Rain means clouds and clouds mean less sunlight. That’s bad news for most solar cells, but a new design can actually make use of rain drops that fall on its surface, allowing it to generate electricity even when the weather’s bad.
The new solar cell has been developed by researchers in Qingdao, China. Unlike most solar cells, this device has a single sheet of graphene on its upper surface. The clever part is that rainwater isn’t pure: It contains compounds like ammonium, calcium and sodium, all of which become ions when they’re in solution.
When that water sits on top of a layer of graphene, it creates what the researchers call a ‘pseudocapacitor’—spots of unbalanced charge where electrons are donated from one side to the other. Unbalanced charge is basically just a voltage, which means that the researchers can use the process to capture electricity.
Sadly, we won’t be coating every solar cell in graphene just yet—and not only because of the expense. The solar cell created by the team is just 6.5 per cent efficient in optimal solar conditions, which compares pretty damn badly to the best solar cells, which are around 20 per cent efficient. Meanwhile, mere microvolts are generated by the raindrop capacitors.
Still, the idea’s a good one, as it would make solar power far more versatile in environments where the weather is a mixed bag. Now the researchers just need to make it work a little better.