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

Re:What could go wrong

[Rei]

Meh, there's a solar bike path in the Netherlands and they don't seem to have excessive problems with dirt. Because rain exists. They got significantly higher generation than they were expecting - only about 1/3rd less than what you'd expect from rooftop mounted panels.

I too have criticisms of the "Solar Freaking Roadways", but let's start with common criticisms that aren't well grounded:

1) They'll scratch up: first off scratches can reduce light transmission but solar panels don't require good "optical quality", only transmission; the light is free to scatter on its way in. It's the same thing that applies to greenhouses - you may have noticed that many greenhouses use "fogged" plastic that you can't see through, yet still lets the vast majority of the light in (in that case, the scattering is actually seen as advantageous). Beyond that, in the case of roadways, I'd think it a given that they'd coat them with a an anti-scratch coat (aka harder than Mohs 7 / quartz sand, the hardest common natural material))

2) Traction: Traction glass exists - it's just surface texturing. They use it for semi-transparent flooring, it's nothing special.

3) "Glass would break and then shred tires": It's easy to make glass bear purely compressive loads (solid objects on both sides of it) without fracture - that's what it's best at. It's shear and tensile loads that glass is bad at, but these aren't applicable when it's flat on a hard surface. And lamination, like in windshields, prevents dangerous shards from coming off in the event of a fracture. This is not an actual limitation.

3) Shadowing: Go to Google Maps satellite view and look up random roads. The overwhelming majority of road surface is completely unshadowed at any point in time. Even in-city roads are overwhelmingly unshadowed. Shadows are practically irrelevant in the countryside except in wooded areas.

4) Costs: The costs of the materials for a road are a minority of the costs of the project, and continue to be a minority of the cost of the project under any realistic pricing for large-scale production of paving panels. A key driver for affordability, however, would be scale: this means large scale production (so road panels are similarly priced to rooftop panels plus the extra glass costs) and continuous paving systems. Anything smaller scale would have elevated costs.

5) "They'd be better on roofs": the main problem with roof installations is there is no way to do mass-scale continuous install (the sort of possibility that paving gives). Each roof has to be handled on its own, with its own engineering issues, with its own project overhead, its own inverters, etc. The key issue to cost reduction these days is getting rid of the overhead; panel production costs themselves have gotten quite low and keep going down. Furthermore, with a road you get "two birds with one stone" - a driving surface and a power generation surface built at the same time in the same space, sharing the same project overhead. It's fine to sacrifice some panel efficiency to glass, shadows, dirt, etc if it reduces your overhead costs.

All of this is not to say that I think they're inherently some sort of great idea that we should dump billions of USD into right this moment I simply think that they do deserve more development and testing, and I have issues with some of the criticisms that have been levied. On the other hand, I do have some issues with the "solar freakin' roadways" people. Number one on my list is the snow-melting concept. It takes five minutes to run the numbers on that and find that it takes way more energy than could ever be considered reasonable. You could melt thin layers of frost off the surface, but nothing of any relevant mass.

If one wants to pursue an anti-snow approach, my personal alternative is having an air bl

Re:What could go wrong

[ShanghaiBill]

I was just going to say that we, here in LA, were going to try this on the 405, but it's always covered with cars.

Here in San Jose, we have solar panels over many parking lots. They generate electricity while providing shade for the cars.

Re:What could go wrong

[Elfich47]

Any given winter will have 50-100 freeze thaw cycles. Once you suggested air blower fails all of the nooks and crannies will get filled with snow and then the freeze/melt expansion/contraction cycle of water will destroy the piece of equipment. I have yet to see a piece of equipment that can stand up to repeated freeze/thaw cycles from a New England winter.

Next up: Snow plows and everything the snow plow pushes in-front of it. A snow plow lumbering along at 20 miles per hour can clear a path 15' wide and a foot deep (often more if it is the truck at the end of plow gang). Any odd ball things in the path of the plow get thrown aside - car parts, baby carriages, clothing, building supplies, will all be thrown aside.

Any portion of the solar panel that doesn't give a clean path to the plow will be destroyed. Any thing dragged along by the snow plow will leave tracks until it is thrown away. "Textured" glass designed to give better traction will get chewed on by the snow plows. If the snow plows leave chips, cracks or divots in the glass: the freeze/thaw cycle of water will attack those imperfections and widen them over the course of a winter.

Until someone demonstrated the ability of those things to survive several seasons of snow plows and freeze/thaw cycles I don't expect to see them where I live. Roadways are designed to be robust and not need a lot of maintenance (exceptions for specific specialty items are to be expected- bridges and tunnels come to mind).

Re:What could go wrong

[Kjella]

A bike lane is nothing like a 50 ton truck in an emergency stop. Asphalt is extremely simple and can't be damaged in any meaningful way. Texturing and coating wears off, asphalt just wears down and if you're going to provide lots of traction as you must then there will be lots of wear. And you can't just make the wear layer thicker without reducing the optical properties. And if the foundation isn't rock solid these slabs are going to start wobbling and crack up like driving over giant tiles. And you can't rally patch a hole with a bit of cheap asphalt, the whole tile must out and be replaced. Cost is the big killer, it's why we don't use more solar today it's not like we covered everything else in solar panels and roads are our last resort. So they produce 1/3rd less energy, involve a ton of tempered, textured, laminated glass encased in concrete with high maintenance and low robustness. Where can I sign up?