Several years ago, a seemingly interesting innovation was introduced to combat climate change and improve the economic condition of European countries. It was about replacing asphalt on parts of highways with special solar panels. Since then, enough time has passed and there are the first results of preliminary studies.
So, solar panels equipped under the road have a number of disadvantages. Firstly, the tilt angle is far from optimal, which allows for significantly less energy production. Also, the road may be subject to shading, which is a real problem, as shading only 5% of the surface can reduce electricity generation by 50%.
Most likely, PV modules will become covered with dust and dirt during operation. Additionally, the equipment must be covered with a thicker layer of glass to withstand large vehicles moving on the surface. It is also another contributor to the darkening of motorway sections.
With this arrangement, there is no air circulation, as, for example, when arranging structures on the roof. If there is no natural airflow, the batteries heat up more and for each degree Celsius about 0.5% of the total energy efficiency is lost.
As a result, there will be a significant decrease in the performance of the solar road in comparison with similar structures on the roof of the house.
One of the first roads was built in France. The maximum power output is 420 kW. This is 2800 m2 at a cost of 5 million €.
It was planned that the road would generate 800 kWh / day. However, the data obtained show that the real figure is 409 kWh / day or 150,000 kWh / year.
In comparison, the average residential building uses about 10 kWh / day. Accordingly, the power factor of a solar road, which measures the efficiency of a technology by dividing the average power output by its potential maximum power, is only 4%.
Similar studies were carried out in the United States for six months, where a low power factor was also obtained, in comparison with conventional solar power plants (by the way, see their prices on our website).
It is planned to try to cover some of the roads in the UK in the near future. These are relatively small sections of all motorways in the country. The total surface area is 2 billion m2. At first glance, this amount is huge, but if we consider that the area of buildings in urban areas is about 17.6 billion m2, it becomes clear that this is not so much. Interestingly, if solar panels were to cover all rooftops in the UK, they would bring significantly more energy than roads.
The tests carried out indicate that only small sections of the road are suitable for this technology, which will not significantly affect energy savings, but will only become an additional, niche source of energy supply.