The document discusses market design options for hosting high levels of variable renewable energy sources. It examines principles such as incentivizing renewable investments, ensuring security of supply by supporting flexible resources, and maintaining competitiveness. Three potential market design evolutions are outlined: 1) integrating renewables into existing markets, 2) better rewarding flexibility, and 3) potentially introducing capacity remuneration mechanisms. Case studies of recent reforms in Germany and the UK are then summarized, noting both countries' efforts to integrate renewables while supporting necessary flexible resources. Criticisms of the UK approach question whether it truly reforms markets or adds unnecessary complexity.