Solar power plants could everywhere if two things were to fall precipitously: the cost of making solar cells and the price to install them. The first is actually falling fast (about 6% annually since 1998), but remains higher than equivalent fossil fuel energy in most places. The second is also distressingly high for those who want to see solar power rout coal and gas in today’s energy markets. So to make solar boosters’ dream come true, tomorrow’s solar panels must be printed on cheap, durable materials that can be installed anywhere sunlight is bound to strike them.
New research from around the world is driving us ever closer to that goal, says Silvija Gradecak, a materials science and engineering professor at MIT. And her lab, among others, is now releasing the bendy, peel-and-stick solar panels to prove it.
"There was a significant effort to develop these type of devices [in the last few years], and the slope of this improvement is very high," says Gradecak. "In just a couple of years, power conversion efficiency [of new flexible solar cells] has gone from less than 0.1 percent to 5% to 7%. And it’s just a couple of years of work. We’re learning the basic principles … and we have a clear path to improve them even further."
Gradecak, like others, is focusing on a new class of solar panels—organic, thin-film cells—made from abundant and robust materials that can be manufactured on the cheap (compared to conventional silicon counterparts). Gradecak’s lab recently created its own version of a transparent photovoltaic cell by using flexible graphene and a nanowire coating. Publishing in the journal Nano Letters, the team showed in its proof-of-concept, half-inch-sized devices could be light, flexible, and transparent at a lower cost than comparable cells—if their assumptions hold up at scale.
Researchers at Stanford are also in pursuit of their own next generation solar cell: a flexible, peel-off solar panel that can stick to almost any surface. Publishing in Scientific Reports this past December, Xiaolin Zheng, a Stanford assistant professor of mechanical engineering and the paper’s senior author, showed how a flexible, robust solar cell could adhere to paper, plastic, window glass, without losing any efficiency—a problem typical of new PV materials. The research team deposited a 300-nanometer film of nickel on a silicon/silicon dioxide wafer, sandwiched it between a second nickel layer and then applied a protective polymer. After heating and submerging it in water, new cells could simply be peeled off.
Scientists have been pursuing the principles that lead to cheap, reliable power from the sun since Albert Einstein won a Nobel Prize for describing the photovoltaic effect in 1921. We’ve made remarkable progress, but we’re still in the dark about exactly how to turn today’s solar panels into something so cheap, robust, and effective they can become a ubiquitous source of power across the globe.
That prize, however, may finally be in sight. "I personally believe this is not just theoretical," says Gradecak. "In a couple of years you will see these types of devices commercially."
Hat tip: Dmass