Technology development needs for integrated grid-connected PV systems and electric energy storage

Researchers at Sandia National Laboratories and the U.S. Department of Energy´s Solar Energy Technologies Program assessed status and needs related to optimizing the integration of electrical energy storage and grid-connected photovoltaic (PV) systems. At high levels of PV penetration on our electric grid, reliable and economical distributed energy storage will eliminate the need for backup utility generation capacity to offset the intermittent nature of PV generation. This paper summarizes the status of various storage technologies in the context of PV system integration, addressing applications, benefits, costs, and technology limitations. It then discusses further research and development needs, with an emphasis on new models, systems analysis tools, and even business models for high penetration of PV-storage systems on a national scale.