The evolving energy and capacity values of utility-scale PV-plus-battery hybrid system architectures

In this study, we explored how the value of hybrid systems comprising solar photovoltaics (PV) and lithium-ion battery storage could evolve over time. Using a price-taker model with hourly energy and capacity prices projected to 2050, we simulated the revenue-maximizing dispatch of three PV-plus-battery architectures, with fixed component sizing, in three locations. The architectures reflect different coupling types, which vary in terms of whether the PV and battery systems have separate inverters or a shared inverter and whether the battery can charge from the grid. We found that the highest-value architecture today varies largely based on PV penetration and the magnitude and timing of peak-price periods. As PV penetration increases over time—based on the evolution of the bulk power system—two trends emerge that indicate a convergence of the values of the systems studied. First, the energy values of the three architectures converge as an increasing fraction of energy from the coupled PV is used to charge the battery. Second, their capacity values converge to that of the battery as the capacity credit of stand-alone PV approaches zero. Of the systems studied, no single architecture has the highest year-one benefit-cost ratio in every region and year, and benefit-cost ratios of PV-plus-battery systems range from a 15% reduction to a 25% increase compared to separate PV and battery systems. Understanding the factors that influence the performance and economics of PV-plus-battery systems will help system planners and researchers evaluate the potential benefits of these hybrid resources to future power systems.