Using two novel techniques, researchers at the National Institute of Standards and Technology (NIST) have for the first time examined, with nanometer-scale precision, the variations in chemical composition and defects of widely used solar cells. The new techniques, which investigated a common type of solar cell made of the semiconductor material cadmium telluride, promise to aid scientists in better understanding the microscopic structure of solar cells and may ultimately suggest ways to boost the efficiency at which they convert sunlight to electricity.