Chinese researchers have developed a new type of tandem solar cell that achieves a power conversion efficiency of 29.71 percent. The solar cell uses a perovskite layer on top and a CIGS (copper, indium, gallium, and selenium) solar cell underneath. By splitting the sunlight between two materials, tandem solar cells can generate more electricity than conventional single-layer solar cells, reports PV Magazine. The tandem solar cell consists of a semi-transparent perovskite top cell and a CIGS bottom cell. After 2,000 hours of continuous operation, the tandem solar cells retained more than 91 percent of their original efficiency, demonstrating strong long-term stability.