Anti-Reflective Solar Panels Inspired by Butterfly Wings

Innovation: Academia

Anhui Polytechnic University

2020

Image: Boris Smokrovic / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Transform Radiant Energy (Light)

The sun is the ultimate source of energy for many living systems. The sun emits radiant energy, which is carried by light and other electromagnetic radiation as streams of photons. When radiant energy reaches a living system, two events can happen. The radiant energy can convert to heat, or living systems can convert it to chemical energy. The latter conversion is not simple, but is a multi-step process starting when living systems such as algae, some bacteria, and plants capture photons. For example, a potato plant captures photons then converts the light energy into chemical energy through photosynthesis, storing the chemical energy underground as carbohydrates. The carbohydrates in turn feed other living systems.

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Modify Light/Color

Color in living systems comes from pigments and the interaction of light with surfaces. Color serves many purposes for living systems, such as attracting prey or mates, providing warnings, or protecting through camouflage. To create the effects needed for each purpose, living systems must control the expression or visibility of pigments and the interactions (such as reflectance and refraction) of light. To do so, they have strategies that modify color or light to increase or decrease the color’s position, intensity, opacity, and more. Male hummingbirds, for example, have brightly colored feather patches on their throats; the coloring comes from pigments, structures that refract light, or a combination of the two. When a male hummingbird hovers near a potential mate, it modifies the angle of these feathers to create a bright, colorful display. However, when it needs to mute the colors to reduce conspicuousness, such as to avoid a predator, it modifies the angle again.

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Solar panels from Anhui Polytechnic University have patterned nanostructures that reduce light reflection.

Benefits

Increased efficiency
Reduced light reflection

Applications

Commercial and industrial energy generation

UN Sustainable Development Goals Addressed

Goal 7: Affordable & Clean Energy

The Challenge

Light reflection is a common problem that occurs in many applications. For example, any light that is reflected off solar panels reduces the total amount of energy that can be used, which decreases efficiency. Additionally, when particles such as dust adhere to a surface, they block potential light from entering, further reducing efficiency.

Innovation Details

Butterfly wings appear black not because of , but because they are able to absorb light and reflect almost none of it back using specialized structures. Researchers mimicked these structures and placed them silicon-based solar panels, to help reduce light reflection. If less light is reflected, that means more of it can be absorbed, increasing the overall efficiency of the panels. Researchers found that these structures decreased light reflection from more than 35% down to less than 5%. As a result, the short-circuit current (the largest current that can be obtained from the photovoltaic cell), was increased by 66%.

Biological Model

Butterfly wings appear black not because of pigment, but because they are able to absorb light and reflect almost none of it back. This is achieved by a mesh-like surface of ridges and holes on the scales of the butterfly wing, which channel light into the scale’s interior. There, pillar-like beams of tissue scatter light until it is almost completely absorbed.

See Related Strategy

Biological Strategy

Butterflies Hack Light Waves to Produce Brilliant Color

Morpho butterfly

Wings of morpho butterflies create color by causing light waves to diffract and interfere.

References

Journal article

Antireflective design of Si-based photovoltaics via biomimicking structures on black butterfly scales

Solar Energy

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