In this practical guide, globally recognized renewable energy researcher and professor Henrik Lund describes the modeling and simulation techniques that can be utilised to ensure at the outset of any renewable energy project that the resources available will meet supply demands. A clear, comprehensive methodology is set forth for comparing different energy systems' abilities to integrate fluctuating and intermittent renewable energy sources. Dr. Lund offers a freely available accompanying software tool, EnergyPLAN, that automates and simplifies the calculations supporting such detailed comparative analysis.