France Is Planning To “Pave” 600 Miles Of Roads With Solar Panels


It’s not often that you see a story at Gas 2 inspired by Global Construction Review. In fact, this may be the first. GCR reports that France is working on a project to cover 1000 kilometers of roads with specially modified solar panels. Ségolène Royal, France’s minister of ecology and energy, says, “The maximum effect of the program, if successful, could be to furnish 5 million people with electricity, or about 8% of the French population.”

Wattway solar panels from Colas

This is not some solar sidewalk we are talking about here, folks. This is a major step forward in the greening of the world’s electrical energy supply. According to France’s Agency of Environment and Energy Management, 4 meters of solarized road (about 14 feet)  is enough to supply the electrical needs of one household, not counting heat. One kilometer (0.62 mile) will supply enough electricity for a community of 5,000 inhabitants.

The specialized solar panels were developed by Colas, which bills itself as the “World leader in the construction and maintenance of transport infrastructure.” It introduced its Wattway panels last October. They took 5 years to develop and consist of 7 millimeter thick strips glued to the road surface. The strips use a thin film of polycrystalline silicon to make electricity from sunlight. Colas says they have been tested extensively and can withstand the weight of a 6 axle truck. They are also said to be skid resistant.

Minister Royal says installation of the first Wattway panels will begin this spring. She plans to install 600 miles of Wattway panels over the next 5 years and pay for them by raising taxes on fossil fuels. Royal says the best time to raise fuel taxes is now while prices are low. New taxes would contribute up to $440 million for the construction of her Positive Energy plan.

The idea sounds wonderful, on paper. I happen to live in New England, where millions of pounds of salt are dumped on our roads each winter, local radio stations conduct “biggest pothole” contests every spring, and frost heaves are a way of life. Would a solar highway be able to stand up to such rigors?

Joseph Palmer left this comment to the GCR story: “This really seems impracticable. The electrical panel connections are exposed to pooling water in the rain. The panels are near horizontal, which makes sense at the equator, but loses a lot of efficiency in Northern countries. The surface will be quickly worn by traffic, and will get dirty and scuffed up very quickly. It looks like the panels must be shoulder to shoulder – looks fine on the pictured parking lot, but road surfaces frequently crack and separate, making the mounting surface uneven, placing stress on the panels. We’ll see, but this idea is up against a number of real world problems.”

What do you think about this idea? Would it work in the US if it was limited to states where ice and snow are not a problem? There are thousands of miles of sun drenched roads between San Diego and Jacksonville. If they were all covered with solar panels, they might produce enough electricity to meet much of the country’s energy needs. But wouldn’t it be easier and cheaper to just install conventional solar panels in all the median areas along the way?

Share your thoughts with us in the comments section.



About the Author

I have been a car nut since the days when Rob Walker and Henry N. Manney, III graced the pages of Road & Track. Today, I use my trusty Miata for TSD rallies and occasional track days at Lime Rock and Watkins Glen. If it moves on wheels, I’m interested in it. Please follow me on Google + and Twitter.

  • James Rowland

    Certainly looks more viable than the other solar frickin’ roadways.

    I do have some concerns about what happens with wear, though; it surely can’t be as hard as the aggregate component of asphalt roads.

    Also, will the shedding of abraded material have health consequences to those nearby? Most synthetic composites are not stuff you want to grind up and breathe in, but that’s what will be going on here.

    Not sure I like the idea of a road that can short circuit when it’s damaged, either, especially if it can’t be turned off.

    Really, if you want solar panels along roadways, why not just mount them overhead or to the side? That avoids all these issues, and might even cost less long-term.

    • Steve Hanley

      Great minds think alike, James!

      • James Rowland

        One of the idle thoughts I’ve had while driving along lit sections of the M32 was that street lights might make suitable anchorage for a frame to attach PV panels. You even have a convenient grid connection every ~40m.

        Some consideration would have to be given to stability in high winds, but I think it might work with an optimised design. Maybe if not at the top then lower down and narrower…

        • Steve Hanley

          Combine that idea with making every light pole into an EV charger and you have the beginnings of a great new start-up opportunity!

          • James Rowland

            I’d like to charge from a street light – just not on the M32. 🙂

    • Conrad Dunkerson

      These panels have already been used in test roads and subjected to the equivalent of 20 years of vehicle traffic passing over them without significant wear or damage. In short, they are considerably STRONGER than asphalt.

      Obviously there is no way to pre-test them for decades worth of environmental effects (e.g. daily heating and cooling), but they’ve had test roads for over a year and they’re still solid. There is every reason to think that the covering panels will outlast the underlying asphalt most of the time.

      As to why not put solar panels to the sides or overhead… there is less (sometimes no) space available to the sides of roads, and turning every road into a covered tunnel would be absurdly expensive and inefficient. Snow removal from the elevated platforms alone would be prohibitive. Covering every roof on the planet with solar panels won’t cover our energy needs. Covering medians and ‘right of way’ lands beside roads won’t do it either. But covering every road, driveway, parking lot, and sidewalk? That’d generate several times more power than we use… and just so happen to do so primarily WHERE we use the power (reducing transmission losses) AND allow the road network to replace the power grid.

      As to short circuits… each individual panel is generating negligible current. I’d assume the main power cables will be buried off the side of the road.

      Also note that ‘thin film’ panels like these are essentially ‘printed’ with a spray on technique. So imagine what happens when they eventually develop a large vehicle which can do the ‘printing’ in the field. You just roll down the highway spraying the photovoltaic and protective layers directly on to the road surface. Quick, cheap, and easy.

      • James Rowland

        I see lots of handwaving about the relative costs here, but let’s leave that aside for now.

        You didn’t mention my most serious concern: What exactly ablates off the surface as it wears, and is it likely to present a health risk?

        On further reading, I discovered these devices contain glass. If that’s how the hard-wearing surface is achieved, this could be a problem; glass dust is quite hazardous, mobile and especially problematic if it gets in the lungs.

        Seems like there’s nothing sticky there to prevent dispersal like there is with asphalt, either.

        I also wouldn’t suggest PV surfaces are ideal for parking lots, given that the whole point of these is that vehicles park on top of them. Lightly-used roads and paths? Yeah, sure.

        Speaking of snow, the manufacturer mentions that greater care is required operating snowploughs on this surface. What happens when – as I can pretty much guarantee will happen at the hands of highway maintenance staff – that extra care is not provided?

        Also, what are the consequences of ice jacking for the secure attachment of these panels to the road, or their integrity following damage?

        Yeah, there are a lot of ways this could disappoint.

        • Conrad Dunkerson

          Glass dust – There is absolutely no way that gradual wear could produce clouds of glass dust. At worst you’d see individual particles. No different than cracked windshields, slow environmental wear on building windows, and a thousand other sources of glass in our infrastructure. Complete non-issue.

          Nothing to prevent dispersal – Actually, the whole thing is held together with a resin. Non-issue.

          Parking lots – Even a lot with cars occupying every parking space is still more than 50% exposed to sunlight. Non-issue.

          Et cetera. Basically, your objections run a spectrum from entirely speculative to completely false. Maybe there will be problems with snow plows cutting grooves through some panels… or maybe it’ll be an easy adjustment.

          That said, there will undoubtedly be SOME issues… just as with ANY new technology. They just aren’t likely to be anywhere near as significant as you are claiming given the relative simplicity of this approach and the fact that it has already undergone extensive testing without encountering any of the problems you suggest.

          • James Rowland

            I can assure you that subjecting glass to abrasion most certainly does produce fine particles of dust, and that the passing of vehicles at speed would disperse it into the air.

            If the device is held together with cured resin, that’s not going to do anything about particles that are already free moving.

            50% loss of return is a non-issue? If you say so, providing I’m not paying for that waste. Personally, I’d just do the road and not the spaces.

            Your rebuttals run the range from entirely missing the mark to, well, entirely missing the mark. Got anything better?

          • Conrad Dunkerson

            Something better.


            No number of your contrived reasons that this will not work can ever beat the fact that it already does.

          • James Rowland

            Reality? Yes, let’s take a close look at that.

            You should note that my first words on this topic was that this “…looks more viable than the other solar frickin’ roadways”, but I have stated concerns.

            You have then misrepresented me as someone denying this can work at all, and answered my concerns with assertions that they should be disregarded, largely without any justification.

            Your assertions are not reality. They’re assertions.

            Not very good at this paying attention to reality thing, are you?

          • Rick Danger

            “Parking lots – Even a lot with cars occupying every parking space is still more than 50% exposed to sunlight. Non-issue.”

            Imagine how efficient it would be to put PV covered canopies *over* every uncovered parking lot? Compared to your estimate, that would be more like 100% exposure, and, it would provide shade in summer and shelter from the elements all year round.

          • bioburner

            Solar canopies are a good idea for the reasons you mentioned.

          • Joe Viocoe

            And they could angle toward the actual sun

  • super390

    I’d isolate those on the shoulders and medians. Otherwise, I would rather put a solar roof over the roadway made out of the most inexpensive materials possible. This would allow you to keep the existing surface, and make that last longer. Cars would benefit and have fewer accidents. If we must, we could pay for it by projecting advertisements on the ceiling, but only at red lights.

  • JohnCz

    It does seem like a good use/reuse of developed space and could be a source of revenue for maintaining roadways when gas tax revenue is no longer available. I also question durability but you’d think they ran some pilot projects answering some of the same.

  • FactualBasis

    Its major break through…like putting man on the moon again. Its possible but a lot of challenges. I think its much better with roof houses but its worth to try. A lot get crazy these days. I think next will be the air craft carrier.

  • b3man

    Those solar tiles look fairly shiny and smooth. Driving on them during a rainstorm would be a nightmare. Tires need traction even on a dry road. Smooth and shiny doesn’t provide much traction, or friction for aggressive braking.

    • Conrad Dunkerson

      They aren’t smooth at all and they’ve already been tested in rain and snow.

      • Joe Viocoe

        After years of use, it’ll get smoother

  • This is a poor idea – the list of things that can go wrong, and that will limit how much electricity these will produce – is a long one.

    Just put the solar panels beside the road or above it, or over all the parking lots, and nothing new and difficult and expensive needs to be designed and built.

    • Conrad Dunkerson

      Cars are a poor idea – the list of things that can go wrong is a long one. Just add another horse to your buggy and nothing new and difficult and expensive needs to be designed and built.

      Fire is a poor idea – the list of things that can go wrong is a long one. Just add another animal skin to your bedding and nothing new and difficult and expensive needs to be designed and built.

      • Nope – solar roads are worse at functioning as a road AND worse at functioning as a solar panel.

        Straw man arguments are meaningless.

  • mlhoheisel

    I doesn’t matter whether this tech actually works in more extreme conditions on roads in northern areas for example. The very fact that a competent company is installing them on 1000 km of roads in France suggests they are a decent bet for less difficult conditions and that would be immensely important. Just parking lots and service drives in Sun belt areas without snow would be a revolution. California, Nevada, Arizona, Texas have endless seas of parking lots and paved areas that don’t have heavy truck or high speed traffic. No snow. No salt or plows. Potential for more careful maintenance. The fact that this installs quickly on existing good quality pavement is critical.

    • Conrad Dunkerson

      Exactly. The ‘build a roof over everything and put solar panels on that’ crowd doesn’t seem to have much grasp of construction time or cost. Over the course of the past few years the installation time for solar road technology on a standard parking lot has gone from weeks (for ‘Solar Roadways’ big blocks) to days (for Netherlands concrete slabs with attached solar) to hours (for this Wattway glue on system). Building a roof over the parking lot and solar panels on that will likely remain in the weeks to months timeframe indefinitely.

      • Joe Viocoe

        The “days” is exaggerated.

        It’s not about the speed it can be laid down… As much of the time consuming and expensive work will just be done off-site, like bridge sections.

        It’s still way more expensive to install and maintain, compared to an equivalent system on a canopy.

    • Phil Boswell

      I’d quite like to see what could be done say in parts of Africa, where they could really be doing with decentralised power generation and better roads, and they are not worrying about snow…

  • Xander66

    I would put a solar roof over the roadway. The time consuming and expensive work can be pre-fabed in a factory off-site and assembled like bridge sections. The panels would be cheaper to build and could track the sun. Parking lots with cars parked on them are shaded while cars are present. My mind is open to using this product in limited situations in the south after 10 years of testing proves viability.