This thesis investigates the charging power and battery capacity needed for fast charging of fully electrical busses at end stations in Uppsala, Sweden. The operator, UL, wants to implement electrical busses by 2020 and a new depot for the city buses is being built with possibility to slow-charge the busses overnight. However, due to restrictions in the transmission grid the requested grid connection was denied by Vattenfall Eldistribution. Simulations in this thesis is based on the existing bus schedules for city bus route 6 and route 8 in Uppsala. The routes were selected by UL as suitable candidates for fast charging at end stations. Simulations were made with varying charging power, battery capacity and energy usage by the buses. A worst case-scenario was simulated to ensure that the solution would work even in bad weather conditions. The results show that it is possible to dimension the battery to match the current time schedule. The battery capacity needed depends on charging power, length of route and time available for charging. With 300 kW charging power, the battery capacity needed to manage the bus schedule during weekends were higher than during weekdays. Furthermore, the needed battery capacity for weekends on route 8 were significantly higher than for route 6. If the whole bus fleet would be electrified, the choice of charging technique and battery size depends on the routes and passenger capacity needed. A combination of different charging techniques may be the most efficient solutions when the whole bus fleet is considered.