Powerhouse Road

Photovoltaics on traffic routes have what it takes to turn streets into power plants. In doing so, you develop renewable energies and at the same time preserve the landscape. Yet this form of energy generation is still in its infancy.

Foto: Shutterstock - Sky Vectors

Experts conduct research on the inductive charging of electric cars on solar roads while driving.  Photo: Shutterstock – Sky Vectors

Roads like Route 66 in the USA have become mythical symbols of mobility. On the traffic route around the corner we simply get from A to B. But soon our routes could turn into powerhouses. Innovative companies around the globe are looking to convert roads, paths, and parking lots into places that serve as energy supply points. Special solar modules embedded in the road surface are just as much a way of realizing the idea as solar power stations that run along the highway or parking lots covered with solar modules. The culmination of all these developments would be the inductive charging of electric cars on solar roads while driving. Research on this is already underway.

The ideas are coming at the right time. Resistance to wind turbines and large ground-mounted photovoltaic systems is increasingly forming among local residents. New, less conflict-prone ideas are therefore needed if the ambitious energy goals are to be achieved. Germany, for example, wants to generate 65 percent of its electricity from renewable energy sources by 2030, and by 2050 the figure should be as high as 80 percent. That would be almost double to 2019.

The integration of photovoltaic systems into existing infrastructure could dampen conflicts over solar projects, as hardly any additional space is needed. Currently, the technically possible energy generation potential of photovoltaic systems installed on, in, or above traffic routes is estimated at 72 gigawatts in Germany alone. By way of comparison, the Isar 2 nuclear power plant, which will be taken off the grid in 2022, has a rated output of almost 1.5 gigawatts and can supply 3.5 million four-person households with electricity each year.

First projects launched

However, the road to expansion of traffic route photovoltaics is long. Similar to France, the Netherlands, or Luxembourg, there are smaller, successful projects in Germany – such as the 15 meter long solar path on the site of the Westerholt coal mine in Gelsenkirchen or the 234 meter long noise barriers equipped with photovoltaic systems in Neuötting, Bavaria. They supply 51,500 kilowatt hours of electricity per year, which is equivalent to the annual electricity consumption of around 13 four-person households. Dr. Martin Heinrich, who is responsible for traffic route photovoltaics at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, is nevertheless confident about the future: “In addition to successful pilot projects, we’re also noticing a high level of interest from the public and politicians.”

Of the 72 gigawatts that traffic route photovoltaics could currently generate in Germany in purely technical terms, the 58 gigawatt majority would be generated on roads. “From an economic point of view, the integration of photovoltaics into the surface of squares as well as foot- and cycle paths is most interesting because the technical requirements for that type of surfacing are lower than for that on highways, but the connectivity for generated power is better,” explains the photovoltaics specialist. Heinrich also sees great potential in noise barriers along busy roads such as highways: “There are many different and worthwhile installation options, especially for bifacial modules, i.e. modules that generate electricity from both sides by means of solar radiation.”

Photo: Fraunhofer-ISE

The most economically interesting is the integration of photovoltaics into the covering of squares as well as walking and cycling paths. Photo: Fraunhofer-ISE

Photovoltaic systems on highways

Projects in Europe, Asia, and the USA attest that transport route photovoltaics could have a great future. Princeton University in New Jersey, for example, is realizing a project in which a parking lot the size of four soccer fields is covered with solar cells. Meanwhile, Fraunhofer ISE will be working with Austrian partners on a functional photovoltaic roof for highways in the coming years. In the Netherlands, the A37 highway in the province of Drenthe will be equipped with solar panels along 40 kilometers of median strip as well as to the right and left of the route. Once the solar power plant is commissioned, it could supply 35,000 households with electricity.

The exciting idea that electric cars could one day draw their electricity from the road surface by induction is still a pipe dream. “So far, there’s no experience whatsoever with photovoltaics, and the question of economic viability cannot yet be answered,” says graduate physicist Heinrich.

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