One huge drawback of going solar is the fact that it only makes sense in areas which get abundant sunshine year-round. However, a team of scientists from China has now come up with a new solar cell, which can harvest energy even when itâ€™s raining.
This solar cell is made using graphene, which has proven to be a very promising material for use in the production of solar cells in the past. One of these properties of graphene is its conductivity, which is such that it allows electrons to flow freely across its surface. So when this material is put into an aqueous solution, the so-called Lewis acid-base reaction occurs, namely that pairs of positively charged ions bind with the materialâ€™s negatively charged electrons. Studying this property of graphene, the team developed a solar cell, which can generate power from raindrops.
Raindrops are comprised of various salts, which have positively and negatively charged ions. So when rainwater hits graphene the positive ions bind with the negative ions on its surface. Where the rainwater and graphene come into contact, they form a double-layer of electrons and positively-charged ions, which creates a so-called pseudocapacitor. The two layers thus have a difference in potential, which is sufficient to generate a voltage and current.
The scientists have produced a prototype dye-sensitized solar cell and applied a thin film of graphene to it. They tested this cell in a lab, using salty water made to closely resemble rain. The cell they tested successfully generated hundreds of microvolts and had the solar to electricity conversion efficiency of 6.5 percent. Their next step will be to further refine the cell, and they are confident that they will succeed in creating a market-ready all-weather solar cell soon.