The project "Solar contribution to climate change on decadal to centennial timescales" is one of eight projects funded by the German Ministry for Education and Research BMBF within the coordinated programm "Role of the Middle Atmosphere in Climate", ROMIC-II. The aim of SOLCHECK is to better understand and quantify the contribution of solar activity on the natural climate variability on decadal to centennial timescales. Our contribution is the investigation of extreme solar activity as well as the further development of the chemistry-climate model ICON-ART to consider the impact of solar variability by solar UV radiation and solar wind on stratospheric ozone, as well as dedicated model experiments with ICON-ART.