Photovoltaic plus energy storage model

Declining photovoltaic (PV) and energy storage costs could enable “PV plus storage” systems to provide dispatchable energy and reliable capacity. This study explores the technical and economic performance of utility-scale PV plus storage systems. Co-Located? AC = alternating current, DC = direct current.

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. Much of NREL's current energy storage research is informing solar-plus-storage analysis.

With more than 45 GW of utility-scale PV projects in the pipeline at the beginning of 2021, the US is on track to grow total utility-scale PV capacity to over 100 GW by 2024. Here we will examine the coupling of energy storage with PV by comparing three principle methods: AC-coupled, DC-coupled, and Reverse DC-coupledconfigurations.

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.

This reduces interconnection hassle. Also, it helps with maximizing the value of generated solar power Since solar plus storage system are spread out through the site due to siting needs, the converter connection design in simpler and repeatable. Solar plus storage system allows the owner to capture multiple revenue stream.

DC-coupled system (right figure)—with shared 50-MW inverter—must shift storage output to lower-price periods to accommodate PV output. DC-coupled system value decreases by about 1% relative to independent PV + storage system. Impacts of DC tightly coupled storage systems are more significant.