To make solar power more efficient, researchers are looking to nature for inspiration. Scientists at the University of California, Los Angeles (UCLA) developed a bio-mimicking material that bends to gather more sunlight, just as sunflowers and other plants do.
Many plants naturally turn toward the sun, a phenomenon called phototropism. In densely packed areas, sunflowers even turn or lean in to zigzag patterns to maximize the sunlight they take in. In a study by crop eco-physiologist Antonio Hall found that sunflowers allowed to track the sun yielded 25-50% more seeds than ones wired and forced to remain vertical.
Considering how this natural sun-tracking technique improves plant growth, researchers wanted to apply these principles to solar panel technology. Assistant professor of materials science and engineering at UCLA Ximin He and her colleagues used stimuli-responsive material to mimic phototropism. They developed a micro-sized material less than one millimeter in diameter, which expands and contracts when exposed to heat to move it toward the stimulus.
With the material, the team then created a system called the ‘sunflower-like biomimetic omnidirectional tracker’ or SunBOT. According to New Scientist, each SunBOT is made with a stem of the light-reacting material with a “flower” on top is made of a light-absorbing material commonly used in solar cells. Each SunBOT is less than 1 millimeter wide.
The system turns as the stem material heats and cools. When exposed to light, the stem material heats and shrinks so it bends. When the flower moves into the the light, a shadow is cast upon the stem, which then cools, and stops shrinking and moving.
SunBOT has the potential to gather up to 400% more solar energy gathering over traditional, nonmoving photovoltaic materials of the same size, according to researchers.
According to Popular Mechanics, using thermal solar over photovoltaic technology could make these sunflowers a promising installation where traditional panels are ineffective, too large or where energy storage is not a large concern.