With the pressure on to save ourselves from global warming, we need more efficient solar panels like yesterday. But the next best thing is soon, and thanks to new developments in solar technology, solar panels may increase their efficiency by almost half by 2025.
Still, that will only be about 35% efficient. Much of the sunlight that hits a solar panel can’t be turned into electricity. Right now, the average solar panel is about 22% efficient at turning sunlight into usable energy. Only the most high-end panels — the really expensive ones used for spacecrafts and such — are more efficient.
Silicon-based solar panels are finicky. They prefer shorter wavelengths in the red and yellow part of the electromagnetic spectrum. Longer light waves are too weak, and light waves in the blue and green end of the spectrum tend to bounce off the silicon panels. Worse, they can generate heat that degrades the panels.
In 2014, a group of researchers at the University of Cambridge started trying to convert blue and green light waves into red ones so that solar panels could harness more power. The team, led by physicist Akshay Rao, hoped to boost efficiency to 35%. The University of Cambridge ran with the idea, using it to start a new company, Cambridge Photon Technology, with Rao as its scientific officer.
“We’re trying to deal with this problem of how you improve solar PV performance and bring down costs significantly without throwing away the established silicon technology,” said David Wilson, head of business development at Cambridge Photon Technology, as reported by Nature.
Of course, this is a complicated process. But put very simply, when light strikes photovoltaic material, it creates something called an exciton. This consists of an electron (negatively charged) and an electron vacancy (positively charged) connected by an electrostatic charge. But with the right material, an organic polymer semiconductor, the photon can split into two excitons with lower energy. Both of these can convert to electric current. “You’re preserving the total energy that comes in and out, but you’re making the silicon receive a higher photon flux in the portion of the spectrum that it’s good at converting into electricity,” Wilson said.
By the end of this year, Rao hopes to have a working prototype that is 31% efficient. Watch for the 35% efficient panel sometime after 2025.
Lead image © Nature