European researchers set out to dramatically reduce costs of the central solar system component, the solar module, while increasing efficiency, enhancing sustainability and broadening the potential market. In particular, the ‘Crystalline silicon PV: Low-cost, highly efficient and reliable modules’ (Crystal CLEAR) project was designed to develop technology allowing a reduction in the use of expensive materials while simultaneously introducing more cost-effective ones, an increase in electricity output of the solar modules and automated low-cost mass production processes – all with a focus on enhanced sustainability. Crystalline silicon photovoltaic (PV) cells were the first type of PV cells to be widely commercialised, some of which are made from an ingot of melted and recrystallised silicon saw-cut into wafers. However, silicon is in short supply and cost is rapidly increasing. A strong competitor to the silicon wafer technology is production of thin film PV modules by depositing PV material on a ceramic substrate. Crystal CLEAR focused on producing crystalline silicon thin-film solar cells comparable with state-of-the-art wafer technologies (so-called ‘wafer equivalent’) at significantly lower cost and using an alternative feedstock, currently the silicon from which PV cells are made. Investigators developed the epitaxial wafer equivalent (EpiWE) and appropriate processing techniques to produce a full-size PV demonstrator module, the Superslice I. Life-Cycle Assessment (LCA) revealed a decrease in energy payback time of 1.8 to 2.4 years for Central Europe as well as a reduction in environmental impact of at least 18–24 %. The Crystal CLEAR project has the potential to enable Europe to regain PV market share lost to Japan in recent years, boosting the European economy with job creation and revenues. Reducing costs and increasing efficiency while improving the environmental profile of solar PV cells should strengthen the position of solar energy as an alternative to conventional electricity and enhance its more widespread application.