French startup Colas raised eyebrows in the photovoltaic industry when it introduced its Wattway technology in 2016, due to mechanical problems with street solar modules. However, he now says IEC certification is a step closer to commercialization.
Solar industry experts are divided on the long-term viability of solar roads, even though they are very popular on social media. Some argue they are little more than gimmicks that actually damage solar's image as a scalable, accessible and mainstream energy source. Others, however, believe that if busy city arteries can start to "pay" with photovoltaics, the technology could reduce CO2 emissions and support the spread of electric vehicles.
In line with the second approach, the French startup Colas and the French National Institute for Solar Energy (INES) – a division of the French Commission for Alternative Energies and Atomic Energy (CEA) – have jointly built the first road world's photovoltaic cycle route in Normandy, France, in 2016.
Industry experts have raised serious concerns about the integrity of solar modules, attracting significant attention both in France and outside and sparking considerable skepticism. Solar panels installed on the ground can be subjected to considerable mechanical stress, which seriously compromises their performance. Furthermore, the integration of special technologies to reinforce module structures can significantly increase their costs compared to conventional ones.
Despite these concerns, the Netherlands quickly followed in France's footsteps, as land is scarce in the country. In 2016, a cycle path near Amsterdam was equipped with solar panels and another was built in 2020 in Utrecht. Then, in the United States,
SolarRoadways equipped a short sidewalk near Route 66 in Missouri with hexagonal solar panels embedded with multi-layer LED lights. Germany, on the other hand, implemented its first photovoltaic cycle path project only in 2023, in the city of Freiburg. However, the system consisted of an overhead photovoltaic shade.
After more than seven years of development, solar roads have not reached commercial feasibility and have remained at pilot project level. But Colas and CEA-INES say a new development could change things.
“The latest version of the Wattway flooring has just been certified to current IEC standards in the photovoltaic industry, like any standard solar panel – an exciting achievement and a world first for a walkable module,” they said in a recent joint press release.
Colas said its solar modules are now twice as large as those used in 2016. They now feature an unspecified type of resin on the front side. After a series of tests, Colas obtained IEC 61215 and IEC 61730 certifications for the panels.
“The IEC 61215 and 61730 test results were fully compliant, both in terms of performance stability and module safety,” the company said. “The electrical insulation resistances evaluated at the end of each test branch remained well above the required level.”
Colas and CEA-INES said the new certifications represent a step towards commercializing the technology, although they have not yet provided further technical details on the tests.
“These certifications demonstrate that the reliability of Wattway modules is similar to that of photovoltaic panels on the market,” they said. “This is a fundamental step in the development of the Wattway Plus offering for the production of renewable electricity for on-site self-consumption.”
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