Photovoltaic-Powered Lighting System For Overhead Highway Guide Signs

The problem: A safety hazard affected motorists traveling through a remote area in Brevard County near the St. Johns River on the eastbound Bee Line Expressway (S.R. 528). At that point the Bee Line splits, sending Titusville- bound motorists to the north, and Central Brevard- bound travelers to the south. Because of the high cost of extending utility service several miles from the nearest distribution point, the overhead guide signs were not illuminated, and at such a critical juncture on the 65-mph highway, it was difficult, if not impossible, to read them at night. The problem-solvers: Since 2.5 million vehicles per year travel the Bee Line\u27s north and south arteries from the Orlando area, the problem was critical. Therefore, in July of 1987, under the sponsorship of the Florida Department of Transportation and the Florida Governor\u27s Energy Office, the Florida Solar Energy Center (FSEC) undertook to design, install and monitor the performance of a prototype photovoltaic-powered lighting system for overhead guide signs. The solution: Photovoltaics, the technology of converting sunlight to direct-current electricity, was the method of choice because it has been shown to be a viable option for many remote and atypical electric power systems. Work began by conducting an extensive literature search on similar applications and pertinent Federal Highway Administration and American Association of State Highway Transportation Officials standards and regulations. Photometric and electrical characteristics for a wide variety of lamps and fixtures were evaluated to identify the most efficient combination that would meet the illumination requirements. This was necessary to minimize the size of the photovoltaic system needed to power the lighting system