A team of scientists has recently developed “transparent photovoltaic” (TPV) devices—transparent versions of the traditional solar cell. Unlike the conventionally dark, opaque solar cells (which absorb visible light), TPVs make use of the “invisible” light that falls in the ultraviolet (UV) range. These transparent solar cells could take us towards a new era of personalised energy, integrated into windows, vehicles, cellphone screens, and other everyday products.