Comparison of conventional and telescopic heliostat fields at the same tower height

For the same height at the central receiver or beam-down optics, a telescopic heliostat field will have about twelve times the power rating of a conventional heliostat field. About a factor of three comes from increased field radius, and a about factor of four from improved land utilization.

For the same height at the central receiver or beam-down optics, a field of telescopic heliostats has about twelve times the power rating of a field of conventional heliostats. Of this factor of twelve, about a factor of three comes from increased field radius (the field radius is 14 times the tower height as opposed to 9 times) and about a factor of four comes from covering the land more densely with heliostat mirrors (81% mirror fill as opposed to 17%.)

Take for example the 160 m tower height of the solar plant now under construction in Crescent Dunes, Nevada. A telescopic heliostat field with beam-down optics topping out at a height of 160 m would have a heliostat field radius of 2225 m, and 81% mirror fill, giving an approximately 1.3 GW solar plant instead of the 110 MW the plant being built at Crescent Dunes. Significantly, with telescopic heliostats, this full-sized power plant would be ground-mounted rather than on a tower.

The radius/tower ratio of 14 for a field of telescopic heliostsats was calculated in a previous post.

The mirror fill of 81% for a field of telescopic heliostats was estimated as follows.

The packing efficiency of circles in a hexagonal arrangement on the plane is 0.907. Taking the mirror fill in the solid phase of the heliostat field to be 90%, the previous calculations assumed the mirror fill in the outermost ring of heliostats would be 0.6 of this value or 54%, so, on average, the mirror fill in the gas phase of the heliostat field will be roughly the mean of 54% and 90%, or 72%. Since the gas and solid phases of the heliostat field have equal areas, overall the mirror fill is the mean of 90% and 72%, or 81%.