Imagine (Again): A Car, Powered By Free Sunshine

Bertel Schmitt
by Bertel Schmitt
imagine again a car powered by free sunshine

EVs are, nice wouldn’t there be (putting range and price aside for a moment) one niggling problem: The power has to come from somewhere. And currently, the exhaust that will no longer be produced by the car, will come out of the smokestacks of a mostly coal fired power plant. Wouldn’t it be nice if we could power our cars from sunshine alone? Definitely renewable. And free. Honda is trying to do just that.

Sorry, forget about solar panels on roof and hood of the car. The power produced that way literally won’t get you far. But what about much larger solar panels on the roofs of your house or large parking garages? Now we are getting in the realm of the possible.

Honda said today that they will conduct a joint trial with Japan’s Saitama Prefecture to “examine the potential of low-carbon transportation systems driven by solar power,” as The Nikkei [sub] reports.

The study focuses mainly on train stations, where cars are parked during the day until the salaryman returns from the city. Large solar panels on the roofs of these stations could provide sufficient power to recharge the battery for the short ride home. Which also has the benefit of a clearly defined range.

“Joint use,” i.e. sharing of EVs, will also be studied.

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6 of 28 comments
  • MikePDX MikePDX on Dec 20, 2010

    Thanks, Bertel, this is a good topic, with lots of claims and reactions flying around. Let's run some numbers to get some Truth about solar charging of electric cars. Companies are already putting panels up on their roofs and parking areas, notably Google. (Neat construction video here: 250 Wh/mile is a good figure for a modern small EV. Let's assume commuting is 40 miles/day, 250 days/year. That's 10,000 miles/year = 2500 kWh/year. In Oregon this would require about 2500 watts of solar panels, 250 square feet of solar panels on a roof. ( A typical parking space is 10' by 20', about 200 sq. ft. So a parking space in Oregon that's exposed to the sun all day covered by solar panels would generate 80% of the energy to run a car used for commuting. I'm actually surprised it's that good. YMMV by location of course. As for cost, financed or leased over a period of years, solar panels are making good financial sense. Companies like SolarCity (, whose trucks are often in my Portland neighborhood, are putting up panels on homes and giving the homeowner lease rates that cut their electric bill. My roof needs replacing soon, then I'll do that myself. Of course the gotcha is the car isn't always parked under that panel, that's the point after all. If the parking space is at work, then it is parked under the panel most of the day five days out of seven. If the parking space is at home then most of the solar power comes in when the car's not there. In any case, the panels feed the grid during the day, offseting some other load like air conditioning, and the car can take charge back from the grid at night. Solar is only my third choice for powering electric cars. #1 is nuclear, which is quite safe and ready to scale up today. #2 is wind, which is coming up fast and has the advantage of offering its greatest output at night when most of our cars are charging. Solar pencils out as a fine power source too. That's the real point about electric cars, we can charge them from any source that comes along, starting with coal and and natural gas if necessary now, to break our addiction to foreign oil. Nuclear, wind and solar right away to get unhooked from carbon. When the next energy breakthrough like fusion comes along, our electric cars will be ready to use it.

    • Charly Charly on Dec 20, 2010

      Daytime power is a lot more expensive than nighttime power so the more economical method is to sell the solar power and buy nighttime power to recharge the batteries. ps. Nuclear isn't ready to scale. It takes atleast 6 years to build a nuclear powerplant and that is when everything works with you. Other problem is that the West has only the capability to build a few power plants year which is to low to really scacle.

  • Brandloyalty Brandloyalty on Dec 20, 2010

    "Plugging in" suggests the hassles of cords and so on, whereas cars could have standardized recharge points so they just "dock" onto the contacts. I don't want to make fun of EV's, but I have to pose the scenario of a particularly dim day when everyone arrives to drive home and their cars are dead. I guess an installation like this would be connected to the grid to provide power when not needed to charge cars, or to charge the cars on dim days. Eventually surplus power could be a revenue generator for the lot owner.

    • Nonce Nonce on Dec 20, 2010

      There is also inductive charging, where you don't need any physical contact to get power, just proximity. If all the cars in the lot were smart enough, they could bid with other on just how much power they want. The guy who lives only 5 miles away will be fine not getting any power on a dim day, maybe even be willing to sell some of his juice if the price is right. (Although I'm very skeptical of such battery-to-grid concepts.)

  • Djoelt1 Djoelt1 on Dec 20, 2010

    A weakness of companies that sell old technology like automobiles is they assume that the rate of technological change that they experience in their product is the rate at which other industries change, and the rate at which new industries can impact their industries. The comments here have merely scratched the surface of what is possible. Once cars with batteries exist, the automobile part is done. The high tech PV, information technology, software, and electronics industry, used to developing products at 10x or 100x the rate of autos, will swing into action. Parking lots are one of the best places for solar panels, and in many areas you could charge extra to have cover for your car. The panels are near the point of use and environmental issues are nil. It's also easily accessible for cleaning. Once the panels are in place, trading of power and other information/game theory driven optimization and trading between cars can take place as an earlier letter writer noted. The group of cars could even cover a temporary grid spike at less cost and at a small profit to the car owner, vs, a peaking power plant. When the grid of information can make real time choices in the flow of electrons, new profit opportunities will drive development we can't imagine now.

  • PeteMoran PeteMoran on Dec 20, 2010

    Transforming our energy use is going to require imagination. I think it's exciting, but I also work in the area so....