Alternative Energy

Published on September 17th, 2012 | by Guest Contributor


New Passive Solar Tracker Mimics Sunflower

Sunflowers naturally follow the trajectory of the sun throughout the day, each leaf maximizing the amount of sunlight it receives. This evolutionary adaption is called heliotropism, and is what inspired professor Hongrui Jiang at University of Wisonsin-Madison to find more efficient ways to harvest solar energy.

In an amazing example of life imitating nature, scientists are using nature’s sun trackers, sunflowers, as models for solar energy inspiration.

Sunflowers are suntrackers

Sunflowers are sun trackers

Creating Passive Solar Trackers

Most of today’s solar trackers are “active”, meaning that they are reliant on electrical motors to position the photovoltaic equipment for better performance. A passive solar tracker, does not need an extra input of electricity to function, instead it uses the natural insolation energy (sunlight) to do the work.

Jiang’s Solar Tracker

Jiang’s passive solar tracker design is based on a combination of liquid crystalline elastomers (LCE), materials that contract in the presence of heat, and carbon nanotubes, which absorb light. “Carbon nanotubes have a very wide range of absorption, visible light all the way to infrared,” says Jiang. “That is something we can take advantage of, since it is possible to use sunlight to drive it directly.”

Boosting Traditional Solar Cells by 10%

With the combination of these two materials, a system that is capable of moving solar cells in the direction of the sun as a direct response of sunlight can be made. This is exactly what Jiang has done, and according to his tests, the new tracking system can boost performance rates of traditional solar cells with about 10% – twice the increase of what is common through material improvements in the solar cells themselves.

Would You Like to Learn More About Solar Trackers?

To see a prototype of the tracker in action, check out Jiang`s video called Artificial heliotropism in action.

Sources: Direct Sun-Driven Artificial Heliotropism for Solar Energy Harvesting Based on a Photo-Thermomechanical Liquid-Crystal Elastomer Nanocomposite

{sunflower image via Redmond Ramone}

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