Question: "What surface or environment -- by virtue of having no control over shading or solar angle, and by maximising dirt, wear-and-tear, and difficulty of maintenance -- is more or less the worst place on earth to mount photovoltaic panels?"
I mean, I know that roads occupy a stupid amount of surface area, and I understand the desire to do something better with that area. (Tip: just build less of them.) But seriously, as far as solar panels are concerned, they have nothing else going with them.
During the day, when the sun shines the brightest the roads will have the most amount of traffic, shading the panels from the sun. Doesn't make sense to me.
Why not just spend this money and put solar panels on industrial buildings or state owned buildings?
Most roads don't have much traffic - with a 3 second gap between each car and the cars going at 60KM/hr, the vast majority of the road will be open at any one time. And obviously, when the sun's high up the shadows will be the smallest.
>Why not just spend this money and put solar panels on industrial buildings or state owned buildings?
Proof of concept. Varying solar tech research to find unexpected gains. Maybe it turns out that putting solar panels on roads is actually extremely cost-effective, when you properly adapt the solar panels to road conditions?
There is a lot more area coverage in roads than state-owned buildings. Convert all roads and you can easily power the entire country many times over. If the government is going to foot the bill and make solar power happen immediately, roads have the advantage that they are immediately available land for solar generation. Build solar off-road and you have to choose between a legal battle of evicting civilians from their private property, or destroying government-owned nature reserves. Convert roads and you conveniently dual-purpose existing land area while minimizing environmental impact.
> "There is a lot more area coverage in roads than state-owned buildings"
and there's a lot more area coverage in state-owned buildings without solar than in state-owned buildings with solar, or that will get solar in a reasonable timeframe. It's not like we're running out of rooftops and need to find alternatives.
Even if the government did manage to cover all of their rooftops, there's still plenty of residential rooftop area that can easily be converted with proper incentives. I'm pretty sure we can generate enough solar power to handle all of the needs that solar is suitable for before we come anywhere close to running out of rooftops.
Even if I'm mistaken about how many open roofs there are and how much solar capacity they could handle, there are a lot of other and better options before you get to "put PV cells on the ground underneath semis".
imo it would much smarter to try to extract heat power from roads rather than solar power.
I always thought that in warm countries they should install piping under the roads with water that would get heated and brought to boiling thus generating electric power.
Here is idea, instead of building stupidly expensive road that will most likely generate little power - just provide 75% grants to all that want to install solar panels, wind turbines or solar water heaters at their property. Problem solved.
Solar panels are getting less expensive, but they are in no way "cheap" when compared to traditional road construction materials (concrete or asphalt).
But can the panels survive a snow plow? If not, you're limiting it to perhaps(?) half of France. Yet everyone in the entire country pays for it with the gasoline tax.
Interesting analysis -- although his numbers actually go off-track in a number of places. The flubs the math on the maximum power output (it's actually about 20% worse than he estimates) while making too strong a case against LED lighting (you can use reflective baffles to send the light at the appropriate shallow angles; there's no need to waste energy projecting lane-markings straight up. Also, an "intelligent" road which presumably has built-in car sensors needn't project lane markings indefinitely -- just a few hundred metres in front of whatever cars are present. During low-traffic periods this could save a lot of energy).
But all of that is beside the point. What's interesting is that in his analysis, he makes the same mistake that the solar roadways people make (and which I've just made here), of chasing technical details too far down the rabbit hole. That's just not necessary: a simple financial analysis leads to a much quicker and more certain refutation.
For any given amount of money invested, you can either build A.) a solar roadway, or B.) a conventional roadway plus a solar farm. If the LTV (lifetime value) of A is greater than the LTV of B, then A is a good idea. If it isn't, then it isn't. It took me about 5 minutes of high-level analysis to conclude that the LTV of solar roadways was orders of magnitude worse than the LTV of conventional roads + solar farms -- sufficiently so that no amount of technical fiddling would ever close the gap. That's pretty much the end of the story.
That's enough for all right thinking people to agree it's a dumb idea but not enough to convince someone who isn't well versed in the field. For that, you need to go into far more detail.
I mean, that's cool and all. But why build the road surface out of fragile panels? Why not just build a regular road and provide it cover with a roof made out of panels? Now drivers get to drive in the shade and it's probably less expensive.
Even cheaper, just put the panels up along side the road, perhaps on shoulders or other already owned rights of way.
Even cheaper, just give the money to everybody so they can put panels and batteries on their houses and businesses and over parking lots.
This is asinine for all the reasons others have already stated. The only place solar panels could make sense is on the road shoulder. Even then they need to be robust enough to handle having an 18 wheeler park on them. Or you only make them strong enough to park cars on them and replace them when 18 wheelers do need to stop on them with the savings earned from not over-engineering them to withstand 18-wheelers.
That said, I do think roads are a prime place to combine with energy distribution infrastructure. On top of energy distribution, we don't need cars with batteries if they can instead function like slot cars getting their energy from the road surface below. This greatly reduces the weight of cars such that they are much cheaper to accelerate and decelerate and the stored kinetic energy is much lower making them much safer. Basically roads need a safe "automotive third rail". PG&E in California in partnership with the California DoT is the ideal company to pioneer this approach.
Moving batteries around is great short term, but long term we really should be electrifying roads.
From the original article, it appears the French are not the only ones embarking on the "romantic and pointless" project.
The Dutch are in on it too, though on a smaller scale. And over here in America (Idaho to be specific), http://www.solarroadways.com has won a $750,000 contract from the USDoT for something similar.
Because anything S. Royal says is pointless. She's notoriously incompetent on every subject she talks about and she doesn't care about being incompetent, since she believes that her irrelevant condescending babble will hide the fact that her knowledge is non-existent. She constantly dodges questions, and in her case, that's not because she is afraid of showing her true intent, that's simply because she has no idea of the answer.
She is as cocky with her associates and staff as she is in public.
She is famous for cancelling projects or orientations she supported in the previous years of months. She is is a minister of ecology who does not do a single thing for ecology, on the opposite she cancels what was launched, and it is not even the kind of cancellation that saves money, but it is the kind of cancellation that costs billions.
If a company proposes her something shiny, useless but shiny, she will promote it if that means she can be in the light. This stuff here will be probably be abandoned after a few months or years, if it ever works in a satisfying way.
You're putting an expensive functional product in a location that guarantees a much shorter lifespan. Take the same panels and put them on rooftops, empty fields, practically anywhere else reasonable you can think of and you will get lots more electricity out of them because of longer life.
Longer life, better solar angle, less shading from vehicles and surrounding trees and buildings, less deposition of sunlight-blocking dirt and grime, easier access for cleaning and maintenance, etc. etc. etc. etc. etc. etc. etc.
Because roads that carry a lot of traffic will need resurfacing before the solar panels have reached their economic break even point.
There are a lot of bull-shit renewable energy projects, which is a real pity because there are also a lot of good ones and the bad ones give all of those projects a bad rap.
I don't know if this project is bull-shit or not. But a big part of solar electricity cost is installation cost and emplacement cost, not the solar panel. By using "free" space and installing those panel while building/repairing the road we can save on those two important cost.
The question is : is it enough to offset the drawbacks ?
On the other hand, if they do it piece meal and are willing to back out if the initial phases don't succeed, what better stress test for the material do you want?
Go for it. My $0.02: complex shading and frost damage as well as water getting into the system, overload from excess weight vehicles and so on seem to me to make the roads the very worst spot where you'd want to place a solar panel. Unless you place them on the sound barriers in Urban zones (and there you're going to have a reflection issue impacting safety).
Check out Dave on his EEVblog on YouTube he has a scathing Solar Roadways review. Solar Roadways is a similar concept only they wanted the panels in the road itself not off to the side but the same mistakes apply to both.
This is asinine for all the reasons others have already stated.
That said, I do think roads are a prime place to combine with energy distribution infrastructure. On top of energy distribution, we don't need cars with batteries if they can instead function like slot cars getting their energy from the road surface below. This greatly reduces the weight of cars such that they are much cheaper to accelerate and decelerate and the stored kinetic energy is much lower making them much safer. Basically roads need a safe "automotive third rail". PG&E in California in partnership with the California DoT is the ideal company to pioneer this approach.
Energy distribution is actually a power company's biggest strategic asset and they should be focusing on this, especially in the face of a world where energy production is being massively distributed through such approaches as home solar.
Moving batteries around is great short term, but long term we really should be electrifying roads.
Great. What a lovely waste of money. It's the "solar freaking roadways" bullshit again. No, making roads solar panels is not a good idea. At all. End of story. It's always a better idea to spend the money on a solar farm.
1. Road surfaces need to be resilient to grit and large trucks driving over them in rain and other shitty conditions. Glass is much softer than rocks, and it will undoubtedly crack eventually in the constant heating and cooling, not to mention tree roots and all the other issues that fuck up asphalt. Not to mention you'd need to clean (or replace) the panels so often you might as well make the roads out of gold.
2. In order to actually get the power from the solar panels, you need an energy grid that is as big as the road network (this isn't a big deal for small rollouts, but it is an important note to make). In almost all countries, this is simply impractical (the electricity network is several times smaller than the road network) and would be an enormous waste of money for very little gain.
3. Solar panels are already about 30% efficient at best. However, that metric only applies for solar panels being hit with direct sunlight. If you lay your panels flat on the ground (and not on rotating sunflower-like angled panels) you lose yet another third of the amount of energy you could've gained. Why? What was the fucking point of that?
TL;DR: Please just build solar farms and stop trying to reuse the road system for something it wasn't designed for. You're just wasting taxpayer's money.
To be fair, that was the fourth solar farm planned to be built juuuust far enough outside the town that they weren't getting paid for it or able to use the electricity generated.
•Shading. Cars don't occupy 100% of a highway, even when it's stopped bumper-to-bumper. The faster cars go, the larger the gaps between them. For PV, the recovery is instantaneous, and for a large road surface, the power output flat and steady in spite of car movement. The most sunlight will come in from the best angle during the noon hour, when roads experience little traffic. Morning and evening rush hour usually suck for sunlight to begin with (the sun's lower in the sky), so even bumper-to-bumper shading wouldn't be taking much away from the total.
•Dirt. The technical term for dirt on a solar panel is "dusting". It's a factor, and even in places where it rains mud on occasion, a pretty minor one. The rain eventually washes most of the gunk away. A much more significant factor would be heat buildup. PV's put out more power the colder they are. On rooftops they can convect that heat away. On road surfaces, not as much.
•Ruggedness. Having broken more solar panels than anyone I know, I can attest that a PV road surface can be done right. Cars don't jump Mario-style on surfaces but rather apply predictable compression and shear stresses that would have about as much effect on the tempered glass surfaces as your windshield wipers do on your windshield. Even a shattered solar panel still works almost as well as a new one, believe it or not. The silicon cells themselves have a diamond crystalline structure and are tough as nails in compression. If you somehow managed to bend a cell 90 degrees then it would end badly, but that's simply not happening on this road.
•Solar angle. These won't win any awards for most power output of a given surface area of solar panels, but per hectare of land, they're probably just as good as any system. All the sunlight incident on that hectare will hit a solar panel. Given how cheap solar panels are now (<$1/W), and how expensive an urban road is ($2000 a linear foot!), the solar road competes not against a solar rooftop installation (15% efficient) but against a conventional road (0% efficient).
•Economic gotchas. The biggest concern I have with this approach is the balance of system- the miles of copper wire, the mounting hardware, the inverter assemblies, and the places to store and access them outside the weather. Inverters wear out after X years, and so the question is at what point is it just more cost-effective not to replace the inverters? French electricity will probably justify it, but maybe not Pacific Northwest electricity (where cheap hydro keeps it ideal for heavy power users).
•Heat vs. Electricity- Let's face it. We run on electricity to a far greater extent than low-grade heat. Saving a few kWh from cooling and warming a building using stored heat from a roadway is great, but it's a drop in the bucket compared to what that space probably uses in electricity. You can swing the temperature in that building by literally thousands of degrees with electricity, whereas a couple dozen is the most you can hope for with heat capture. Electricity can be dispatched thousands of miles away along existing infrastructure, but that waste heat is limited to a few thousand feet at best.
•Wheel Grip/Slippage [edit]. Conventional PV's have a flat surface since that's how glass is most cheaply manufactured. If modules are small enough (apparently these aren't) then a tile/lowered grout approach will still create a rough enough surface to allow for reasonable braking distance. Glass is really hard to create coarse surface roughness in when transparency must be maintained, so I'd be concerned that minimum braking distance would be increased. Icing conditions would be particularly concerning.
"have about as much effect on the tempered glass surfaces as your windshield wipers do on your windshield."
And this is where you lose me. Either you've never seen a tempered glass surface, or you've never seen a road, or maybe you just have no idea why roads are built of the things they're built of.
Asphalt is a pliant surface made of viscous hydrocarbons and filler that slowly stiffens up over a period of years. You can scratch it, you can embed pebbles in it, you can heat up the center twenty degrees warmer than the edges, you can run a metal snowplow over it, you can press furrows in it until some parts of the road surface have 30 degrees of divergence from other parts of the road surface. To some extent it's self-leveling, balancing out physical distortion in one spot with physical distortion in another spot five seconds later.
The way you cut glass (at least, without a specialist sawblade) is by scratching it and then applying pressure. The crack propagates and it shatters into two pieces. This doesn't work with tempered glass at all; The surface is under so much tension that it tends to shatter into many pieces instead of two. Roads don't get scratched as exceptional events - it happens many times a day, with tires, steel bits hanging off, but most problematically, with quartz pebbles (harder than glass) embedded in tires. Go look at your tires; Rub your finger along the surface. Now rub your iPhone along that surface.
Melting glass and transporting it in whole sheets is energetically very expensive. Installation is extremely difficult. Wear characteristics are not only unworkable, the glass would rapidly become frosted and translucent.
If it was economical to make roads out of glass, we would be doing it. It's not even economical to make them out of concrete except in isolated circumstances.
Roadway solar panels are a laughably bad idea. Green inventors are condemnable when they waste our very limited enthusiasm for green ideas on obvious technical nonstarters. I've been watching this space for more than a decade and I'm beginning to despair at the ratio of design/architecture student renders to even back-of-the-envelope engineering effort.
> "Given how cheap solar panels are now (<$1/W), and how expensive an urban road is ($2000 a linear foot!), the solar road competes not against a solar rooftop installation (15% efficient) but against a conventional road (0% efficient)"
It competes against conventional road + solar rooftop.
I don't think it will ever be price-competitive or efficiency-competitive with doing both things separately.
On their website (google for wattway, and go to the FAQ) they say that the panels have an expected price of 6 EUR per peak KW, so much more than your 1$ figure.
I would love to hear more details about why folks don't like the idea. Let's suppose the solar panels are durable enough for heavy vehicles to drive over, and modular so as to make re/placement reasonable. What are the real problems?
Most don't believe there's a positive ROI. Panels need to stay clean. I personally think the business model for these is to get Governments to install them for PR reasons (using public funding).
Let's suppose the solar panels are durable enough for heavy vehicles to drive over, and modular so as to make re/placement reasonable.
There is no way its durable enough to not be scuffed and offers a safe level of grip in all weather conditions, and is transparent enough to offer anything near a normal solar cells efficiency, AND is cheaper than just building a regular road and installing a solar panel that doesn't get driven over.
I also feel like most people here are criticizing without having read the article. It is clearly stated that this will leverage a new technology to protect the photo-voltaic cells and make the panels very resistant to heavy-weight.
Someone tell them to read the hyperloop whitepaper, that way at least the solar panels won't be wasted on the ground, and they'll be at the cutting edge of train like things again.
How about they experiment on 1 km before 1000 ? I'm very dubious that this can work, so before they burn my taxes on this kind of things I'd rather they prove its usefulness.
That's exactly what they are doing. The article is lying, the only thing that was decided is to test the new technology before kicking off the 1000km project.
Answer: "Roads."
Question: "What surface or environment -- by virtue of having no control over shading or solar angle, and by maximising dirt, wear-and-tear, and difficulty of maintenance -- is more or less the worst place on earth to mount photovoltaic panels?"
I mean, I know that roads occupy a stupid amount of surface area, and I understand the desire to do something better with that area. (Tip: just build less of them.) But seriously, as far as solar panels are concerned, they have nothing else going with them.