How can programs motivate homeowners to make their homes energy-efficient before installing solar panels? And how can incentives support a whole-house retrofit approach that will optimize energy savings and prevent solar systems from being oversized? California, Wisconsin, New Jersey, and Austin Energy have been grappling with this challenge for years. Their experiences show well-designed incentives may drive the joint adoption of solar power and energy efficiency. Simply introducing energy efficiency requirements into the solar installation process may not be successful without adding financial motivation.