Nature Reviews Physics, Published online: 27 May 2026; doi:10.1038/s42254-026-00938-5 Transparent conducting electrodes are a key performance and sustainability bottleneck in high-efficiency perovskite–silicon tandem solar cells. This Review examines how optical, electrical and interfacial losses in transparent conducting electrodes arise in tandem cells and outlines strategies to enable scalable, low-indium electrodes for next-generation devices.