Most of the bad press solar panels get has to do with their limited efficiency in bad weather. Sure, they might be great in New Mexico, but you wouldn’t use them as much in England. Well, a new innovation might soon change that.
Chinese scientists have developed a way for solar panels to produce electricity using rain water. They coated the bottom side of the solar cell with a thin layer of graphene, which interacts with the positively charged ions found in rain drops. On rainy days, the solar cells can be reversed with the graphene pointing upwards.
“Although great achievements have been made since the discovery of various solar cells, there is still a remaining problem that the currently known solar cells can only be excited by sunlight on sunny days,” wrote the researchers in a paper published in the journal Angewandte Chemie.
The breakthrough was possible thanks to a simple chemical process: the Lewis acid-base interaction. Rain is an excellent reservoir of dissolved salts full of positive and negative ions. When rain drops hit the graphene layer it forms a pseudo-capacitor and positive ions like ammonium, calcium and sodium stimulate electrical currents.
An atom-thick layer of graphene can generate hundreds of millivolts worth of voltage, and on sunny days, the same cells have an efficiency of up to 6.53 percent efficiency under simulated sunlight. The new design could be applied to many different solar cell designs and the researchers believe it “can guide the design of advanced all-weather solar cells.”
Solar cells are seen as the lowest impact energy alternative to fossil fuels. Their efficiency has improved dramatically over the last few years (well beyond 20 percent) with more and more countries, and private citizens, switching from non-renewable resources to harnessing the power of sunlight.