Sunflowers Inspire a New Way of Increasing Solar Energy Yield
One basic method of increasing solar energy yield during the day is by finding the angle where the solar panels would meet the most energy dense point of the sun during the day. There is also the option to use solar trackers, mechanical devices that are connected to GPS and other monitoring systems that make sure that the panel is facing directly at the sun.
A new clever idea however, tries to look back at how nature solves this solar yield problem. Plants too, regularly require sunlight to grow, and what better inspiration could there be for our scientists and researchers, than the sunflower, a plant that passively moves in order to efficiently “catch” sunlight.
The sunflower solar panel concept was first conceived by Professor Hongrui Jiang, while tinkering with some of the new space-age materials of the 21st century. The challenge, as may have already hinted, was to create a solar tracking system for a panel that would not require active motion. This means that it should be able to change positions without the need to draw a single watt of power from any energy source.
The idea of imitating sunflowers to catch sunlight is of course not new. The existence of solar trackers clearly proves this. However, we may want to remind ourselves that plants aren’t really active living organisms, and most often their movements are often the product of passive processes (uncontrolled by any central nervous system) in their systems. The sunflower for example, uses a process called heliotropism, where the cells in a segment below the flower flex using potassium ions in order to adjust to the position of the sun in the sky.
In the sunflower solar panel setup of Professor Jiang, the equivalent of the sunflower’s flexible segment is a composite liquid crystalline elastomer (LCE) that is “laced” with carbon nanotubes. LCE has phase and size changing properties when subjected to heat, while carbon nanotubes hold the ability to absorb a wide range of different light wavelengths. When combined with a mirror that is installed underneath the solar panel, the LCE/carbon nanotube actuators adjust its size according to the light absorbed. The shrinking actuators would then make the solar panel bow down to face the source of the light. As the sun moves from east to west, some actuators will expand (as it cools down) and some would shrink (as it heats up), continually re-adjusting to let the panel face the sun directly for the entire day. The entire process is of course done passively, without the use of any other external source of energy.
According to the results of the tests made by Professor Jiang, they were able to increase the efficiency of the panels by a whole 10%. The net increase was quite impressive, considering that most internal material changes in solar panel design for the past few years have only made a few percentage increases in efficiencies so far.
The next challenge of their research is to make “sunflower” solar trackers that can be installed on larger panels. If the development is successful, it might be possible for us to see whole solar farms with solar panels that automatically adjust to the direction of sunlight, just like how their natural counterpart does it effortlessly.
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