Abstract Fabrication of solar cells with very high efficiencies currently requires extremely complex processing. In order to make photovoltaics an economical large scale source of energy, very high efficiencies have to be achieved by low-cost processing. The innovative approach for the cost-effective production of highly efficient silicon solar cells presented in this paper is characterised by only four simple and environmentally safe large-area fabrication steps. The basic processing sequence consists of: (i) mechanical surface grooving, (ii) simple diffusion or inversion, (iii) shallow angle metal evaporation, and (iv) plasma silicon nitride deposition. Cell design, fabrication techniques and processing sequences for metal-insulator-semiconductor contacted diffused n+-p junction (MIS-n+p) and MIS-inversion-layer (MIS-IL) silicon solar cells are outlined. The new simple approach turned out to be most successful, as demonstrated by mechanically grooved MIS-n+p silicon solar cells with efficiencies above 21% using exclusively aluminium as metallisation.