Graphene solar panels can generate electricity when it rains

August 12, 2020 | 3min read

Solar panels generate less electricity on rainy days than they do on sunny days. But that could change in the future thanks to graphene. Chinese researchers are working on a new kind of solar cell that can generate electricity rain or shine. Graphene is a wonder material that is being studied for many different uses. It is unique in that a graphene sheet is composed of a single layer of carbon atoms. That makes graphene the only known two-dimensional substance on Earth.

Dye-sensitized solar cells

Researchers from two Chinese universities used dye-sensitized solar cells to develop the new all-weather solar cell. Dye-sensitized solar cells are a low-cost alternative to current technology. These cells simulate the photosynthesis process used by plants by absorbing sunlight. These cells can be made to be flexible, they on backpacks and clothing to power small devices such as phone chargers. 

Dye-sensitized solar cells work well in low light conditions including under indoor light and on cloudy days. That makes them an ideal platform for an all-weather solar cell. They also work well at wider angles to the sun than conventional solar panels. All of these advantages make dye-sensitized solar cells an emerging technology that can be used to integrate solar power into more devices than ever before.

How rain can generate electricity

To enable the dye-sensitized solar cells to generate electricity when it rains, a thin layer of graphene is added to the top of the cell. Graphene has unique electrical properties. It readily conducts electricity and has excess electrons that can move with a little encouragement. It’s that property that researchers zeroed in on to create an all-weather solar cell.

Rainwater isn’t pure water. It contains dissolved mineral salts. These salts are composed of both positively charged particles and negatively charged particles called ions. When you dissolve any salt in water the positively charged and negatively charged particles that the salt is made to chemically dissociate. When that happens, water molecules slightly separate the positively charged ions in the salt from the negatively charged ions.

To generate electricity, the positively charged ions, including calcium sodium, and ammonium, contact the graphene surface of the solar cell. The negatively charged ions from the salt permeate the layer of graphene, enriching it with electrons. The difference between the positively charged water on the surface of the cell and the negative charge of the graphene layer then produces the potential needed for electrical current to flow. This double layer of electrical charges produced by the rainwater is called a pseudocapacitor. Capacitors are electrical components that store electrical energy. In this case, electrical energy is derived by splitting the positively charged ions in rainwater from the negatively charged ions.

Graphene could power a bright future

Graphene’s unique electrical properties have been shown to have promise in batteries, solar cells, and supercapacitors. Its unique electrical properties could be a real game-changer in the field of renewable energy. Solar panels, batteries, and supercapacitors made of graphene are lightweight, flexible, and cheap to manufacture. Graphene could be the super-material that powers the technology of the 21st century.

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