It has been shown that a long term sustainable energy system based on a high penetration of solar photovoltaics requires massive deployment of day charging electric vehicles to make use of the excess solar electricity generation at sun peak hours. In this paper the synergy between these technologies is further explored, determining the minimum penetration levels that allow fulfilling the climate and energy targets. Simulations for a case study of Portugal in 2050 using an electric vehicles smart charging approach show that a 100% renewable energy based electricity supply is possible with certain photovoltaics and electric vehicles combinations and that the environmental targets to reduce carbon dioxide emissions are just reachable with significant electric vehicles market share. The notion that vehicle charging will have to take place during working hours to maximize petroleum displacement is reinforced. (C) 2015 Elsevier Ltd. All rights reserved.