Impact of a Partial Solar Eclipse on the Direct Normal Irradiance and Flux Distribution in a Solar Tower System

Conceição, Ricardo Filipe Carrão, Gonzalez-Aguilar, Jose, Romero, Manuel, Barreto, Germilly Reki Morais

ISES Solar World Congress 2025 · Fortaleza, Brazil · 2025-11-03
Published by International Solar Energy Society (ISES)

Abstract

A novel study of the effect of a partial solar eclipse on a Solar Tower facility is reported. During the eclipse, a temporary, yet significant reduction in direct normal irradiance (DNI) was observed, with a relative reduction considering the clear-sky case of 23.63%. Ray tracing was performed for the single heliostat used for this experiment, to infer if for a clear-sky scenario, the flux map changes its shape during the eclipse period. It was confirmed by calculating the structural similarity index measure, which value was of 0.98, that the shape throughout the eclipse should be similar. Photographs were then taken at the light spot when pointing the selected heliostat for the experiment, showing that not only the DNI was reduced, but the spot shape also suffered deformation during the eclipse.

Keywords

CSP, Heliostat field, Flux map, DNI, Solar eclipse.

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