Splitting light makes solar cells more efficient

SciDev.net : An inexpensive plastic device that concentrates and separates light into its constituent wavelengths can make solar panels more efficient. The spectral light can be focused and targeted toward solar cells that are optimized for that wavelength. “The new device is a combination between a prism, which separates the different wavelengths of sunlight, and a lens, which concentrates the light that can be used to help harness a greater amount of energy from the sun,” says Carlo Maragliano, the lead author of the research, which was published in the Journal of Optics . Traditional broad-spectrum silicon solar cells can convert short visible wavelengths (blue and green light) at only 18% efficiency, but with cells optimized for those wavelengths the efficiency can be increased to 40%. Stacking the optimized cells compacts the amount of space needed to match and exceed the efficiency of standard silicon cells. Abu Dhabi, which funded the research, hopes to generate 7% of its electricity from solar power by 2020. However, the technique hasn’t yet been tested in dusty conditions, and the plastic can warp under prolonged exposure to sunlight.