The NextBase project, involving 8 research institutions and 6 companies, deals with the development of innovative, high-performance c-Si solar cells and modules based on the interdigitated back-contacted silicon heterojunction (IBC-SHJ) solar cell concept. Using this technology, cells with efficiency above 26.0% and corresponding solar modules with efficiency above 22.0% are targeted. In particular, a number of new design and process innovations throughout the wafer, cell and module fabrication that go beyond the state-of-the-art wil be introduced into the device to achieve the targeted efficiency values. At the same time, the NextBase project pursues the development of new, industrial and low-cost processes for the IBC-SHJ solar cells enabling a competitive IBC-SHJ solar module cost of <0.35 €/Wp.