Renewable and conventional energy sources should compliment, not compete. Using the tools of systems engineering, synergistic energy systems can be designed, built, and operated. Design and operation optimization allow the system to take advantage of the flexibility that hybridization provides, so that precious energy resources are used efficiently. Advanced control techniques allow these systems to run reliably, despite ever-fluctuating supply (solar, wind) and demand. Using these tools, novel designs and operating strategies can be developed for all kinds of energy systems including: solar, wind, nuclear, fossil fuel, geothermal, and buildings. Smart design and operation mean that the whole can be greater than the sum of its parts.