High Capacity Factor CSP-PV Hybrid Systems

Abstract

Tower concentrating systems with direct molten salt heat transfer and storage can deploy particularly inexpensive and scalable thermal storage, enabling cost-effective 24-hour generation using only solar energy. While typical capacity factors (CFs) for intermittent renewables are generally between 20% and 40%, the SolarReserve Crescent Dunes project will offer above 50%. This paper discusses how SolarReserve's CSP technology can cost-effectively produce a CF over 80%, and when hybridized with PV, can raise the CF further to roughly 90%. A detailed operational model of a hybrid system in Chile's Atacama Desert was produced, using localized data on weather and interconnection capacity, to illustrate this capability. Analysis of high CF CSP-PV hybrids leads to three important conclusions. First, it was found that effective configuration of high CF systems supported selection of fixed-tilt PV at a high angle, which is optimized for winter generation in order to minimize seasonal differences. Second, when a dispatch strategy was developed which incorporated multiple priority levels and which dispatched CSP in response to PV output, it enabled higher CF CSP-PV hybrid operations than the CSP accomplished alone. Third, it was found that average annual DNI was not a sufficient metric of solar resource, and that seasonal variability and consolidation of non-optimal days were also important to high CF designs. New metrics for solar resource measurement are proposed and discussed.