  In the process of decarbonization, the global energy mix is shifting from
fossil fuels to renewables. To study decarbonization pathways, large-scale
energy system models are utilized. These models require accurate data on
renewable generation to develop their full potential. Using different data can
lead to conflicting results and policy advice. In this work, we compare several
datasets that are commonly used to study the transition towards highly
renewable European power system. We find significant differences between these
datasets and cost-difference of about 10% result in the different energy mix.
We conclude that much more attention must be paid to the large uncertainties of
the input data.
