It took silicon-based solar panel technology 30 years to reach an efficiency of 21%. At the end of 2015, a new kind of solar material hit that milestone in a research lab in just three years, making it the fastest improving solar technology to date.
If the material, a crystalline mineral made of calcium and titanium called perovskite, works out as researchers hope, it could one day provide an alternative to today’s silicon-based solar panels that is at once cheaper, more efficient, and lightweight.
The material was first explored in the 1990s as a transistor and LED material. It wasn’t until 2009 that scientists began testing perovskites for solar-energy applications, and 2012, when a grad student at the University of Oxford made a breakthrough to improve its efficiency. What has followed since is a flood of research from all over the world: “The race is on to capitalize on this potential and start manufacturing modules,” reads a University of Oxford case study.
Perovskite-based solar cells have some key advantages, says Sam Stranks, a researcher who was part of the early University of Oxford research group and is now a joint fellow at MIT and the University of Cambridge and a TED Fellow. The mineral is abundant, and unlike silicon panels, perovskite panels wouldn’t require much energy to manufacture, just some gentle heating on a printing press-like device. Rolls of the material could be thin, flexible, and lightweight, and could even be printed on building glass. Stranks estimates that a perovskite solar cell could ultimately cost less than half of its silicon counterparts.
In 2013, Oxford’s Henry Snaith spun out a company called Oxford PV to commercialize the technology. According to Stranks, who collaborates on academic research with the startup but isn’t formally on the team, they hope to bring the first products on the market by early next year.
Early perovskite applications will be a companion to silicon-based solar, not a replacement. Oxford PV is working with existing solar manufacturers to debut a panel with a perovskite layer printed on top of existing panel technology, boosting its efficiency by about 20%. Silicon panels generate power today at about 70 cents per watt, and this layer would bring it to at least 60 cents per watt, says Stranks, and it would require little change to existing manufacturing.
It will be a much longer before perovskites can stand alone, which will require a number of further innovations, including making larger cells and making sure they can operate reliably for many years. Moisture is very bad for the material, so Stranks says that durable encapsulation structures will be needed to keep all humidity out. “We still have work to do, and it will take a global push to realize the full potential,” he says.
But the future of solar using perovskite panels could look very different. They can be tuned to be different colors and could line glass buildings someday. Because the material is flexible and lightweight, it could help deploy solar to more remote communities. And the material could ultimately work out for LED lights, too (LEDs are essentially solar cells run in reverse).
“Traditionally LEDS are quite fixed in their color spectrum so it’s very hard to recreate the nice white light we get with regular bulbs,” says Stranks. With perovskites, he says, “you can change the color temperature by just changing the perovskites you add in, and make a really nice white light.”