The paper 'Challenges and Approaches to Electricity Grids Operations and Planning with Increased Amounts of Variable Renewable Generation: Emerging Lessons from Selected Operational Experiences and Desktop Studies' focuses on analyzing the impacts of variable renewable energy on the operation and planning of the the power system (mostly, generation system). It is aimed at informing stakeholders in power utilities, regulatory bodies and other relevant audiences, on the fundamentals of technical challenges and approaches to operate electricity grids with renewable energy. It covers renewable energy as a whole, but in particular, focusses on wind and solar energy. It also presents three case studies of countries, including China, Gemany and Spain.