A coupled structural-optical analysis of a novel umbrella heliostat

Abstract

Heliostats account for 40–50% of the total cost of a solar tower power plant, so optimizing their structural and optical performance is critical to overall plant feasibility. In this paper, an ‘umbrella’ support structure was proposed to improve the mechanical properties of the heliostat, particularly in the presence of typical wind loads. The proposed structure was compared against a traditional heliostat structure in terms of its displacement and stress values (using ANSYS) and its optical efficiency (using TracePro). To cut down the structure’s weight (and cost), the proposed heliostat structural design was optimized through an orthogonal, coupled (structural—optical) modeling approach. The results show that a 31.7% weight reduction (from 5397.4 kg to 3685.3 kg) is possible with the optimized design, with only a minimal change in the mean optical slope error (which increases from 2.8mrad to 3.2mrad, and can be considered as negligible for heliostats near the central tower). In summary, the proposed ‘umbrella’ heliostat design provides a viable path towards significant 17.7% cost savings (via less steel) with a negligible loss in optical efficiency.