3 MW CPV project in Golmud, China. Credit – Wikimedia Commons Chinese solar manufacturer Longi has certified a two-terminal tandem perovskite silicon solar cell prototype at 34.6 per cent efficiency, a figure that pushes past a theoretical ceiling long treated as a hard limit for single-junction silicon cells.According to PV Magazine, which reported the announcement directly, the company explained how the cell works. According to the U.S. Department of Energy, the 33.7 per cent figure refers to the Shockley-Queisser limit, the maximum theoretical efficiency a single-junction silicon solar cell can achieve.Longi's 34.6 percent result gets past that ceiling not by…