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Surpassing the 2D Limit: A 600x High-concentration PV Collector Based on a Parabolic trough with Tracking Secondary Optics

2014; Elsevier BV; Volume: 57; Linguagem: Inglês

10.1016/j.egypro.2014.10.033

1876-6102

Thomas Cooper, Gianluca Ambrosetti, Andrea Pedretti, Aldo Steinfeld,

Optical Wireless Communication Technologies

We report on the design and performance of a novel 600x high-concentration photovoltaic (HCPV) collector. The design is unique in that it diverges from the predominant HCPV approach of a 3D concentrator mounted on a 2-axis tracker. We consider minimization of the cost per m2 of collecting aperture to be the most important aspect in achieving cost-competitiveness. Accordingly, we borrow from the knowledge of the more mature CSP industry which has shown the parabolic trough to be an effective and economical method to concentrate sunlight. To further leverage the advantages of scalability of trough geometries, the primary concentrator utilizes a construction based on inflated metalized polymer membranes as reflectors supported on modular concrete structures. With this design, aperture widths surpassing 10 m and trough lengths exceeding 200 m are possible. At a trough length of 200 m, the rated power of one collector is 500 kWp. To augment the concentration into the realm of HCPV, where use of high-efficiency triple-junction concentrator cells becomes economically viable, a novel secondary concentrating stage is employed, consisting of an array of tracking non-imaging concentrators arranged along the focal line of the primary. This two-stage line-to-point focus system allows for concentrations of over 600x, considerably surpassing the 2D limit of ∼200x inherent to trough-like geometries, while maintaining the advantages of a one-axis tracking trough primary concentrator. A full-scale prototype of the system has been constructed in Biasca, Switzerland. Year-round solar-to-electrical efficiency is expected to exceed 25%.