Science and Tech

We don’t know how to make efficient solar rails. Going back to the roofs seems like the solution

Germany has released a new solar bike lane, although not in the way that we were beginning to see in recent years. It is a pilot project in the city of Freiburg, developed in collaboration with the Fraunhofer Institute for Solar Energy Systems. The objective? Create a solar roof along 300 meters of bike path. There are two main intentions with this proposal.

Almost 300 meters of modules: along one of the main bike lanes in the German city of Freiburg, they have arranged 912 photovoltaic modules. A 287 kW facility, 300 meters long and integrated into the urban space. It is estimated that it can produce around 280 MWh per year, energy that will be used mainly in the laboratories and buildings of the Fraunhofer Institute.

What does one thing has to do with the other? Technically this is not a solar lane, but a regular bike lane, but covered by solar panels. The main interest with this project is, on the one hand, to begin to protect cyclists from the unforeseen weather, at the same time that solar energy is produced when the day is good.

With this proposal we want to put on the table that it is possible to cover important areas of the cities with solar panels (including areas open to traffic). It is especially relevant because this proposal breaks with the concept we had of solar lanes not too long ago: instead of covering the asphalt with inefficient modules, the lane itself has been covered with traditional modules.

It’s not the first time they think about it. Already in 2019 it was inaugurated the first solar rail in Germany. A 90-meter lane covered by 150 solar modules in the shape of a paving stone. The goal with this solar bike path was to be able to melt snow and ice (a common problem in the German winter), as well as being able to produce 80kW per square meter to the local electricity grid.

Solar highways remain promising, but also raise many questions

Efficiency was a big challenge. This idea is not new either. SolaRoad already commissioned the first solar lane in the Netherlands in 2015. Photovoltaic cells integrated into concrete modules with a double layer of tempered glass to protect them. An area of ​​just under 70 meters that cost close to three million euros.

The problem With this type of solar rails, it fell on efficiency: they were capable of generating only 30% of the energy that would be produced with conventional solutions. In the case of the first lane of SolaRoad, the almost 100 meters of its route could only power 2/3 average homes per year.

Applying it to roads was not a good idea either. If these types of solutions can be applied to bike lanes, they could also be applied to roads. In 2019 we talked about the great failure of the first solar road experiment in France. The energy generation forecasts were not met, the cost of the first section was five million euros, and the panels had unexpected wear not only due to the movement of vehicles, but also due to objects that landed on the road (leaves that rot, etc.).

The first solar highway in the United States was also a disaster. Almost 6 million dollars of investment and 25 of the 30 solar panels broken in the first week of its installation. The case of the first Chinese solar road is also curious, in which a section of almost two meters was stolen at its opening.

Image | Badenova

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