Design of efficient stamped mirror facets using topography optimisation

Abstract

Significant cost reduction is required to improve the competitiveness of concentrating solar power. Heliostats make up a significant proportion of the capital cost of solar tower plants, with low-cost, high-performance designs required to meet levelised cost of energy targets. Lightweight stamped mirror facets are seen in leading commercial solar tower plants, with low manufacturing costs and high optical performance. Here, topography optimisation is investigated as a tool for designing lighter and structurally efficient stiffening bead patterns for stamped mirror facets. A case study is presented demonstrating topography optimisation as a promising tool for facet design, with tailored optimisation approaches incorporating wind and gravity load cases, manufacturing constraints, and combined optical-structural objectives. A range of concepts were generated, and their performance assessed to develop a design framework for high-performance supports. Wind loads in the stow position were found to influence and limit weight reduction more than gravity loads during operation. For the various concepts generated by optimisation, a common geometric feature was clearly-defined radial beads from the mounting points to a peripheral bead, driven by the need to overcome high bending stresses. Prototyping stamped structures is typically expensive. A low-cost and accessible rapid-prototyping method for stamped facets was developed using incremental sheet forming. A framework is presented for fabricating facets incorporating optimised supports, with photogrammetry and deflection tests enabling rapid assessment and structural modelling validation.