The research proposed in this PhD project relates to optical and structural design of heliostats, and the nexus between optical and structural design. During the design of a solar concentrator, it is common to refer to an “error budget” where various optical errors can be traded against each other in an effort to arrive at an optimum cost/performance design point. For heliostats, modern closed-loop control and calibration methods makes it possible to compensate for many optical errors associated with installation and tracking.  This leaves errors due to factors such as the stiffness of heliostat frame and mirrors, as well as the inherent mirror facet slope error, as the most critical variables for good performance.  Structural deflections of the mirror and structure are impacted by gravity and wind loads.

In this project, the objective is to develop improved methods of structural design of heliostats, to achieve the best trade-off of annual optical performance (under realistic gravity and wind loads) and low cost.  There are many variables to consider, that make this task complex.  For example, a single operating heliostat experiences fluctuating wind loads, at different orientation and under different solar conditions. Heliostat mirrors and structure must be designed for both optical performance (in any orientation while operating) and for survival in stow position.  Time-resolved data is available from heliostat testing in a wind tunnel from project partner University of Adelaide, which may be incorporated to avoid structural redundancy from conventional methods of determining wind loads.  The task is further complicated by the fact that heliostats in different parts of a solar field experience different wind loads, and have different optical performance. 

The methods developed should have universal application to designers of heliostat mirror and structural components, to help improve the state-of-the-art and allow efficient structural design and material usage to be minimised.  The PhD candidate will carry out this project as part of the ASTRI Heliostat project, and work closely with the ANU team developing low-cost sandwich mirror panel facets, in conjunction with industry.