In February 2016, France’s minister of Ecology and Energy announced that the country will pave around 1000 kms of road with solar panels over the next five years.
Solar powered pavements for vehicles are something that still sounds too far in the future to become a reality. The vision of smart highways that generate free energy, with interactive applications that can assist drivers, or simply improving safety conditions seems like a futuristic movie scenario.
Is this a real alternative today?
We have some real examples that encourage us to think that it is a question of time that technologies will be attractive enough to be considered as a good investment, let’s check some:
Solar Road (Netherlands)
The solar bike path in Krommenie, a village northwest of Amsterdam in the Netherlands, is considered the first solar road built that actually generates more power than expected.
The project was inaugurated in November 2014, and was designed by a consortium of organizations.
The 3.5M Euro project generated 9800 kWh of electricity in one year, feeding the general grid for public purposes.
The technology used here consists of concrete modules of 2.5 by 3.5 meters with a translucent top layer of tempered glass, which is about 1 cm thick. Inside, the PV installation is based on standard silicon solar cells.
Several maintenance issues created certain public reluctance about the project and the investment.
Solar Roadways (USA)
Two entrepreneurs from the US started this project in 2016 from scratch and today their website is a reference on the Internet when you search on this technology.
Thanks to several grants and donations, the group created a prototype of solar pavement for a parking lot. Not many technical specifications and cost have transcended, creating reasonable doubts about the project, especially about the investment and installation complexity.
The hexagonal-shaped tempered glass has a fritted top layer that allows cars to get proper traction. The solar cells are placed inside the modules, together with sensors, LEDs and the necessary circuitry to make them interactive for multiple applications. There is also a heating system to melt the ice during the winter.
Solar Roadways recently announced a commission to create a walking area at Sandpoint, Idaho (US), to be executed this coming summer.
The Wattway (France)
This French collaboration project between the road-building company Colas and the National Institute of Solar Energy seems to be the most serious attempt to brake with the controversy around solar powered pavements implemented in a big scale.
The technique here has been simplified in terms of installation method: now the PV surface will be attached on top of the existing pavement. With this way, the solar component acts as a second skin for the asphalt, reducing costs during installation and maintenance.
The panels are made out of a thin polycrystalline silicon film and coated in a layer of resin to strengthen them and make them less slippery.
After the announcement mentioned at the beginning of this article, it looks like France is betting seriously on this technology.
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These are three projects that bring us some conclusions of the pros and cons of solar pavements today. The technology is real, and has been tested by using different technical solutions.
If we attend to the challenges, there are many: accumulation of dirt in the surface; non-optimal exposure angle; complex installation procedures; reliability of the technology in a medium-long term; grid connection costs; environmental impact; strict safety requirements… and, most important here, the high cost.
The required investment for this technology, even for small-scale projects, shows a negative balance. Only with a strong R&D support, the technology will be improved at all levels, overcoming all these difficulties.
It is a question of perspective: years ago nobody would imagine to see airplanes powered by solar… Why don’t envision solar powered roads in the coming future?
Article by Nacho Zamora