Improvements to heliostat cost, performance, and reliability are necessary to achieve the U.S. Department of Energy (DOE) 2030 SunShot target for CSP of $0.05/kWh with 12 hours of thermal energy storage (TES) in the Southwest (DOE SETO 2021b). Low-cost, highperformance Generation 3 (Gen3) CSP technologies are expected to integrate with hightemperature tower receivers and TES with advanced supercritical carbon dioxide (sCO2) cycles. DOE recently down-selected the solid-particle pathway as the most likely to meet the 2030

This report is available at no cost from the National Renewable Energy Laboratory at www.nrel.gov/publications. Task 2: Enhancements to SAM and Other CSP Modeling Tools Objectives:• Develop a cavity receiver option for SAM's molten salt power tower (MSPT) model and extend the model library to include additional heat transfer fluids • Convert the dispatch optimization code in SAM's MSPT model for use in other models that include thermal energy storage (TES). Key Results:• We incorporated a working cavity receiver model into SolarPILOT and SAM (version 2021.12.02). The receiver model incorporates an algorithm for view factors between two Nsided polygons that avoids the need for ray tracing and speeds up calculation times. The ability to mesh the cavity surface was added, but we found that meshing the surfaces significantly increases the computational burden of the problem. Meshing increases the simulation times from seconds to minutes. However, meshing all the surfaces results in around a 1% difference. Because of this, only the unmeshed option was offered through the SAM interface.

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