For solar-plus-storage—the pairing of solar photovoltaic (PV) and energy storage technologies—NREL researchers study and quantify the unique economic and grid benefits reaped by distributed and utility-scale systems. Energy storage has become an increasingly common component of utility-scale solar energy systems in the United States. Much of NREL's analysis for this market segment focuses on the grid impacts of solar-plus-storage systems, though costs and benefits are also frequently considered. Why do we need. This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www. Ramasamy, Vignesh, Jarett Zuboy, Michael Woodhouse, Eric O'Shaughnessy, David Feldman, Jal Desai, Andy Walker, Robert Margolis, and Paul Basore. The grid must continually adjust its output to maintain the grid power balance, and replacing the grid power output by adding a battery energy storage.