France plans 1,000 km of solar roads: enough to make you despair | RenewEconomy

France plans 1,000 km of solar roads: enough to make you despair

France is going to “test” a whopping 1,000 kilometers of solar panels to be installed over the next five years. Are they crazy?


Renewables International


It’s enough to make you despair: French Energy Minister Ségolène Royal has announced the construction of 1,000 kilometers of solar panels, which would be fine if she didn’t plan to pave roads with them. Put solar on stuff, not stuff on solar, y’all (I’m looking at you, Netherlands).

This week, a construction website announced the news in English, but it’s not hard to find it in French either, so it is apparently not a canard. As a part of its “Positive Energy” campaign, France is going to “test” a whopping 1,000 kilometers of solar panels to be installed over the next five years.

Would someone please tell French leaders that putting stuff on solar is a bad idea in terms of power generation – and that solar panels are really bad as road pavement. Solar roads try to kill two birds with one stone, but it is really the other way around: trying to break two stones with a bird.

The French website says that the “plan is to turn roads not only into transport paths, but also into a source of clean and renewable energy consumption without taking up additional space.” (Apparently, there are no rooftops available for solar in France.) Of course, you could just line highways with solar arrays, but that would apparently take up “additional space”; the land adjacent to highways is highly coveted property.

 The best part is the total non-sequitur in the French article. The very next sentence reads, “The transport sector is the prime emitter of greenhouse gases in France at 27 percent of the total.”

In other news, my local filling station now has solar panels on the roof, so my diesel car is now electric…

How is that the Dutch road going?

You may also remember the (stupid) solar cycling path in Holland. The latest news is that the 70 meters of panels are working quite well (report in Dutch). They generated 9,800 kilowatt-hours in 2015, “enough to power three households” (sic). The price tag was 3 million euros (sick). If this article is accurate (or, if you are up for a 30-minute rant, see this video), a meter of bike path should cost around 350 euros. This bike path could have cost around 25,000 euros. The Dutch just paid 2.975 million euros to power three homes.

Of course, that amount does not include all of the attention. Let’s hope it, at least, is priceless, because solar roads are worthless.

Source: Renewables International. Reproduced with permission.


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  1. Alan S 5 years ago

    This sort of sarcastic, sniping article containing absolutely no technical, economic or safety analysis is more appropriate to the Murdoch press than RenewEconomy. The writer simply rubbishes the very concept of solar roads without any factual argument to justify his stance. Statements such as ‘Put solar on stuff, not stuff on solar, y’all (I’m looking at you, Netherlands)’ don’t engender confidence in his objectivity or technical ability.

    I cannot believe that a decision has been made without a study to consider the economic, engineering and safety factors so where is it? An article about this topic in Energy Matters three days ago was much more credible.

    • Craig Morris 5 years ago

      Alan, the article links back to a lot of further analysis. This was not my first article on the subject. And keep in mind that I do not write for Renew Economy, but for Renewables International. My readers there know what I am talking about.

      • Jens Stubbe 5 years ago

        You are not going to get away with blatant dismissal even with links to other dismissing sources. Instead of hanging your hat on what you feel others think then do the thinking yourself. Five years ago quite a few people denied that solar or wind for that matter would ever become economic. Look what that has brought them. Less than a year ago The Guardian started their fossil divestment campaign, which I am certain a lot of investors so wished they had paid attention to.

        I found this previous article, which was also dismissive without analysis

        You have written about the idea before and not gotten any the wiser or analytic about the technology you very obviously do not understand.

        • Coley 5 years ago

          Aye solar is rapidly becoming competitive but if projects like this are put into an average costing and It makes solar look very uncompetitive also gives the denier lobby something to hang their hats on.
          If it was clearly marked as an ‘experiment’ than fair enough, but it seems to be an ‘addition’ to Frances solar capacity.

      • Alan S 5 years ago

        I stand by my statement that this article is not of the standard I expect from Renew Economy – which is where I read it. .

  2. david_fta 5 years ago

    How about if the panels are mounted on an awning above the road?

    • Ronald Brakels 5 years ago

      That is an improvement because the panels can be angled towards the sun and won’t have things on top of them and should be much, much cheaper. But, the supports would still cost more than the racks used in a normal solar farm, the wiring would be more expensive to install, and there are the problems of diesel grime and road dust settling on the panels and people occasionally driving into the supports.

      If one wants utility scale solar, the cheapest way to go about it is to build a solar farm. And France has more land and more sunshine than most European countries.

      But France does not need to build a single solar farm if they don’t want. Rooftop solar has huge potential in that country thanks to the south being sunny and high retail electricity prices. (Yes, French retail electricity prices are high and I don’t want to hear any complaints from Brussels that they are higher there.) They could rapidly expand their distributed solar capacity with the right regulations. Or, as is often the case, without the wrong regulations.

      • david_fta 5 years ago

        Alternatively, they could be mounted on an awning above a cycle path alonside the road, could power LED safety lighting for cyclists, and provide shelter from rain, etc.

        • Ronald Brakels 5 years ago

          Well, if one is going to build a roof anyway there is no point in not building it at an appropriate angle and putting solar panels on it, or using roofing material with PV integrated into it. But when there are roofs already available, that’s usually the most cost effective place to put solar rather than to build a new structure if that structure doesn’t have a significant other use.

          • atheistcable 5 years ago

            One difference is, roofs of homes and business are different from what is owned by state. As solar panels increase in efficiency, it’s easier to replace those over a county/state road.

  3. Ronald Brakels 5 years ago

    Yes, they are nuts. There is nothing intrinsically wrong with the idea of putting solar cells in roads and I’m sure it will be done on a small scale to power sensors embedded in roads and what not, but we are in a race against time to not break agriculture. Oh, and not destroy the natural world as we know it as well. We just got done destroying a chunk of Tasmania with climate change, and I’d appreciate keeping future destroyed chunks to a minimum.

    And because the situation is so dire, we should not waste time on something that we know isn’t going to be cost effective and won’t become cost effective if a 1,000 kilometers worth of money is thrown at it. In a world of scarcity, we need to put the resources we have available into eliminating fossil fuel use now. France has done a great job so far, their CO2 emissions per capita are a third of Australia’s but we’re still all better off, including the French, if they take the most cost effective actions.

  4. Pedro 5 years ago

    Would be better off converting all the street lighting to solar powered LED’s. And no real estate is used.

  5. Objectif Terre 5 years ago

    Do French Solar Roads consume more energy than produced ?

  6. Jens Stubbe 5 years ago

    What is the matter with you?

    While everybody accepts that the idea will work from a technical point of view it is none the less discarded and ridiculed without any analysis at all. Very strange.

    In desert conditions the insolation is attenuated by 40% after one week due to dust covers. You can either accept this or clean the panels frequently. In standard European conditions the dust attenuation is 12% but higher during the summer time where there is less rainfall and more pollen. The lesson to be learnt is that under every condition solar panels will be attenuated by dust.

    Road dust is highly poisonous and should ideally be cleaned off and handled as poisonous chemical waste. Frequent cleaning should enable the roads to perform just fine as solar panels.

    Roads constitute a large area with huge insolation. In Denmark solar in all the roads would provide several times more energy than the country uses altogether and I am not talking grid only.

    Roads are responsible for a serious over consumption of Diesel, Gasoline and electricity as it has been found that the top performance roads result in approximately 7% less energy expenditure than the average roads.

    Road noise is one of the most serious and costly consequences of traffic. Noise exposed people develops cancer, cardiac problems, sleeping problems, depressions and a variety of other health problems. If you can make a case for solar roads you can certainly improve the case by developing a road with active and passive noise cancellation.

    Also the active and passive security can be improved by better road quality.

    Roads are expensive to build and maintain so and in depth analysis of the probability of using solar panels as the road surface including improved performance relative to road friction losses could easily turn out in favor of solar roads.

    Also solar in the roads will free up land for agriculture and nature, and no one could claim that roads gets uglier by being turned into giant solar power plants.

    All in all the anti innovation article is clearly substandard bordering down right idiotic.

    Solar in roads, rooftops, bike lanes etc. is clearly attractive options and may even be cheaper to build than standard roads or at the very least more economic than standard roads.

    • Objectif Terre 5 years ago

      Here – – , we can read: “Wattway can be installed on any road with asphalt pavement (enrobé) that is recent, with no cracks, ruts, deformation, or asbestos. The road must comply with stipulated technical and commercial specifications.”

      In France we have “enrobé” only on highways. Low-cost material (4x cheaper) is used for other roads. Wattway lifespan depends on traffic density, so highly reduced on highways. If we use Wattway on small roads, it will be necessary to add “enrobé” on it, with cost + energy impact. Good quality roads are a good point to reduce fuel consumption of cars, but an economical equilibrium have to be found.

      Wattway = 6€/W. Versus Big Solar PV “normal” plants = 0,8-1€/W.

      354 GW are possible for rooftop solar in France (ADEME study), enough to produce 400 TWh/yr in a country where power demand is 500 TWh/yr.

      The french start-up “Terre & ciel” have developed a Floating solar technology, economicly competitive and limiting water evaporation and green algae proliferation.

      • Jens Stubbe 5 years ago

        Thank you for your information. If it is indeed 6€/W, or that number is just in the initial phase, then the possible other benefits will have to be quite substantial. If on the other hand more innovation and economics of scale can bring down cost the idea may profilate. As a keen cyclist I would love to see the technology implemented for bike lanes where the smoother ride with less road resistance would be great.

        Solar power is going to get cheaper fast, which suggest to me that the concept might fly in a not so remote future.

        • Objectif Terre 5 years ago

          You’re right Jens: 6€/W = initial phase. French INES expect a CAPEX decrease of x2 in the middle term with industrial volumes, and may be x3 in the long-term. So it could comme down to 2€W, versus 0,8 – 1€/W today with standard PV plants, wich cost will also go down in the future. With 2€/W, and with a lifespan hugely reduced + non optimal panel orientation (we are in France, not in ecuador), the LCOE will still be not competitive. A huge gap that in my opinion is impossible to eliminate.
          OPEX are unknown, but changing a panel will requiere to stop the traffic and take more time than with conventional PV easily accessible.

          • Jens Stubbe 5 years ago

            Again thank you for the information you dig up.

            I do see why you find it questionable whether or not the idea will prove economically viable, but since there are a number of positive cost drivers I for one assume that trials are better than continuing in ignorance about the possible potential.

            In the first place the land is free and the solar panels may improve the cost effectiveness of roads along the lines of my previous comment.

            And in the second place utility scale solar consumes land that could be for farming or natural habitats.

          • Objectif Terre 5 years ago

            Yes R&D trials, at smale scale, would be fine…But not investing now 1000 km at 6€/W since it will cost 2700 M€ for just 455 MW (130 W/m2, 1000 km x 3,5m).

            The annoucement of the french minister of ecology doesn’t seems serious for anybody, including INES (french solar scientific center). It seems only political: solar is popular in France and we have presidential elections in just one year (may 2017).

            Cost of land is really marginal for a PV plant: less than 1%. For example the biggest PV plant in Europe, Cestas, near Bordeaux (300 MW) cost 360 M€. 2,6 km2 of land have cost 1.3 M€ (0,36%).

            Do a Wattway road really have better quality (fuel consumption, noise) for cars than “enrobé” road ? I’m really not convinced. Yes, it would be fine to have more technical datas.

  7. Bob Fearn 5 years ago

    Reminds me of the plan to suck up pollute air in Paris and exhaust clean air. Or another good one. Towing jet engines on a trolley with their exhausts tilted down to melt the snow on Charles de Gaulle runways.
    The French seem to have a knack for doing things that don’t take a rocket scientist to disprove.

    • Jens Stubbe 5 years ago

      Good joke there Bob only the scheme to suck up air works just fine and at zero added cost and is being implemented everywhere.

      They are standard in Saab and Tesla as well as for probably all modern building in major polluted cities all over the world and also for many private homes that just enjoyed the extra quality of life and ease of cleaning. Even for municipal scale you use Titanium Dioxide.

      Also modern farm technology cleans methane and ammonia at the source.

      So ridiculing an interesting idea (solar roads) with trying to exemplify with an idea you find silly (while it is obviously not) really backfires big time.

  8. Ian 5 years ago

    We need more technical information here. Are these panels brick shaped? Are they yellow? Are they made in Kansas?

    • Objectif Terre 5 years ago

      “The cost with Wattway is estimated at 6 euros/watt-peak.”
      130 W/m2 (Source: INES PV laboratory)
      3,5 meters wide (Source: INES)
      They want small projects of 20 to 50 m2 to test there product. The anouncement of the french minister of ecology Ségolène Royal is disconnected with reality and only political.

  9. atheistcable 5 years ago

    I like this article. It’s completely on-target. Yes, make all roads into tunnels with solar panels on top. When it snows, the roads will be clear at all times. By shading roads with solar panels on top, that will reduce expansion/contraction and delay the necessity of road repair.

  10. John Ravenhill 5 years ago

    Never been outside Australia I see..Nver been to Holland. Never come up with a great idea hmm. a pathetic article and a Not invented here syndrome..When innovating sir start up cost outweigh benefits Never seen how incubators work I guess..As scale knocks in price will fall and be a sustainable way to reduce co2 output and become a cost effective way to support our hunger for energy..

    • Enzo Canuzzi 4 years ago

      Solar roadways will be always less effective than proper solar installation with more costs involved. You will never be as cheap as solar roof, big solar land or solar on water installations as you need extra engineering for road fitness. You will always have much less effective energy production for physical purposes. You will have higher maintenance coasts. This is not a great idea but a fools one.

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