PV plus energy storage budget

Can a utility-scale PV plus storage system provide reliable capacity?

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.

Is energy storage a viable option for utility-scale solar energy 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.

How does a DC-coupled storage system affect PV output?

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.

Which PV system has the highest benefit/cost ratio?

In all cases the 30% ITC is applied to the PV portion of the system. Benefit/cost ratios are calculated by dividing annualized benefits by costs. The PV-only system has the highest benefit/cost ratio. These results follow historical trends that have resulted in very limited deployment of PV plus storage systems.

How does independent PV + storage increase value?

Increases value by about 1% relative to independent PV + storage. In other periods (July 1 shown here), storage plant cannot be fully utilized because of the operation of the PV system. Combined output of independent PV + storage plant (left figure) is as high as 70 MW, which is possible because of the separate inverters.

How many mw can a PV & storage plant produce?

Combined output of independent PV + storage plant (left figure) is as high as 70 MW, which is possible because of the separate inverters. DC-coupled system (right figure)—with shared 50-MW inverter—must shift storage output to lower-price periods to accommodate PV output.