The purpose of this paper is twofold. Firstly, it wants to present a concise overview of the benelits to be expected from the development of a thin-film crystalline Si solar cell technology on a low-cost substrate as well as the technical and physical challenges encountered. It will become clear that a large number of options are open on the level of substrate, deposition technology and solar cell technology. Secondly, the focus will be on the approach chosen by the thin-film crystalline Si solar cell team of IMEC and the results and progress of understanding achieved by the group over the last five years. Basically, their technical strategy is based on an evolutionary scheme for the cell design. More specifically, a transition is made from a classical two-side contacted cell design to a one-side contacted cell type which paves the way for a monolithic module design. For the technical realisation of the thin crystalline Si layers, Chemical Vapour Deposition is expected to be the preferred technique, at least in a short and midterm perspective.