Moonlight concentration experiments of Badaling solar tower power plant in Beijing

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.