Research project on the A81 motorway: solar roof above the motorway
A solar roof for the highway – at least for a small part of it. This is what is to be built at the Hegau-Ost rest area on the A81 motorway in Baden-Württemberg in southern Germany. The project is part of a joint research on road construction in the three neighboring countries of Germany, Austria and Switzerland.
The Fraunhofer Institute for Solar Energy Systems (Germany), Forster FF Verkehrstechnik and the Austrian Institute of Technology (both in Austria) designed a structure to cover the highway with photovoltaic modules. This prototype will now be used to demonstrate that solar power generation above fluid traffic works in reality. The prototype consists of a roof measuring 10 meters by 17 meters made up of photovoltaic modules located approximately 5.50 meters above the roadway resting on a steel structure.
“With this research project, we want to develop the potential of the motorway for the production of renewable energy,” said Steffen Bilger, Parliamentary State Secretary at the Federal Ministry of Transport and Digital Infrastructure. “Covering a motorway is particularly difficult technically because of the fast traffic below. But the vision of reusing an already sealed surface to generate the energy needed by the electric vehicles driving underneath is something that simply must be pursued.
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Building PV modules on roads is much more expensive than PV on existing roofs or in open spaces. For example, in the event of an accident on the road below, the support structure must be protected against a possible impact of the vehicle to avoid a collapse. To make matters worse, from a length of 80 m, these support structures should be classified in the same way as tunnels and the structure would then have to meet even higher safety requirements.
Limited fields of application
The aim of the German-Austrian-Swiss research project is therefore to demonstrate that such a structure is economically feasible under real traffic conditions and can be operated permanently. Although the modular design of the prototype has some cost advantages, widespread application of solar roofs on highways is rather unlikely in the medium term. In comparison, there is still great potential in areas where renewable energy can be produced at lower cost. But for special and locally limited areas of application, experts see the possible uses of a solar roof on highways.
Construction of the prototype is expected to begin in the fall. After that, the operation of the system will be scientifically monitored for about a year. Further pilot applications can then be deployed based on this experience.
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