France To Pave 1000km of Road With Solar Panels (solarcrunch.org)

An anonymous reader writes: France is planning on a project to build 1000 kilometers of road with specially designed solar panels. This project will supply 5 million people in France with electricity if it is successful. Though many solar experts are skeptical of this project, the French government has given the go-ahead to this venture. According to France's minister of ecology and energy, Ségolène Royal, the tender for this project is already issued under the "Positive Energy" initiative and the test for the solar panels will begin by this spring.The photo voltaic solar panels called "Wattway" which will be used in the project are jointly developed by the French infrastructure firm "Colas" and the National Institute for Solar Energy. The specialty of "Wattway" is that its very sturdy and can let heavy trucks pass over it, also offering a good grip to avoid an accident. Interestingly, this project will not remove road surfaces but instead, the solar panels will be glued to the existing pavement.

Comments

What could go wrong

[kamapuaa]

So basically the plan is to cover the pavement with glass, that will need to stay clean to let the sunlight through. I see no possible problem with any of this.

Re:What could go wrong

[Rei]

Even in heavy traffic, the overwhelming majority of the road is exposed. And yes, that's the 405, in a high traffic area.

Re:What could go wrong

[Rei]

Like how hold concrete becomes slippery? Yep, just like with concrete, you need to resurface. But one expects them to use anti-scratch coatings, which would significantly reduce the rate of wear. The aggregate in typical concrete can be up to Mohs 7, but the cement is only Mohs 2-5. Raw unprotected glass is Mohs 5-6,5, but scratch resistant coatings can raise it to over 7 to avoid being scratched by quartz sand.

Re: What could go wrong

[orlanz]

We could put it on all downhills in a certain grade range. Steal power from the brakes.

Also local roads with traffic that burn gas inefficiently should be ok too. They don't run the engine efficiently so stealing some excess power should be ok.

tl;dr

[Anonymous Coward]

RRV #632 for the tech. For the political sorts, this is what happens when you have a stupid EU policy requiring the state to pay private companies to build infrastructure rather than employing their own talent.

Why not a roof?

[JoeMerchant]

Wouldn't it be more effective to build a "solar roof" over the highway, shading motorists during the hottest parts of the day, angling the panels to maximize insolation at the latitude, and for f's sake: not having to make them sturdy enough and grippy enough to safely drive trucks on them?

How long will this roadway last, and what will be the replacement cost? I mean, if this miracle surface can stop potholes from forming, then, yeah, let's put it everywhere, but I'm not feeling like that is the case.

Re:That is a REALLY BAD assessment

[Rei]

What road do you live near where the surface is packed full of rubber tire marks? Must be pretty miserable to live there, with people burning tires all the time.

A solar panel is in fact an EXACT OPPOSITE of a greenhouse - the greenhouse relies on IR alone,

Hahahaha.... oh geez... :)

Let's back all the way back to third grade and cover the topic of "photosynthesis". You see, plants need light from the sun to grow! Now class, take one of those seeds you sprouted and put it on your windowsill, and put the other in the closet... we'll bring them back to compare in two weeks. Don't forget to water!

The amount of light transmission is probably the biggest factor in greenhouse design. Here in Iceland people have to use glass (most common) or hard plastic (less common) because of the wind, thin plastic hoop houses don't survive here. Most commonly used is single pane glass. Yes, you read that right. Here in a country with "ice" in the name, it's still considered worthwhile to let the heat pour out of your greenhouse in order to get a few extra percent sunlight. Now, we have hot water for heating which reduces (but doesn't eliminate) heating costs, but still, it drives home the point: to growers, light equals growth.

Greenhouses most definitely do not rely on "IR alone".

If you're curious as to why fogged surfaces are often seen as desirable in greenhouses - it's because of shading. Fogging only causes the greenhouse to lose a couple to several percent of the light (depending on the type of plastic or glass), but it means that all of the light is no longer coming from the same angle. This helps get light to leaves that would otherwise be shaded by other leaves.

Ironically, contrarily to what you wrote, glass-covered solar panels do care about IR transmission. They don't generate power from IR, but their efficiency is correlated to their temperature, and the temperature is correlated with the radiative equilibrium of their environment.

Why roads?

[Firethorn]

Okay, first up: I analyzed the 'Solar Freaking Roadways!!!' proposals so I know the arguments, though I think they glossed over or ignored numerous problems. My end thought was that it might be a neat system for a pedestrian walk area, where you don't have anything bigger than a golf cart traversing it.

That being said, I'm always willing to be proven wrong - it's relatively easy to get me to agree to a 100m/1km/1 Mile or so 'test strip'. 100m, for example, is long enough to get a truck completely onto the solar surface and drive for a bit - because the interface might be a destruction point. Something to study, obviously.

Okay, the reasoning for 'solar roads' is a combination of displacement and synchronicity. By displacement, we mean that the surface of a properly constructed solar panel displaces other construction material - pavement, for a road. For something like a 'solar car park', solar panels are strong enough to replace the roof, not supplement it.
- Problem: Pavement is relatively incredibly cheap and durable.
Synchronicity: By this I mean that the substitution provides additional benefits. Solar roadways, for example, boasts that you could incorporate heating elements into their units such that when it snows you can avoid the need for plowing by melting the snow off the roads, then recoup the heat used via the solar panels. Problem - I don't think they've thought about heavy snows and that you get less light in winter.
Another 'benefit' would be using LED lighting to enable 'remapping' the control lanes on a road, signaling when it's safe to pass, etc...
They even said that the solar roads would be easier to repair - have a busted hexagonal panel? Pull up with a truck that has a robot arm that automatically unbolts and lifts the damaged panel and locks a replacement in. Each panel is supposed to be cheap because it's made in an automated factory.

As such, using the panels as 'roadway shade/shelter' such that things like rain and snow don't reach the road at all, and probably even block direct sun, is a much better use.