This document corresponds to the appendix of the paper Regionalisation in high share renewable energy system modelling by Schnidrig et al. in redaction, and is based on the Master thesis of Amara Slaymaker 2021, giving additional information about the methodology, data used and assumptions made. This Appendix is structured in three parts. First the methodological details of the energy system model EnergyScope are given, followed by (ii) the clustering method details with data source sand results and (iii) additional results and validation of the model.