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In less than 24 hours, the world’s deserts receive more energy from the sun than humans use in one year, making solar-driven power one of the most attractive and reliable alternatives to burning fossil fuels. Despite its enormous potential for generating long-term sustainable energy, however, solar technology comes up short due to its inefficiency in rainy and overcast weather.
While enormous solar fields in the Moroccan Sahara promise to power entire portions of Africa and Europe, could the same technology be applied to less accommodating climates?
A team of Chinese scientists has invented an all-weather solar cell that can harness energy from raindrops, making it the first solar technology capable of functioning at full efficiency rain or shine. They published their findings in the international edition of German chemistry journal Angewandte Chemie.
“Although great achievements have been made since the discovery of various solar cells,” wrote the researchers, “there is still a remaining problem that the currently known solar cells can only be excited by sunlight on sunny days.”
In the new design, the researchers integrated two complementary structural components, each capable of yielding electricity under the influence of a different type of weather. The first, an electron-enriched electrode, generates electricity on rainy days, while a dye-sensitized solar cell completes photoelectric conversion on sunny days.
Raindrops are little pools that brim with dissolved salts, and are therefore full of positively and negatively charged ions. To harness these charges, the team lined the bottom of the solar panel in an atom-thin layer of graphene, a material that can absorb the positive ions from water. A series of simple chemical reactions that occur when the droplets strike the graphene surface then generates a current of electrons.
The new solar cell is capable of producing hundreds of microvolts of energy from rainwater, and has a solar-to-electric conversion of 6.53 percent efficiency. Solar efficiency refers to the amount of electricity conducted by a single panel based on its surface area. While 6.53 percent may not seem like much, the team hopes that this new concept will be adapted to further future designs for more advanced all-weather solar cells.