Semi-transparent solar cells that could be added to windows to efficiently harvest energy from indoor light as well as the sun have been developed by an international team led by UCL researchers.

The technology, described in a paper in Advanced Energy Materials, could help turn buildings into power generators at night and on cloudy days, as well as in sunshine.

The researchers engineered solar windows that let in 30% of sunlight—ordinary glass might let in 80% or 90%—while generating a record amount of energy from indoor light and efficiently harvesting energy from sunshine.