SOLCHECK will significantly advance the understanding and quantification of the solar contribution to past, present, and future climate evolution in the Northern Hemisphere on decadal to centennial timescales. We will assess the role of natural solar variability for the observed and future global and regional climate change. Further, we will provide estimates of the potential impact of extreme solar scenarios, such as a Grand Solar Minimum and other extreme solar events, on climate evolution. A special focus will be the contribution of solar forcing to decadal climate variability and decadal climate prediction skill. The latter will be achieved by a combination of existing (CMIP6) model simulations and dedicated model experiments, including the operational German decadal climate prediction system MiKlip. We will also investigate the mechanisms how the solar signal in the middle atmosphere couples to the troposphere and the ocean as well as the relevant teleconnections involving internal variability modes of the atmosphere-ocean system. This will be realized using state-of-the-art chemistry climate models (CCMs) with computationally efficient atmospheric chemistry modules allowing for ensemble simulations. All models also include atmosphere-ocean feedbacks, a necessary prerequisite to investigate the role of the Sun for climate change. From this exceptional CCM ensemble we finally will be able to extract a statistically robust solar signal in climate.