The most abundant energy source in the world is sunlight, but engineers have had trouble using it to generate clean electricity because the silicon in solar cells is so costly. In September, engineers at MIT announced a new strategy that could bring down the high cost of harvesting sunlight.
Using technology borrowed from lasers, they have developed a low-cost solar concentrator that collects sunlight from a large area and focuses it onto a much smaller area, boosting the efficiency of existing solar cells by 15 to 20 percent. The concentrator prototypes look like square, brightly dyed panes of glass. When sunlight hits the concentrator, dye molecules applied to the glass redirect most wavelengths to the edges of the glass, similar to the way a fiber-optic cable carries light. Solar cells mounted on the edges of the concentrator then capture the light and convert it to electricity. Any light that passes through the glass is picked up by another solar cell.
Marc Baldo, the electrical engineer who led the study, said that concentrators could be used to bolster solar cells almost anywhere the sun shines. “It looks quite practical for skylights,” he said, “or in big skyscrapers, because they’ve got the whole surface area covered in glass.”