Metal halide perovskite semiconductors have emerged as excellent materials for light harvesting applications, with photovoltaic (PV) energy conversion efficiencies of lab-based cells increasing rapidly from 3.8% in 2009 to 26.7% today. Single and multijunction perovskite PV modules can exhibit a very small energy payback time of 0.09 years and a greenhouse gas emission factor as low as 13.4 g CO2 equivalent per kWh, which compare favourably to other technologies including market-leading silicon cells. Perovskite-based technologies can therefore play a key part in achieving society's decarbonisation goals.