Many countries have targeted a gradual transition towards 100% green generation; however, there is uncertainty concerning the economic and social consequences of such a transition. The main technologies that have been implemented are hydro, wind and solar. The latter two could cause an increase in electricity prices due to a mismatch between demand and supply. This paper uses a system dynamics approach to analyze the transition process of Switzerland, which is gradually moving from nuclear towards solar and hydro base generation. We consider hydro-pumped storage to address the timing problem between supply and demand. We developed different scenarios to test the viability of such a system. Our findings indicate that leaving the system to a free market will entail shortages during the transition, as well as a doubling of the electricity price. To mitigate this effect, we propose a capacity auction mechanism to smooth the transition process. We find that subsidizing PV indirectly encourages storage, thereby eliminating shortages, and mitigating the increase in the electricity price during the transition.