Significance

For solar water splitting to be an economically viable resource, a 10% or higher solar-to-fuel conversion efficiency is required. Silicon photovoltaics (PV) are particularly attractive because silicon absorbs most of the solar spectrum, is nonprecious, and PV devices have dropped in price dramatically within the last decade. We demonstrate that by coupling a buried-junction silicon PV module with water-splitting catalysts, a 10% solar-to-fuels efficiency is achieved using all nonprecious and technology-ready materials.