Perovskite solar cells are rapidly catching up to their silicon forebears in terms of efficiency, but one area they continue to lag behind in is production speed. Now, researchers at Stanford University have developed a new method of making perovskite solar cells at up to 40 ft (12 m) per minute, which is even faster than silicon.

Silicon has dominated the solar cell market for decades, but in recent years it’s been at risk of having that crown snatched away. The fastest-rising newcomer is perovskite, which has gone from less than four percent efficiency in 2009 to over 20 percent earlier this year, closing in on silicon’s long-standing record of around 25 percent. It’s also potentially cheaper and more energy-efficient to manufacture.

But of course, perovskite isn’t perfect. It’s far less stable than silicon, so it's fiddly to produce in bulk and the process often introduces flaws that make the cells degrade faster in the elements. Now, the Stanford researchers claim to have developed a new way to manufacture stable pervoskite in useful amounts at practical speeds.

The team calls the new method rapid-spray plasma processing, which is performed using a robot with two nozzles – the first sprays a liquid mixture of perovskite precursors onto a sheet of glass, then the second nozzle blasts the liquid with plasma, which quickly converts it into a thin film of perovskite.

Using this method, the team says that the perovskite film can be produced at a rate of 40 ft per minute. It should be cheap too – the researchers estimate that the modules could be made for about US$0.25 per square foot (0.09 sq m), which is about one tenth the price of silicon.

“We achieved the highest throughput of any solar technology,” says Nick Rolston, co-author of the study. “You can imagine large panels of glass placed on rollers and continuously producing layers of perovskite at speeds never accomplished before.”

The final product also has a respectable efficiency of around 18 percent, and after five months of continuous use, the modules were still operating at 15.5 percent efficiency. While that’s not too bad for perovskite, the team says that the next major hurdle would be to find ways to make sure the cells last for a much more useful length of time.

“If we can build a perovskite module that lasts 30 years, we could bring down the cost of electricity below 2 cents per kilowatt-hour,” says Rolston. “At that price, we could use perovskites for utility-scale energy production. For example, a 100-megawatt solar farm.”

The research was published in the journal Joule, and the team demonstrates the rapid-spray plasma processing method in the video below.