All-weather graphene solar panels will generate energy from rain

The performance of solar cells is often determined by the range of weather conditions. However a breakthrough by Chinese scientists has brought closer the practicality of solar cells being able to generate energy during… wait for it… both sunny and rainy days.

The aim was to develop a solar cell that would work efficiently under any weather conditions, said study lead author Qunwei Tang, of the Ocean University of China in Qingdao with the remarkable all-weather cells coated with graphene to make them effectively generate energy from rain.

From the abstract of the report published in the International Edition of Angewandte Chemie (warning: take a deep breath)

“A flexible solar cell is presented that is triggered by combining an electron-enriched graphene electrode with a dye-sensitized solar cell. The new solar cell can be excited by incident light on sunny days and raindrops on rainy days, yielding an optimal solar-to-electric conversion efficiency of 6.53 % under AM 1.5 irradiation and current over microamps as well as a voltage of hundreds of microvolts by simulated raindrops.”

Put simply, the important factor is that raindrops are not just water. They contain a range of salts that form positively and negatively-charged ions from such compounds as sodium, calcium and ammonium. The atom-thin graphene coating on the cells is placed on efficient cells that have been dye-sensitised. The graphene layer attracts the positively-charged ions in the rainwater.

According to the study, graphene “…is characterized by its unusual electronic properties: It conducts electricity and is rich in electrons that can move freely across the entire layer (delocalized).” This allows the atomic-scale form of carbon to bind positively-charged ions with electrons, said the report.

“Future solar cells may produce electricity in all weather,” Tang says as he and his team set the stage for future development of all-weather graphene solar cells. While still in development mode, the graphene-coated cells could bring the dream of all-weather solar cells generating energy from the rain as well as the sun just a little closer.