Solar panel roads a dumb idea: Who knew?

A road to nowhere? Credit: Robert B.D. Brice/Wattway

Phys.org reports on the results from solar panel roads.  Shock, horror – it appears to be a stupid idea. Quote.

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% 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?

One of the first solar roads to be installed is in Tourouvre-au-Perche, France. This has a maximum power output of 420 kWs, covers 2,800 m² and costed €5m to install. This implies a cost of €11,905 (£10,624) per installed kW.

While the road is supposed to generate 800 kilowatt hours per day (kWh/day), some recently released data indicates a yield closer to 409 kWh/day, or 150,000 kWh/yr. For an idea of how much this is, the average UK home uses around 10 kWh/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%.

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 300,000 kWs and a capacity factor of 14%. And at a cost of €360m (£321m), or €1,200 (£1,070) per installed kW, one-tenth the cost of our solar roadway, it generates three times more power. End of quote.

Ah, but that was Europe – in America, it will be better … Quote.

In America, a company called Solar Roadways has developed a smart highway with solar panels, including sensors and LED lights to display traffic warnings about any upcoming hazards, such as a deer. It also has heating pads to melt snow in winter.

Several of their SR3 panels have been installed in a small section of pavement in Sandypoint, Idaho. This is 13.9 m² in area, with an installed capacity of 1.529 KWs. The installation cost is given as $48,734 (about £37,482), which implies a cost per installed kW of €27,500 (£24,542), more than 20 times higher than the Cestas powerplant.

Solar Roadway’s own estimates are that the LED lights would consume 106 MWh per lane mile, with the panels generating 415 MWh – so more than 25% of the useful power is consumed by the LEDs. This would reduce performance even further. The heating plates are also quoted as drawing 2.28 MW per lane mile, so running them for just six days would cancel out any net gain from the solar panels.

And this is before we look at the actual data from the Sandypoint installation, which generated 52.397 kWhs in 6 months, or 104.8 kWhs over a year. From this we can estimate a capacity factor of just 0.782%, which is 20 times less efficient than the Cestas power plant.

That said, it should be pointed out that this panel is in a town square. If there is one thing we can conclude, it’s that a section of pavement surrounded by buildings in a snowy northern town is not the best place to locate a solar installation. However, perhaps there’s a bigger point – solar roads on city streets are just not a great idea. […] End of quote.

Knock me down with a feather and colour me surprised. Who would have thunk it?


Do you want:

  • Ad-free access?
  • Access to our very popular daily crossword?
  • Access to daily sudoku?
  • Access to Incite Politics magazine articles?
  • Access to podcasts?
  • Access to political polls?

Our subscribers’ financial support is the reason why we have been able to offer our latest service; Audio blogs. 

Click Here  to support us and watch the number of services grow.

In solidarity with the those in the world’s most despised demographic, WH has decided to ‘come out’ as an old white male. WH enjoys exercising the white-male privilege that Whaleoil provides for him by writing the occasional post challenging climate change consensus; looking at random tech issues that tweak his interest, as a bit of a tech nerd; or generally poking the borax at anyone in public life who goes on record revealing their stupidity. WH never excelled on the sports field because his coaches never allowed him to play in his preferred position on the right-wing. WH also enjoys his MG.

To read my previous articles click on my name in blue.

Listen to this post:
Voiced by Amazon Polly
Tagged:
48%