OPTIMIZED PV + STORAGE SYSTEM DESIGNS FOR NODAL ELECTRICITY VALUE

摘要

Energy storage is an important mechanism for mitigating the decline in the energy and capacity value of solar photovoltaics(PV)at high PV penetrations.[1] Previous research has explored optimal PV + storage system designs as a function of storage duration,capacity,and cost [2],and as a function of the storage charging strategy(including solar-only charging or combined solar + grid charging)[3].Additional system design flexibility can be obtained by allowing the ratio of the direct-current(DC)PV module capacity to alternating-current(AC)inverter capacity to vary,taking advantage of low module costs to increase the AC capacity factor and allow simultaneous charging of storage and direct dispatch of AC power to the grid.A trend toward increasing PV/inverter ratios has been observed for utility-scale storage-free PV arrays installed in the U.S.[4],but the impact of inverter overloading on the revenue and optimal system design of hybrid PV + storage plants has yet to be rigorously explored.Here,we determine optimal dispatch strategies,PV/inverter ratios,and storage/inverter ratios for hybrid PV + storage systems at thousands of locational marginal pricing(LMP)nodes across the US over the years 2010-2018.We consider both the revenue from wholesale energy provision at the nodal LMP and capacity provision at the clearing price or average contract price for the Independent System Operator(ISO)for each node.We calculate the break-even cost of storage in order for storage to add net value(rather than cost)to hybrid systems,and observe changes in optimal system designs over time as solar penetration increases and LMP profiles evolve.