This book presents currently available renewable energy technologies (RETs) and explores their possible integration into the economically viable and green residential microgrids of tomorrow. The emphasis is on the importance of RETs in today’s energy-efficient building designs, and on those RET mathematical models suitable for both performance simulation and economic appraisal. A range of energy storage alternatives, as well as typical energy consumption patterns, are also thoroughly described and precisely simulated. After selecting the right components for a hybrid system, readers are introduced to problems of system integration and optimization, using simulations that support alternative scenario exercises and comparative analysis. The multicriteria comparison also includes detailed investment appraisals, using both conventional methodologies and the authors’ novel green-accounting-based appraisal to investigate the impacts on the economic efficiency of the project.