
France to pave 1,000km of road with solar panels - Udik
http://www.globalconstructionreview.com/trends/france-pa7ve-1000km-ro7ad-so7lar-panel7s/
======
barney54
Here's the HN discussion of this same topic from a few days ago:
[https://news.ycombinator.com/item?id=11001779](https://news.ycombinator.com/item?id=11001779)

------
CyberDildonics
Paving roads with solar panels is a classic example of a 'simple, easy, wrong'
solution. It seems that some people have gross misconceptions about the
barrier to solar panels. People living in crowded cities think there is some
sort of shortage of space. In a broad sense this is of course very far from
the truth. The barrier to solar is cost per kw/hr. As that goes down, solar
installations go up.

~~~
wang_li
> Paving roads with solar panels is a classic example of a 'simple, easy,
> wrong' solution.

You are likely not seeing the same "problem" that the powers that be in France
are seeing. When looked at through the lens of graft, corruption and cronyism,
it's 'simple, easy, and profitable'. Whether it ever delivers worthwhile
amounts of power at efficient costs is entirely secondary.

~~~
hguant
Always nice to know that certain elements of the human condition are
universally true - was just talking the other day about graft, etc in Boston
as compared to DC. Now we can include France in the discussion.

------
StapleHorse
Why would you complicate something so "easy" like putting solar panels on the
side of the roadway? It's going to be so much less efficient for so many
reasons ( orientation, dirt, cars shade, scratches) and maybe dangerous for
the cars.

~~~
mc32
Absolutely. Why not put them on the sides or overhead. Granted overhead adds
cost, but at least there is no abrasion, and virtually permanent shade. Are
they piezo active somehow, why make them part of the roadbed for any reason?

Also wouldn't the surface be less safe for driving in inclement weather,
what's tire grip look like under bad weather conditions with this surface?

Sounds like a boondoggle to me.

~~~
aji
Exactly. Arizona State University recently covered a bunch of walkways and
parking lots with solar panels to both shade the lots while soaking up that
delicious Arizona sun, which seems both effective and obvious. Putting it on
the ground is not the best idea, and not even the most obvious idea. It's just
mind-boggling.

------
brianbreslin
A few things to point out: 1\. putting solar on the ground means that it is
less efficient (cars blocking rays) than raising it above the roadway and
providing shade to the roadway. 2\. Dirt on the panels makes them less
efficient, roads are dirty 3\. Expensive to fix. It is cheaper to fix asphalt
than photovoltaic.

~~~
Retric
That's a poor comparison, it's not about efficency at any one stage, it's a
question of total cost vs total gain. If the cost of this road surface over
it's lifetime is less than traditional road surface plus the equivelent solar
cells over there lifetime then it's a good idea.

~~~
deelowe
Given that asphalt construction is made out of mostly waste materials, is
nearly 100% recyclable, can be patched in-situ, requires very little
maintenance, requires very little skill to install/maintain, and is much more
durable than glass, there's no way the TCOs are even remotely comparable.

~~~
Retric
Asphalt is a product from crude oil; as such it's got finite supply and is
likely to go up significantly in costs over time. It's actually used on roofs
which are becoming less common for various reasons and breaks down in
sunlight.

PS: Nothing says they need to use glass, just a cheap durable and translucent
substance.

~~~
bzbarsky
OK, can you name a cheap, somewhat durable, and translucent substance that's
not glass?

The typical translucent substances people use in practice are various kinds of
glass, plexiglass (not durable; scratches up a lot), transparent ceramics of
various sorts (generally not cheap), gems like sapphire (not cheap, especially
for large-scale applications). Anything I'm missing?

~~~
Retric
Lacquer wood finish comes to mind, though tar is hardly durable. Not 100% on
the specifics but people already use concrete sealant on roads so traction and
cost wise it's in the ballpark.

Don't forget Silicon is really quite tough so your really looking for
something that can sit outside for 20 years vs. trying to protect fragile
components.

~~~
bzbarsky
Silicon is not necessarily tough in the sense of
[https://en.wikipedia.org/wiki/Toughness](https://en.wikipedia.org/wiki/Toughness)
\-- it really depends.

The hard problem in road surfaces is not the sitting outside for 20 years.
Glass, even cheap crappy glass, handles this last just fine; see windows in
houses. The hard problems are dealing with repeated time-varying mechanical
stress and dealing with thermal expansion (windows can play fast and loose
with this by leaving expansion space around the glass inside the frame).

~~~
Retric
Crystal silicon not steel, but it's reasonably close to concrete. And concrete
is the high end road surface vs. asphalt.

Crystal silicon [.6 - 1.3KIc (MPa · m1/2)]
[https://lirias.kuleuven.be/bitstream/123456789/355152/1/Ther...](https://lirias.kuleuven.be/bitstream/123456789/355152/1/Thermomechanical+properties+and+fracture+in+single+crystal+silicon+-+REVIEWED.pdf)
(Page 12)

Concrete [0.2-1.4 KIc (MPa · m1/2)]
[https://en.wikipedia.org/wiki/Fracture_toughness](https://en.wikipedia.org/wiki/Fracture_toughness)

------
pi-err
The "1000 km" title is misleading. The tiles will be mostly installed on
parking space near commercial centers and on a few low-speed connecting roads.

I find it actually a great idea, especially with more electrical cars looking
for plugs at those locations.

Some details and a video on [https://www.aruco.com/2016/01/1000km-routes-
solaires-france/](https://www.aruco.com/2016/01/1000km-routes-solaires-
france/) . The video does show how they think of it for side roads (and don't
say it because PR).

edit: also part of the breakthrough here is that the upper layer is made of
recycled glass and resin and is not slippery.

Bit surprised by the negativity around this on HN.

~~~
ukandy
> The tiles will be mostly installed on parking space near commercial
> centers..

What would possible block the sun from reaching these solar cells...

> I find it actually a great idea, especially with more electrical cars
> looking for plugs at those locations.

Oh yeah.

~~~
pi-err
Their PR is unfortunately low quality and low on facts, though critical
thinking would also try to look at the "why".

The futur or "solar roads" is clearly not highways and express lanes. It's
slow speed, commercial areas - as badly presented by Colas.

For the context, land use in Europe is so different than in the US. Suburbs
don't crawl as much and space is more of a premium.

Thinking at a really local level, for a new retail space like this:
[https://goo.gl/maps/BRkQ5qNyaQU2](https://goo.gl/maps/BRkQ5qNyaQU2) \- the
fields around the center are either here to stay or would be built on.

About 80% of this commercial space is parking lots. It's wasted space. Why not
use it to produce power? Why use additional fertile or constructible terrain
to add solar tiles?

Since 2015, businesses in France also have to build either gardens or solar
panels on their rooftops (new constructions and redevelopments). So that's
turning 90% of space used into something productive or "user-friendly". Again
why not do it?

The pricing of those solar tiles is interesting: 6 euros per max watt produced
on location. Cheap enough - and you get free power for parking users.

It's also great PR for solar to get inserted in people's lives at such
locations.

~~~
ukandy
> About 80% of this commercial space is parking lots. It's wasted space. Why
> not use it to produce power?

You didn't get my point obviously. Parking spaces are to park on. When a car
is on a parking space, it's blocking the light from tiles under it and also
casting a shadow.

> Why use additional fertile or constructible terrain to add solar tiles?

Because they won't have cars park on them. They will also be at an optimal
angle and cleaner.

~~~
KevinBongart
On a parking lot, not 100% is used by cars. Lots of space for driving/walking
through and around.

The example above show the paring lot partially full with a lot of space for
solar panel roads:
[https://goo.gl/maps/ZR5kNMZYGbE2](https://goo.gl/maps/ZR5kNMZYGbE2)

Also, in France, we're limited in farming space. Sure, it's going to go away
eventually, while we outsource farming elsewhere, but replacing fields with
solar panels is not as obvious of a tradeoff as it could be elsewhere in the
world.

~~~
cellularmitosis
Why not just make covered parking, and put solar panels on top? Then you can
just use "regular" solar panels, which will be a lot cheaper, last a lot
longer, and produce a lot more electricity. Plus, covered parking! The
additional structure will be costly, but I wouldn't be surprised if it ended
up being the same total cost as the tiles.

~~~
KevinBongart
Good point!

------
scotty79
Some people on youtube did a bit math and simple home experiments on the
economy of paving roadways with solar panels.

[https://www.youtube.com/user/Thunderf00t/search?query=solar](https://www.youtube.com/user/Thunderf00t/search?query=solar)

[https://www.youtube.com/user/EEVblog/search?query=solar+road...](https://www.youtube.com/user/EEVblog/search?query=solar+roadways)

~~~
thearn4
It looks interesting, but I really don't like watching videos for technical
information. Do you know if they have a writeup on this anywhere?

~~~
scotty79
tl;dw

Horizontal placement, dust, scratches vs brittleness, mechanics of moving load
bearing by tiling vs continuous surface, cost of PV turn it into a joke. We'd
be better off putting them above the roads than on the roads.

------
beat
Gah, what a terrible idea. Making a durable, safe road surface that's also
useful as a solar source? Why not just put a solar roof on the entire road
instead? It'd probably be cheaper, and almost certainly safer and more
efficient.

If we wanted to generate electric power off of road surfaces, why not embed
piezoelectric or some other compression-to-energy mechanism instead? Cars
rolling over the road apply a tremendous amount of physical energy to the
surface. Capture that energy. It's probably more than you'd get from solar.

~~~
mangeletti
> Cars rolling over the road apply a tremendous amount of physical energy to
> the surface. Capture that energy.

This is a misunderstanding of thermodynamics.

There is no energy to be captured without adding friction to the existing
situation. Even capturing the vibration would tax the vehicles traveling over
the road.

This is similar to the old "smart steps" concept[1], which takes extra energy
(beyond the energy already required to take a step) from the person walking on
it.

1\. [http://www.cnn.com/2011/10/13/tech/innovation/pavegen-
kineti...](http://www.cnn.com/2011/10/13/tech/innovation/pavegen-kinetic-
pavements/)

~~~
beat
Of course it adds friction, but that friction could be pretty negligible. You
don't need to capture _all_ the energy introduced by a heavy vehicle passing
over the surface. Just capture a little of it.

~~~
JoeAltmaier
That's just dumb, I'm sorry. There are losses in any process. Any power
generated by this Rube Goldberg idea, would cost far more in lost power to the
car. There is no free lunch.

~~~
beat
Roads already flex and compress in response to the moving weight of vehicles
traveling on them. That's basic materials engineering. Where does that energy
currently go? Thermal loss. Can we convert some of that thermal loss into
captured electricity?

Vehicles are already losing friction energy to roads. This doesn't need to add
to it.

~~~
JoeAltmaier
Power plants like to generate superheated steam to drive turbines. And now we
suppose a tenth of a degree of warming in the pavement is worth going after?

Go back to engineering school for a few more years, is my advice to anybody
trying to get energy out of roads. That potato clock we made in 2nd grade
generates more energy.

------
mapt
So let's take the conservative end of this - 1,000 lane-kilometers.

Assume a lane is about 4 meters. Thus we have 4 square kilometers as a target,
if we assume a square meter of road is exactly as good as a square meter of
dirt.

[http://www.france-agri-
invest.com/property_for_sale/91.html](http://www.france-agri-
invest.com/property_for_sale/91.html) A Stunning Estate of 404 hectares near
Toulouse Price: € 4,130,000 € including all fees

About 1€ per square meter. For farmland on the expensive, 'stunning' end of
the spectrum.

Put it there. Whole program. Forget about the roads. Now you don't have to
shut down FOUR THOUSAND KILOMETERS of active traffic-bearing road, or employ
an army of thousands of installers, or repeatedly install it because it "lasts
up to ten years". You don't have to deal with an extra layer of glass-polymer
tile on top, you don't have to run all of the wiring in the least efficient
and least maintainable manner possible, you don't have to do a bunch of things
that become necessary if you stick it in the road.

1m^2 of solar panel at 20% efficiency achieves about 200 watts at theoretical
best insolation. Solar panels are presently priced around 0.25€ per watt, so
we arrive at a cost of around 50€ per square meter panel, or 50x as much as
the land to place the panels on.

4 million Euros wouldn't be more than a tiny fraction of a program like this.
Using the roads has the potential to increase costs by a factor 10x-1000x over
using simple panels.

------
ukandy
Wouldn't it be simpler to dictate that if you own a commercial warehouse over
xxxx sqm you must install solar panels, or allow them to be installed.

Give large incentives, better rates, it's not like the nuclear industry don't
get a helping hand.

------
JustSomeNobody
Does it rain in France?

That looks pretty slippery.

> Wattway cells collect solar energy using a thin film of polycrystalline
> silicon, but are resistant to the passage of heavy goods vehicles and offer
> sufficient traction to prevent skids.

Ah. It is "sufficient". Okey Dokey.

Edit: Oh, and never let science get in the way of politics!

~~~
draven
> Does it rain in France?

It depends where exactly in France.

As pointed out by other posters it's not the most efficient way of getting
power for various reasons, so this must be mostly motivated by political
reasons.

I _really_ hope it's not slippery at all, I ride my motorbike all the time and
a small skid has more consequences than with a car.

------
downtide
I always think replacing traditional roofing materials with something that
generates solar energy and keeps the rain off, makes for a good idea.

You can get solar tiles, but I have never seen them in the UK. I have seen
houses with panels on top of existing slates/tiles.

~~~
downtide
Another excellent idea I read about was storing solar heat in massive
batteries underground. The battery being made of brick or stone, or earth. You
catch heat in the summer and pipe it below ground, and warm up this
underground store/battery (away from the water table). Because earth is also a
good insulator the heat is localised. And in winter you reverse the process,
drawing out the stored heat.

Roads get very hot in the summer (in some places), and if you could store that
heat for residential units in the winter that may be better than turning into
electrical energy.

~~~
imtringued
Yeah it probably makes more sense to just use this kind of setup [1] except
you ditch the mirrors and just embed the pipes directly into the road vs
putting solar panels on the road.

[1]
[http://www3.epa.gov/climatechange/kids/images/4-1-1solar_the...](http://www3.epa.gov/climatechange/kids/images/4-1-1solar_thermal.gif)

------
maxerickson
More comments here:

[https://news.ycombinator.com/item?id=11001779](https://news.ycombinator.com/item?id=11001779)

I guess they won't really be any different for this article

------
brudgers
Recent discussion:
[https://news.ycombinator.com/item?id=11001779](https://news.ycombinator.com/item?id=11001779)

------
nvader
Maybe as engineers we are tempted to misunderstand the motivation for building
this. As other commenters have pointed out, the main reason for this is
political. Perhaps the secondary reason is not so much the actual utility of
the solar roadway but the visual impact and the meaning that it represents. I
mean, one of the biggest cities on Earth has giant woman made of copper placed
on an island just outside it.

------
hendler
A lot of threads point to the dangers and inefficiencies, as well as political
motivations.

Does anyone know the economics of paving roads with cement or tar per m^2? The
labor and material cost would be transferred and somewhat offset installing
solar elsewhere.

I can not speak to the claims of safety, but I would imagine the decision is
rational enough not to be endangering lives.

~~~
stingraycharles
I would be interested to hear this argument out. This was the first thing that
came to my mind: are there any savings in the costs of the actual road? If you
take those savings into account, what does the net cost / kwh look like?

~~~
ukandy
You still need to build a normal road under the solar panels. They aren't
going to be laying solar panels on dirt.

------
darcyparker
In addition to the efficiency concerns, France should be thinking about the
conflict minerals that are likely in these solar panels. I am supportive of
efforts to reduce energy consumption and alternative more environmentally
friendly energy sources. And it's exciting to hear about new solutions for
energy that appear affordable. But I am hesitant to use technologies that use
conflict minerals. Before we make decisions about buying innovative products
like solar cells, we need greater awareness about the materials they use and
where they are coming from.

------
whiw
This will be a maintenance nightmare. The software concepts of Separation Of
Concerns and Object Single Responsibility might be usefully applied to this
domain.

------
ajnin
Not mentioned is the total cost of the project, estimated at around 2.7
billion Euro for 10-15 years of life expectancy according to the industrial
manufacturer (Colas).

There is a very long way, in France, between political declarations of
intention and actions, so I'm betting this will never be done. Which would
probably be for the best, a predictable failure such as this project would
slow down development of renewables in France even more.

------
tdaltonc
Maybe start with 1km and see how that goes first.

~~~
awqrre
They didn't do any tests first?

------
samuel1604
marketing gimmick me think, there was a bunch of discussion about it in france
and nobody knows if it's very worthwhile

~~~
deelowe
Plenty of people know. The public just prefers to accuse them of being
heretics and corporate shills.

~~~
inflagranti
Anyone who thinks this through a bit must realize that roads are one of the
least optimal places to put solar panels. Solar panels are still not very
cheap so putting them where they are not efficient tips the scale further
against Solar energy. France on the other hand is one of the main producers of
cheap atomic energy. Given all that I cannot see how this can be any more than
a publicity stunt.

------
JoeAltmaier
See this topic (solar roads) is the Perpetual Motion machine of renewable
energy. Folks flock to the idea regardless of the implausibility, regardless
of the massive evidence that is nonsense. And trying to argue is like trying
to argue with a pig; you just get muddy, and after a while you notice the pig
likes it.

------
Nano2rad
Putting solar panels above the road is better. It will also keep road cool.

------
jlebrech
It's the perfect solution for the uneducated to repeat the "fact" that solar
isn't a viable solution, when the implementation is wrong.

on the other hand solar bike paths have has success, but a cyclist is let
likely to break glass than a car.

~~~
alex_doom
Glass bike path when it rain sounds like a death trap

------
EGreg
It reminds me heavily of this:

[http://youtu.be/qlTA3rnpgzU](http://youtu.be/qlTA3rnpgzU)

------
kumarski
Did Indiegogo pay for this site?

------
uremog
a.k.a, one megameter, or mm, no wait... that's already... uh....

~~~
rconti
Was on a long motorcycle trip with a few friends. We had left our home in the
US and were traversing Canada which, of course, uses the metric system, unlike
the US.

As we passed one sign, it said something to effect of "Dawson City 1500km",
which I remarked on over the radio as it was a nice round number (and, of
course, quite some distance, and a large number you're unlikely to see on a
road sign in the US due in part to the greater length of the mile).

My buddy chimed in "ONE POINT FIVE MEGAMETERS"

We laugh about it to this day.

