A Dutch bike lane made up of solar panels has produced a disappointing amount of electricity for the second year in a row and is performing far worse than engineers had expected, broadcaster NOS said on Wednesday.

The cycle lane near Maartensdijk in Utrecht province was world news when it opened and heralded as the longest solar bike path in the world.

The path, made up of solar panels set into concrete, covers 350 metres and the aim is to show that solar panels do not have to be an eyesore or take up unnecessary amounts of space. 

When the cycle lane was opened, its designers said they hoped it would produce some 137 kWh of electricity per year. However, by July 2022, the figure was only 36 kWh, or 27% of the forecast, despite the sunny spring. This year production has dropped again, to 26%. 

Sustainable energy expert Thijs ten Brinck said on his website that the solar panels may be less efficient because they need to be smooth and placed at an angle to maximise their capacity. 

“Bike paths have to be flat and rough, to stop skidding. And that means a lot of dirt gets stuck and keeps the sunlight away,” he said. In addition, being cycled on may have let the solar panels deteriorate more quickly, he said. 

Nevertheless, the good news from the experiment is that the solar bike lane does work and there is no visible damage, he said. 

The trial is set to run to June next year and then Utrecht province will decide whether there should be a follow-up. 

An earlier Dutch experiment, in which solar panels were embedded in a road, ended early because of the damage caused by the heavy vehicles.