Stand alone solar powering for fiber-in-the-loop systems

Abstract

A key concern in fiber-in-the-loop systems is powering end-loop optical network units (ONUs) with the same reliability that is provided to POTS customers today. This paper examines the technical and economical feasibility of using Stand Alone Solarphotovoltaic (SAS) systems for powering these units, In these systems, arrays of photovoltaic cells located at or near !he ONU are connected to a battery and the ONU electronics. During normal sunlight conditions, electricity from the panels powers the electronics and charges the batteries. During periods of poor or no sunlight, the energy stored in the batteries powers the load. The use of solar powering for general telecommunications applications and the factors which make the technology attractive for this specific application are discussed. Then, a demonstration SAS system that was installed in December 1991 to study some of the technological issues in solar powering ONUs is described and its economics are examined. One conclusion of this study is that while SAS is not a ubiquitous solution for powering ONUs, it may be cost-effective today in areas of the country with high insolation and loops (distance between the ONU and the location that provides power and reserve) longer than 5, OOO feet.Furthermore, anticipated improvements in solar panel efficiency and cost will extend the applicability of SAS into areas with moderate and low levels of insolation.