Solar panel road [image credit: Wattway]
For several obvious reasons cited below, the conclusion should be that solar panels on road surfaces perform extremely poorly and are essentially an irrelevant waste of money. If the money has to be spent, putting the same amount of panels somewhere more suitable would be an easy improvement to make.
H/T Phys.org
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, says Dylan Ryan at The Conversation.
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% of the surface of a panel can reduce power generation by 50%.
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.
Unable to benefit from air circulation, its inevitable these panels will heat up more than a rooftop solar panel too. For every 1°C over optimum temperature you lose 0.5% of energy efficiency.
As a result a significant drop in performance for a solar road, compared to rooftop solar panels, has to be expected. The question is by how much and what is the economic cost?
Continued here.
Tallbloke's Talkshop 
Fools and their money are soon parted.
These green scamsters were laughing all the way to the Cayman Islands.
Anyone with an internet screen can see this info free of charge…
In general photovoltaic solar panels should be mounted at an angle of 10 to 15 degrees plus the site’s latitude. Therefore in London, which has a latitude of around 51 degrees, solar panels should ideally be mounted at an angle of approximately 65 degrees.
In the Northern Hemisphere, solar panels should face to the South where the sun is found at midday. Similarly in the Southern Hemisphere, solar panels should face to the North.
http://www.reuk.co.uk/wordpress/solar/solar-panel-mounting-angle/
Not many roads with 65 degree tilts 😎
The photo is of Segolene Royal’s road in north west france (not far from chez Roger). One was also built in brussels. I saw one update report which was really derogatory but I cannot remember the figures.
I have not seen a report on Royal’s. It’s probably a complete failure and the left want to keep it quiet
oldbrew please don’t be so negative.
All that is needed is roads with a steeper grade/camber, and vehicles with the suspension adjusted to accommodate.
I’m sure, given the correct level of government financial incentives it could be fixed, Elon Musk probably has plans for such and idea ready to go and is just waiting for a little incentive to come his way.
FTFY:
“For several obvious reasons cited below, the conclusion should be that solar panels on road surfaces perform extremely poorly and are essentially an irrelevant waste of SOMEONE ELSE’S money.”
oldbrew, I suspect that there aren’t many roofs that meet those criteria either. I have seen solar panels on north facing roofs in the UK – anything for the installers to get the subsidies.
The other thing, even if you do manage to get a roof that faces south and is a the best slope angle they always forget that the panels need cleaning. Without cleaning the output drops off rather spectacularly.
Regular rainwater can be a cleaning agent for solar panels.
Solar Panels are designed to be self-cleaning in the UK, and as such would be deemed to have little to no maintenance at all.
https://www.jojusolar.co.uk/2015/09/01/cleaning-and-maintaining-your-solar-panels-an-expert-guide/
I personally want them to keep their solar roads dream alive. The loonier their ideas – the more they are discredited.
oldbrew, as an engineer that has seen a lot of solar panels out in rural France I call bullshit on the marketing hype in that ‘guide’ – it basically says ‘buy our expensive cleaning service’. The UK has birds, pigeons in the cities others in the country, and the effects of a large dollop of bird lime on a glass panel has to be seen to be believed – it also helps to collect the dust thrown up by cars. In the countryside the dust from farming is a lot worse, usually requiring the panels to be cleaned every few days.
Mark, while I agree with your sentiments there is a problem. They use our money to do so and I don’t approve of them wasting my money on their stupid plans.
For the most part solar panels in the UK seem to face the wrong way, ie south, producing maximum electricity at midday when demand drops. A maths professor at a Manchester university, Salford ? has calculated that if solar panels were oriented in a west south west direction then they would produce as much energy in total as they do when facing south, but would produce that energy at a more useful time when demand increases in the early evening.
It is surprising that power companies and the government haven’t taken this onboard and demanded that solar panels be re-orieinted. Government is of course congenitally stupid so their failure is perhaps to be expected.
J Martin – the bad news is that in the UK it’s dark in the early evening for several months of the year 😐
Not mentioned seems to be their performance as roads.
I’d be considerably worried that a glass surface was not very good for traction, especially when wet. Then what happens when you grit the road and run some wheels over it? Translucent is not transparent. Does grit work as well on glass? How well does it stand up to snow ploughs? And if you can’t plow, what do you do? Wait a few days for electric heat to melt 4 feet of snow? At -20 F?
What happens when a wreck happens? Spilled fuel, fires, sliding metal rims after the tire is peeled off? When, and it is a when, a wreck shoves metal into the power line in the panel, what volts will be conducted into the wreck? Will it stand up when an over weight truck makes a wrong turn onto it, or are you out a few hundred thousand € or £? How about really big fire trucks and water haulers?
Let’s just say I’d not want to lock up the brakes with a big truck behind me on a couple of inches of snow…
Let’s stick with the Spaghetti Factory in the median….
Oldbrew – a good point, but I assume the professor of mathematics took that into account. But if he didn’t then I can’t see that it matters a great deal as I doubt that solar panels in winter do a lot, even at midday.
JM – that’s correct, the angle of the winter sun is too low to be effective in many of the countries likely to have lots of solar panels (e.g. the majority of Europe and North America)…if it appears at all that is.