Input data for SELARU modelling framework application in a case study to demonstrate the impact of spatially explicit representation for energy system optimization, particularly in depicting incremental grid expansion and its contribution to accumulation of economies of scale. The case study focuses on the electricity sector of Indonesia to represent a highly complex and geographically diverse energy system. SELARU modelling framework is applied using three spatial representations: single-node model, low resolution multi-node model and high resolution multi-node model. Detailed information about the spatial representations can be found in https://doi.org/10.31219/osf.io/aw4bd.