Graphene solar panels could generate electricity from raindrops

Scientists in China are producing solar panels that can produce energy from the last source you’d expect — rainwater.

In a study published in the journal Angewandte Chemie, researchers in China introduced a new type of solar panel that adds a layer of graphene, or carbon atoms arranged in a honeycomb structure, to dye-sensitized solar cells. A flexible layer of indium tin oxide and plastic is included underneath.

Graphene has unusual properties that allow electrons to move freely throughout the entire layer. According to the researchers, rainwater contains positively charged ions like ammonium, calcium and sodium. When water binds to the panel’s surface, a double-layer of positive ions and negatively charged electrons is created, which ends up producing a voltage and current.

Tests of the new solar panels have been able to produce hundreds of microvolts, which is small even compared to a standard AA battery, reports Quartz. The solar-to-electric energy conversion stood at about 7 percent, which is much lower than the 20 percent energy conversion achieved by the best solar panels on the market.

So there’s a long way to go before the new solar panels become more widely used. But more efficient future versions could mean big things for the solar industry.