Autonomous light-weight heliostat with rim drives

Abstract

Several approaches for cost reduction of heliostats, which fit well to each other, are combined to a new heliostat concept to achieve the current challenging cost objectives: The wind loads are reduced by appropriate manipulators which reduces weight and cost of the heliostat structure and the ground anchor foundation. Laminated mirror facets are of high reflectivity and shape accuracy and of low weight. The low weight is advantageous for the dimensioning of the bearings and regarding energy consumption. Energy consumption is further reduced by a highly efficient drive train. Thus, small capacity of the wireless energy supply of the autonomous heliostat is sufficient which reduces significantly its cost. By the combination of horizontal primary axis with rims and winch wheels a cheap and precise solution for the drives was found. Ray tracing calculations show that the losses due to the compromised angle range are negligible. With the new heliostat concept the current cost goals seem to be achievable.

Latitude-orientated mode of non-imaging focusing heliostat using spinning-elevation tracking method

“…Since the solar images of mirror facets were captured from morning to afternoon with hour angle ranging from x = -58.6°to x = 55.9°, the orientation of focused spot were seen rotated to follow the change of spinning angle. Wireless control of heliostat tracking is a new trend of control system for a large-scale heliostat field as it can reduce cost for the cabling and electronic control system (Kubisch et al, 2011;Pfahl et al, 2013). The globally identical characteristic of LO-NIFHs will not only allow the sun-tracking of heliostats in a heliostat fields to be performed through a central control system that uses wireless broadcasting method, but also allow the control to be extended to different locations of heliostat fields globally with an appropriate correction to the local time.…”

Advances in solar tower technology

“…Further cost reduction can be realized, especially by new laminated mirror concepts, by optimizing the size of the heliostat and by taking new findings regarding wind load determination into account. As described in Ref , in order to prove the concept and the cost estimations, a prototype of 8 m 2 shall be built.…”

3rd generation rim drive heliostat with monolithic sandwich panel

“…At rim drive heliostats, the accuracy requirements and the wind loads on the drive units are comparably low because of the long lever arms of the rims which significantly reduces the the demand for strong mechanical structure and precision of the drives compared to conventional heliostats. Previous developments of a rim drive heliostat have been presented in [1], [2] and [3]. Here, investigations of the dynamic wind load behavior and the improvements of the 3 rd rim drive heliostat generation are presented ( Fig.…”