Solar Energy Vol. 65, No. 3, pp. 159–170, 1999 1999 Elsevier Science Ltd  Pergamon PII: S0038–092X(98)00129–7 All rights reserved. Printed in Great Britain 0038-092X / 99 / $ - see front matter SOLAR FIBER-OPTIC MINI-DISHES: A NEW APPROACH TO THE EFFICIENT COLLECTION OF SUNLIGHT , , ² DANIEL FEUERMANN* and JEFFREY M. GORDON* ** *Center for Energy Environmental Physics, Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus 84990, Israel **The Pearlstone Center for Aeronautical Engineering Studies, Department of Mechanical Engineering, Ben-Gurion University of the Negev, Beersheva 84105, Israel Received 13 February 1998; revised version accepted 9 October 1998 Communicated by LORIN VANT-HULL Abstract—A new concept for efficient solar energy concentration and power delivery is proposed — one that offers substantial advantages in efficiency, compactness, reduced mechanical loads, and ease of fabrication and installation relative to conventional solar designs. The design exploits the availability of low-attenuation optical fibers, as well as the practical advantages of mass producing highly accurate very small parabolic dishes. The system’s building block is a miniature (e.g. 0.2 m diameter) solar dish which concentrates sunlight into a single optical fiber. The fiber transports power to a remote receiver. A second-stage concentrator can boost flux levels to those approaching the thermodynamic limit and can be performed either in each individual dish or collectively in one or more larger devices at the entrance to the remote receiver. Collector modules, close-packed with mini-dishes, are mounted on individual trackers close to the ground. Systems are modular and can be employed in central power generation ranging from a few kilowatts to tens of megawatts. Designs for maximum efficiency attaining collection efficiencies as high as 80%, and maximum-concentration designs realizing flux levels of 30 000 suns, are achievable.  1999 Elsevier Science Ltd. All rights reserved. 1. INTRODUCTION To date, the conventional wisdom has been that: (1) for solar collectors, ‘larger is better’ due We are proposing a new approach to the efficient to economies of scale; and (2) collected sunlight collection of sunlight, in particular for high temperature / high-flux applications. At the heart of the system is a small (e.g. 0.2 m diameter) solar concentrator with an optical fiber that transports concentrated sunlight to a remote receiver (Fig. 1). A number of such mini-dishes constitute modules (Fig. 2) that are mounted on individual trackers and serve as the building blocks for a solar field (Fig. 3). A solar field would comprise a large number of modules. Each system component is adequately small to permit mass production of precision elements with existing technologies. The modularity of the design permits system sizes ranging from as little as a few kilowatts to as high as tens of megawatts. Our notion exploits recent advances in high-concentration optical designs and in fused silica optical fibers that possess a high transmissivity averaged over the solar spec- trum and can withstand high flux. We refer to this remote irradiation assembly as a solar fiber-optic Fig. 1. Cross-sectional drawing of a solar fiber-optic mini-dish. mini-dish system. The primary concentrator is a paraboloidal dish reflector of rim half-angle f and diameter D. A small flat mirror below the focal plane of the dish re-directs rays reflected from the dish ² Author to whom correspondence should be addressed. Tel.: downward so that an upward-facing absorber can be used. The 1972-7-659-6923; fax: 1972-7-659-6921; e-mail: fiber is enclosed in a protective sleeve. One extreme ray is jeff@menix.bgu.ac.il shown traced to the absorber. 159