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Photovoltaic Roofing for Motorways

Development of a concept and deployment of a demonstrator for the generation of solar energy in the road infrastructure

Energy conversion through photovoltaics (PV) is one of the key technologies for increasing the share of renewable energy sources in primary energy production. However, the use of this technology on a large scale requires adequate installation areas for the PV modules. While such areas are potentially available within the high-level road network, they have hitherto only been considered for photovoltaic energy generation to a very limited extent.

Although the technical feasibility of PV installations in the road network has been demonstrated in the context of several projects in Austria, Germany and Switzerland, the use of PV is currently often focused on the energy supply of nearby consumers, for example, rest areas and tunnel lighting. However, a solar panel installation in the form of a roof over traffic areas potentially has other positive implications in addition to energy generation: These include the protection of the road surface from precipitation and overheating, a subsequently increased service life of the pavement and additional noise protection that may be achieved through appropriate construction.

Investigation of the added value and practical suitability of a PV-roofing

Within the framework of the project cluster "PV-SÜD" led by AIT, consisting of the projects Photovoltaic Road Roofing Concept (PV-SÜD-K) and Photovoltaic Road Roofing Demonstrator (PV-SÜD-D), the focus is now on two research questions: On the one hand, it evaluates whether a PV roofing offers the hoped-for added value for road administrations in addition to energy generation, such as protection of the road surface. On the other hand, the consortium investigates whether this form of integration of solar panels into the road infrastructure is practical and compatible with existing operational and maintenance procedures.

Together with the project partners Fraunhofer Institute for Solar Energy Systems ISE and Forster Industrietechnik GmbH, the first phase of the project consists of the development of a concept for a prototype roofing. This will involve developing an appropriate PV concept including suitable modules and a compatible supporting structure that meets all safety requirements. In the second phase of the project this prototype will be built as a demonstrator, equipped with measurement technology and scientifically monitored during its one year operation. This will enable researchers to investigate how such a structure can meet the diverse requirements of the high-level road network with respect to drainage, wind and snow loads, stability and impact resistance, maintenance procedures and traffic safety. The reliability and durability of the PV elements and the supporting structure, their structural suitability and efficiency are also key topics of the research work.

Focused AIT competence in a multidisciplinary consortium

AIT is responsible for the overall coordination of the pilot project and provides expertise from a wide range of research areas. With the Competence Unit Photovoltaic Systems of the AIT Center for Energy and Fraunhofer Institute for Solar Energy Systems, two leading research institutes in the field of photovoltaics in Austria and Germany are involved in "PV-SÜD". This ensures that both the current state of the art and research in the field of photovoltaics as well as the experience of both institutes in implementing innovative concepts will be incorporated into the project.

The analysis of effects beyond solar energy production is a major "PV-SÜD" project objective. Thus, the Competence Unit Transportation Infrastructure Technologies of the AIT Center for Low-Emission Transport provides its experience in analysing road surfaces, noise barriers, bridges or retaining walls as well as traffic safety at the service of the project. The Center for Low-Emission Transport is also responsible for the overall coordination of "PV-SÜD". Forster International, represented in this project by Forster Industrietechnik, contributes extensive experience in the field of traffic engineering and steel construction as well as civil engineering planning, implementation and assembly of structures alongside and above roads and is represented in this field in both Austria and Germany.

According to project manager Manfred Haider from the AIT Center for Low-Emission Transport, "The PV roofing is intended to achieve the following objectives: (1) energy generation through photovoltaics using suitable PV module technology, (2) flexible use in the high-level road network, (3) increased durability and preservation of the surface properties of the road through protection against overheating and precipitation, and (4) additional noise protection. These requirements will be evaluated with regard to technical and economic feasibility and verified in a demonstrator. From the analyses of the concept phase as well as the measured data of the demonstrator we hope to gain valuable insights for the future application of such photovoltaic systems in the D-A-CH region".