This paper explores the application of Pumped-Storage Hydroelectricity (PSH) within an electricity market characterised by a substantial share of renewable and intermittent electricity production. The purpose of PSH is to enhance the alignment of supply with demand by storing energy at electricity surplus and releasing it during shortage. The Juktan Power Station, once the largest PSH facility in Sweden with a storage capacity of about 25 GWh and a maximum generation of 335 MW, serves as a case study. An in-depth analysis of the properties of the Swedish electricity market and its influencing factors is conducted. Wind speed data is successfully used to increase the accuracy of electricity price prediction. Furthermore, a model is developed to calculate potential profitability employing various operation methods. In conclusion, large-scale PSH provides significant benefits to the robustness of the electricity system, with a clear increase in value beginning in 2021. However, concerns about grid tariff design, electricity market development and energy storage incentives mean that investments are not obviously profitable.