Switzerland is considering implementing a strategic energy reserve, a novel policy instrument that remunerates power plant operators for storing a minimum amount of energy in reservoirs to convert into electricity when called upon. The policy is envisioned for the winter period, when the country’s large hydropower reservoirs tend to be nearly depleted. This study analyzes the impact of such a strategic energy reserve on security of supply, consumer costs, international trade, and sustainability. A hybrid simulation model is developed that combines agent-based modeling and system dynamics. The simulations show that the reserve can improve short-term security of supply but does not improve long-term security of supply as it does not impact domestic investments or reduce the import dependency in winter. The reserve leads to a slight increase in consumer costs, even when including the reduction in outage costs. A larger reserve is more effective at reducing the supply risk but is proportionally costly. Lastly, we find that the policy induces scarcity periods that would not have occurred otherwise, which means that the reserve should have a high strike price to ensure it is only called upon as a last resort. We conclude that there is no structural need for a strategic energy reserve, as it only increases short-term security of supply and does not contribute to solving the structural problem. Any implementation should be done on an ad hoc basis, conditional on a short-term generation adequacy assessment. This has the potential to minimize the associated costs while maximizing the benefits.