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For large-scale central receivers, authors have proposed a new indirect measurement method of the concentrated solar flux distribution of the heliostat field based on moonlight concentration experiments. The flux density distribution of the sunlight on the receiver surface could be estimated using the moonlight concentration ratio function of the heliostat field and the direct normal solar irradiance. But a natural question are how the sun and moon differ as light sources and what effect these differences have on the distribution of concentration ratio on the target by light concentrating experiments. Thus, a single mirror heliostat with azimuth-elevation drive was installed in the 1MWe DAHAN solar tower power plant in Beijing. The heliostat mirror was a standard outer RP3 solar-trough mirror facet. The heliostat was essentially designed to investigate and compare different sun shapes and moon shapes for accurate solar concentrator optical simulations. Comparisons of experimental and simulation results on the target plane for the sun and the full moon show that the two light sources have the similar effects on the concentration ration distribution. [ABSTRACT FROM AUTHOR]

In the solar thermal tower power generation system, the measurement of concentrated solar flux distribution on the receiver aperture is important for optimizing and operation of both heliostat field and receiver. For large-scale central receivers, this paper proposes a new indirect measurement method of the concentrated solar flux distribution of the heliostat field based on moonlight concentration. The flux density distribution of the sunlight on the receiver surface could be estimated according to the moonlight concentration ratio function of the heliostat field. The moonlight concentration ratio function on the receiver surface: CR(x,y)moon=I(x,y) / DNImoon, where I(x,y) is the illuminance distribution, DNImoon is direct normal illuminance of the moonlight. Under ideal conditions, CR(x,y)moon=CR(x,y)sun. Thus, the concentrated solar flux density F(x, y) can be obtained by: F(x,y)=CR(x,y)sun•DNIsun=CR(x,y)moon• DNIsun. This measurement method really measures illuminance distribution on the receiver aperture using a stationary array of illuminometers and the direct normal lunar illuminance (DNImoon) using a reference illuminometer on the dual-axis moon tracker. Based on this concept, moonlight concentration experiments were carried out at Badaling Solar Tower Power Plant in Beijing in the full moon night of September 24, 2018. [ABSTRACT FROM AUTHOR]

A single mirror heliostat with azimuth-elevation drive was installed in the 1MWe DAHAN solar tower power plant near Beijing. The heliostat mirror is a standard outer RP3 solar-trough mirror facet. The heliostat was configured for accurate measurement of tracking performance by using a single small flat reflector. Equivalently, most of the reflector surface was covered with newspapers glued to the glass, leaving only a circular mirror region of 4 cm in diameter at the mirror center. A white target and ground mounted camera were used to monitor the location of the reflected image and verify the Authors’ tracking error correction model. During the work, it was necessary to revise the general azimuth-elevation tracking angle formula and associated error correction model to consider the specific definitions of the error parameters. After this revision, the performance of this extended general tracking angle formula and tracking error correction model were verified during three days of continuous operation. This paper presents the tracking error correction procedure and the results of applying it to this example. [ABSTRACT FROM AUTHOR]