Starting from the first solutions proposed in the middle of last century, roundabouts became worldwide popular as a tool to break down the statistics on car accidents, and Europe encourages and promotes this technology as a solution to the problems of urban and extra-urban traffic.
RAST (Round About Solar Tracking) proposes to use the space available in roundabouts, which are already equipped and monitored, to produce electricity with photovoltaic single-axis tracking systems. The main target is to harvest energy with an aesthetic and energy improvement of what today is called the third landscape.
The rotation system may be realized in two ways.
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The PV plant structure is supported by wheels rolling along circular cement rails.
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By building a shallow circular pool equipped with a floating platform of polyethylene tubes which forms the basis of the photovoltaic plant. In this case there is also a system of panel irrigation that provides cooling during the maximum solar radiation periods, and allows to create aesthetic fountain-shaped effects.
In both cases a pair of electric low power motors are used to perform the single-axis tracking with very low torque.
RAST allows the use of spaces which are already available and not used for other purposes. The roundabouts are in fact the subject of aesthetic improvement and gardening works which have considerable investment and maintenance costs. Furthermore the suggested solution is not a niche one as the use of land for infrastructure purposes is increasing and organic planning of these spaces will prevail in the near future.
The tracking system that we propose is flexible, innovative and patented. Compared to many already existing tracking systems (one or two axes), it has a much lower cost and greater robustness and reliability.
The system has a number of engineering and logistic advantages:
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It uses spaces otherwise lost or expensive to maintain
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It integrates with urban and extra-urban territory management policies
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It is very visible to the public and to surveillance, and therefore dramatically reduces insurance costs that are high for standard solar fields.
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There is almost always a connection to the network due to the presence of lighting systems or telecommunication antennas which do not preclude the installation of a photovoltaic system.
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It can provide a significant contribution to the national PV park. Infact, with proper planning and suitable intervention on 1000 large roundabouts and 1000 highway junctions, it is possible to raise the RAST park to 500 MW.
