World first: a 400-metre long five-metre high motorway noise barrier incorporating 1,600 square metres of solar cells that convert sunlight into electricity on both sides. This gives the barrier a second function: besides blocking noise, it also generates energy. TNO realised this innovation on behalf of and in cooperation with Rijkswaterstaat. Heijmans Infra constructed the solar noise barrier.

This is the 'Solar Highways' pilot project along the A50 near Uden. The special thing about the structure is the fact that the solar cells are actually integrated in the noise barrier and have not been added to it. The vertical position also makes it possible not only to block the noise well, but also to capture a lot of light on both sides and thus generate electricity. Because the solar cells absorb light energy on both sides, optimum yields no longer depend on having a south-facing installation. The amount of energy generated is virtually independent of the direction in which the motorway runs. Optimum use is always made of both morning and afternoon sun.

Optimum combination

For a long time, it has been technically possible to install solar cells in noise barriers, but the cost of doing so is high while efficiency is relatively low. TNO has now succeeded in devising and building a structure that optimally combines the functions of blocking noise and generating energy. For Rijkswaterstaat, this is about achieving sustainability ambitions as well as about organisational innovation; it is thinking of leasing the installation, which is already connected to the national electricity grid, to a cooperative of local residents who are very interested in this option.

Cooperation with industry

Solar Highways is an example of successful cooperation in the quadrilateral of government, knowledge institutions, industry and, perhaps soon, a social organisation. TNO developed the prototype of the solar panels in the barrier, connecting research with practice in the process. Long-term cooperation with our innovative manufacturing industry has resulted in a method for capturing sunlight on the back of solar cells and converting it into electricity. In combination with vertical placement, this provides a range of new possibilities. In addition to noise barriers, solar panels and crops or vegetation come to mind, because in this position they hardly take up any space and keep other activities possible.

Necessary energy mix

It is expected that the noise barrier will be able to supply around fifty households with green electricity. The trial, which will last one and a half years, will examine the technical, organisational and financial feasibility of the structure. For TNO, this development fits in with the mix that is necessary to make the energy transition a success. This involves using as much of the existing surface area as possible, such as roofs, facades, roads and also noise barriers.

This work has been partially financed by the EU in the framework of the LIFE+ program.

For more information about Solar Highways go to the website

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