Swiss Electricity Supply and Demand in 2017 and 2050. Is the Swiss 2050 energy plan viable?

The Swiss energy plan 2050 includes an increase of electricity consumption by 37% from the electrification of transport and heating, together with phasing out 2.9 GWe of nuclear power (about one-third of the nation's gross electricity generation) and substituting this lost power mainly with solar PV. We examine to what extent this energy plan adds up in the spirit of the late David MacKay. We use the realised production of a recent year and develop and validate reconstructions of the Swiss grid in January and July 2017 with one-hour resolution and use these as a platform to simulate the Swiss grid in 2050, incorporating the main elements of the 2050 plan. We confirm that, in July 2050, when solar energy is abundant, Switzerland can be self-sufficient in electricity. Newly expanded pumped hydro storage may shift load from daytime solar peaks to nighttime deficit. Hydro and pumped hydro are displaced from current high value midday production to nighttime production when Swiss solar PV produces zero power. In January 2050, solar PV will produce negligible power leaving Switzerland starved of indigenous supply. There is no electricity surplus to charge storage that may therefore stand idle. We compute an import requirement equivalent to 69% of demand, or approximately 6.0 TWh just for January 2050. We quantify that surplus European wind power may meet this deficit for some of the time but during frequent pan-European lulls in the wind, it is not assured that Europe will have surplus power to export.