The Deliverable presents different network models aiming to properly represent both the transmission and distribution grids and tries to answer the impact on the operation of the system of integrating PtG and the impact of PtG on the electricity grid development. In particular, the study regarding the transmission network is organized by considering three network samples. The first network is the European configuration of the CIGRE’ HV Transmission System. The second transmission network considered is the simplified version of the European 400kV system, covering most of continental Europe (17 countries). The third transmission network considered is a simplified EU network, composed of 256 nodes: it represents the results obtained by clustering the EU transmission network (composed of more than 6000 nodes), and uses standard values for the HV lines.