Four years ago a viral campaign wooed the world with a promise of fighting climate change and jump-starting the economy by replacing tarmac on the world’s roads with solar panels. The bold idea has undergone some road testing since then. The first results from preliminary studies have recently come out, and they’re a bit underwhelming.
A solar panel lying under a road is at a number of disadvantages. As it’s not at the optimum tilt angle, it’s going to produce less power and it’s going to be more prone to shading, which is a problem as shade over just 5 per cent of the surface of a panel can reduce power generation by 50 per cent.
The panels are also likely to be covered by dirt and dust, and would need far thicker glass than conventional panels to withstand the weight of traffic, which will further limit the light they absorb.
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One of the first solar roads to be installed is in Tourouvre-au-Perche, northwest France. This has a maximum power output of 420kW, covers 2800sq m and cost €5 million ($8 million) to install. This implies a cost of €11,905 ($A19,230) per installed kW.
While the road is supposed to generate 800kWh/day (kilowatt hours per day), some recently released data indicates a yield closer to 409kWh/day, or 150,000kWh/yr.
For an idea of how much this is, the average home uses around 10kWh/day. The road’s capacity factor — which measures the efficiency of the technology by dividing its average power output by its potential maximum power output — is just 4 per cent.
In contrast, the Cestas solar plant near Bordeaux, which features rows of solar panels carefully angled towards the sun, has a maximum power output of 300,000kW and a capacity factor of 14 per cent. And at a cost of €360 million ($A581 million), or €1200 ($A1938) per installed kilowatt, one-tenth the cost of the solar roadway, it generates three times more power.
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Several of their SR3 panels have been installed in a small section of pavement in Sandpoint, Idaho. This is 13.9sq m in area, with an installed capacity of 1.529kW. The installation cost is given as $US48,734 (about $A67,000), which implies a cost per installed kilowatt of $A44,420 more than 20 times higher than the Cestas power plant.
And this is before we look at the actual data from the Sandpoint installation, which generated 52.397kWh in six months, or 104.8kWh over a year. From this we can estimate a capacity factor of just 0.782 per cent, which is 20 times less efficient than the Cestas power plant.
h/t to Ozspeakup
Dylan Ryan is a lecturer in Mechanical & Energy Engineering at Edinburgh Napier University.
This is not in the least surprising; what is surprising is that anyone thought for a moment this could be a good idea. Road surfaces take an incredible beating over time — just take a close look at one five years old or more and the cracks and dips a plain to see. Collisions, spills, frost damage and subsurface water erosion accelerate the process. Even roads in good shape are constantly being torn up to fix buried pipes or improve drainage. The cost of adopting a road surface which is at least 100 times more expensive than asphalt to install and maintain simply cannot be made up, even with the most optimistic estimate of power generated.
Or the way I put it, if local governments cannot afford to maintain current road infrastructure, how will they ever be able to keep up with this? It’s obvious that it won’t be funded by all of the “free” electricity that these things will supposedly be generating.
And roads in the Northern states get snow, ice, salt, and plows. This is not good for cars, let alone electronics.
I wonder how much of that harden glass surface becomes harden glass splinters after a few years?
Where is the ecological impact study?
Only the greens or the Left could come up with an idea as stupid as embedding solar panels in roads. It just boggles the mind.
When your taxpayer funded/subsidized, pipe-dream program fails, you obviously haven’t spent enough. Let the writing of new grant applications commence!
“They had fun, fun fun until the gov’ took their T-Birds away”
Despite his political stances on Brexit/cAGW, youtuber “Thunderfoot” has done some excellent videos on this particular stupidity.
When in a less generous mood I sometimes think that they should have a “solar roadway” day every year, just so we can keep track of the congenitally gullible who need medical help.
The question is, why did ANYONE ever think this was an idea even worth studying?
The level of stupid required to think that burying solar panels in roadways was a good idea is incredible.
Presumably they were hoping to make expensive land “dual use”, but that only applies in the cities, where those roads are covered in cars and shadowed by buildings. So a silly idea.
On country roads, you’d have to be mad to want panels in the road surface as land is cheap and properly inclined cheap to install panels would be far more economical.
So there literally was no use-case to justify this but it still received millions of taxpayer funds because it was “green”. We really have reached peak stupid.
The level of stupid needed to promote that idea is reached by Ségolène Royal:
– mother of former French president François Hollande’s children,
– former minister of education,
– former presidential candidate (lost to Nicholas Sarkozy),
– former minister of of “ecology, sustainable development, energy”.
Idk harry, there doesn’t ever seem to be a peak to stupid. Just when you think you’ve found the peak of stupid an even higher peak appears just a little further along.
Wait, don’t cars cover the roads much of the time, since roads ARE for cars? Have these visionaries really figured in all the shadowing from all the cars that actually use the roads? And all the dirt and scratches? And all the weight? And all of the costs to keep solar roads clean enough? And the repairs?
Could people hijack the power, to save paying their electric bill? What security threats might they pose? (I have no idea at present, but just wondering)
Forgive me, if I am not enthusiastic about solar roads. They seem like a ridiculous idea.
Colas says that cars only cover 5% of the roads. That’s believable, this isn’t some street were cars are waiting at an intersection. Shadowing by cars isn’t the most serious issue IMHO.
The other issues, like dirt, scratching, vibrations, and thunderstorms are not remotely tractable: not by today’s technology, not by tomorrow’s technology. That they had a noise problem suggests strong vibration issue.
car shading is the least of the issues (and is variable depending on how heavily travelled the particular road is). Dirt is probably a bigger issue in regards to blocking the sun as roads accumulate dirt and debris quite easily. Not to mention environmental shading (buildings, trees, snow, etc) There are parts of my street, for example, that take forever to melt when it snows because there are large trees on both sides of the road blocking most of the heat of the sun from reaching the road surface (ie it’s well shaded throughout the day). Many city streets with skyscrapers on both sides similarly suffer from such “perpetual shade” limiting how much solar energy reaches the street surface. And a foot-deep snowstorm will bury those suckers quick as can be.
This is actually a shame. This would have been a nice power generation scheme for road lights and such.
Ha-ha-ha!!! Too funny!
Unicorn farts would also have been a nice power generation scheme. But both schemes have 1 thing in common: they are unworkable for obvious reasons.
Doy! Never in the history of 21st Century stupidity was such a half-assed idea so obviously unworkable. One look is all it took. The trougherati were at it again.
In all Internet blogs, forums I went to, that solar road concept was harshly criticized by proponents of solar energy: they simply don’t see the point of putting PV cells there.
Many areas are available to put PV cells in France at a lower cost and easier access for maintenance, starting with building shades for parking lots.
They forget to mention that the speed limit had to be lowered as the “solar road” was very noisy.
I wonder what that means in term of wear on wheels and the cost for car owners, who are more than paying for the road maintenance in France! But the French infrastructure is crumbling (except the privately managed highways). At least we have as many rotaries as the rest of European Union.
“Only” 5 % of the panels had to replaced after one year according to Colas. That “one year” being the FIRST YEAR. Oh my.
This kind of road only works in “The Land of Oz”!
I remember the previous posts here on the solar road/pavement, and I don’t recall one comment in favor of this idea as having absolutely any merit. It was stupid from the get go and the negative result is just a confirmation that it was even more stupid than the general population probably believed. Of course, it was good for a Friday Funny and all the ridicule one could muster. Just bizarre that something like this would get built. Probably a computer ‘model’ could have predicted the same result. Maybe if it were a covered bridge, and the solar panels were on the roof that was being built anyway, to provide lighting or some other critical application etc, then that may be more efficient than this hair brained scheme. What were they thinking/smoking?
I did see one place with solar panels for electricity and hot water on an South Pacific island near the equator that did make a lot of sense. The electricity pricing was about 25 cents/Kw/hr USD, and often suffered unpredictable rolling blackouts. The hotel had 30 200 watt panels along with some glass solar evacuated thermal tubes for hot water. Each hotel room was fed with a separate 3 amp dedicated circuit from a central inverter (220 V 60 cycle) so had the capacity for maybe 660 watts, but was only for a small efficient inverter fridge, LED lights, the internet modem, and the Sat TV. And a plug for a laptop and charging things. These were on 24/7 with this dedicated system, so maybe it was 350 watt load if everything running at once. There was a bank of old submarine batteries in a central location that had been scrounged and there were 3 pure sine wave 2 Kw inverters for the 12 rooms on the 3 amp circuit breaker for each room so if you plugged in your hair dyer, it would trip. It worked perfectly for the application, since they also had a battery charger that ran off the mains, or a back-up generator if worst came to worst in a monsoon for a week. The hot water was a gravity solar tower, so was always warm or hot water and the place was completely livable with amenities even if the utility power was off. The hotel kitchen was all fitted too, and had propane for a gas range. Except for A/C, unless they fired up the generator. The owner said he had a pay back of about 6-7 years on his entire costs, but the real beauty of this was that the hotel rooms had stable power for the smaller electronic loads that nobody likes to go without. Which made his place the most desirable place on the entire island and was always fully booked.
So there is a place for solar PV, but not really for a grid connection unless your avoided cost of utility power is about 30 cents/kw/hr, and you can bank any surplus (or get paid) and assuming no subsidies from the utility. And are nearish the equatorial regions. Much of the third world worth being a tourist in has electricity rates north of 25-30 cents USD, so solar PV is starting to look very viable especially if you want back up redundancy as the hotel I stayed did. I also have 800 watts of solar panels on my RV trailer too, and they are great when off the grid and want some peace and quiet from the generator. But the grid connected solar build out north of 40 degree latitude doesn’t make sense when you factor no production for winter.
The “solar road” results are in, and predictably, they suck.
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Yes, and how they SUCK.
Thx for reminding!
“The panels are also likely to be covered by dirt and dust, and would need far thicker glass than conventional panels to withstand the weight of traffic, which will further limit the light they absorb.”
Thick glass is one thing; they have very thick glasses in money exchanges, and you see through it very well.
But road-glass, glass on which you can drive, that’s a completely different product.
And my intuitive guess is that the first power modelling that was promoted was for flat panels at that latitude, possibly with thick glass, but without the road-glass.
I live in northern Alberta, we have chained up snow plows that cruise the highways at 50 mph, pushing snow off, and spreading sand and salt. Even the asphalt does not survive some winters…
Salted water on electric wiring, when the snow melts and the sun comes back, should be funny.
Well, since greenies don’t agree with animal testing, here’s where they can prove their committment.
“Here Emily, hold this while we test to see if this will electrocute any bunnies”.
Working in round numbers over a cup of coffee, half the land surface (sunny side) of earth is about 75 x 10^12 m2. Solar puts out 200 watt/m2. One concludes that if we were to cover the entire land surface with solar panels (leaving no room for terrestrial life), we could produce about 150 x 10^14 watts with solar. World energy consumption is estimated to be 1.575×10^17 watt-hour. Solar is not a serious player, unless you could put solar panels in orbit or on the moon free from atmospheric attenuation and get it down to Earth somehow. Earthbound solar is a waste of time and money, a novelty application at best.
Most of my home energy use is for heating and cooling. A geothermal heat pump would be the best way to lower that cost (By an estimated 80%). For commercial scale we need to see a demonstration of hot dry geothermal. Only this and nuclear (lwr, msr, fission-fusion hybrid, thorium, whatever) have the potential to replace natural gas and coal for the generation of electricity. Even without the CO2 scare it would be best to conserve natural gas and coal for future use as feedstock for materials rather than for energy consumption. Unfortunately as this article points out, solar and wind are not (and will not) make a dent.
The results from NASA’s preoccupation with solar energy to power missions instead of Radioisotope Thermoelectric Generator results are ‘in’ … and they suck
https://www.cnet.com/news/nasa-spots-still-silent-opportunity-rover-on-mars/
Wouldn’t these roads be dangerously slippery to drive on? What a weird concept to begin with.