Smart solar device lights underground work and living spaces

Researchers have developed a device that can harvest daylight and relay it to underground spaces, reducing the energy cost of lighting them up

Spotted: After dark is not the only time light is needed. As we have recently highlighted, there are large-scale plans in the works to build underground work and living spaces. Moving some buildings underground can help save energy, free up space for nature and allow building in polluted areas. Now, a team at Nanyang Technological University, Singapore, has designed a smart device that can harvest daylight and relay it to underground spaces, reducing the energy cost of lighting them up. 

The team developed a device that sits above ground. It includes an acrylic ball, a plastic optical fibre cable, light sensors and computer-assisted motors. The ball acts as a magnifying glass, bringing the sunlight into sharp focus. This focused light is collected at one end of the fibre cable and transported to light fixtures underground, where the light is emitted through the other end of the fibre.

In order to optimise the amount of sunlight received by the device, the small motors automatically adjust the position of the fibre’s collecting end as the sun moves. The device was developed by Assistant Professor Yoo Seongwoo from the School of Electrical and Electronics Engineering and Dr Charu Goel, Principal Research Fellow at NTU’s The Photonics Institute. It is compact enough to be mounted on a light post and can be made with off-the-shelf materials.

According to Assistant Professor Seongwoo, “Our innovation [is] potentially very easy to fabricate at scale. Due to space constraints in densely populated cities, we have intentionally designed the daylight harvesting system to be lightweight and compact. This would make it convenient for our device to be incorporated into existing infrastructure in the urban environment.”

Efficient use of solar energy is a vital component of creating more sustainable buildings and cities. Technology like that developed at NTU joins other lighting and energy innovations, including a film that converts light to clean energy and an LED art installation that helps plants grow.

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