnels must have been used rather than typical ones that magnify to a point. The seasonal variation in solar angle could be accommodated by aligning the car under the canopy along a specially-marked grid on the ground.
The acrylic fresnels won’t yellow like other plastics, but they would be prone to cracking in cold weather. Even so, that shouldn’t be a deal-breaker. At 8x concentration, a few cracks probably wouldn’t hurt, and acrylic is cheap stuff that can be replaced periodically.
The biggest issue with the design is that driving the car would be coincident with the ideal charging time, i.e. daytime. Maybe the canopy could be put to some other use when the car is not under it. Roger suggests a good idea to use it as a cooker. Or, use a second roll-around PV array.
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