© 2019 Elsevier Ltd The integration of variable generation challenges electricity systems globally. Using Ireland's electricity sector as a case study, we highlight multiple challenges in reconciling ambition for variable renewable integration with market economics and system operation. Ireland has the highest share of non-synchronous variable renewable electricity on a single synchronous power system. This case study examines the strategy being implemented to optimally balance between efficiency, flexibility and adequacy while maintaining a fully functional system that strives to adapt to evolving conditions. The transition that the Single Electricity Market underwent to comply with the EU Target Market was a major overhaul of what made the all-island market a success. Volume-based reliability options have distinct advantages over capacity payments. System services are critical for system stability and 14 separate system services are being developed. These actions, when taken together, provide an insight into the lengths to which this electricity market must go to transform from its cost-based nature to a value-based alternative that rewards flexible and reliable capacity with the ability to evolve with market conditions of the future.