Over the past decade Switzerland has invested significantly in pumped storage plants (PSP). They aim to exploit arbitrage opportunities by pumping water from a lower reservoir to an upper reservoir to store electricity in the form of hydraulic potential energy when prices are low and generating when prices are high. The changing generation-mix in Switzerland threatens these arbitrage opportunities in the long-term. To study this, we develop a heuristic to endogenise PSP bidding decisions, and integrate it in [1]’s simulation model of the Swiss electricity market. Our results show that initially the increase of photovoltaic capacity encourages pumping, but the nuclear phase-out and the expiration of long-term import contracts significantly decrease the available energy, leading to a decline in pumping. Although those changes in the capacity-mix increase the difference between peak and off-peak prices significantly, PSP are unable to exploit these because of the low availability of cheap energy to pump. This situation severely limits arbitrage opportunities in the long-term. We conclude that large scale arbitrage requires the availability of cheap excess energy. This can be achieved either by demand management or by supporting base load technologies.