Photovoltaic Power Generation - Renewable Energy: Technology, Economics and Environment - page 280

of a fluorescent collector that also ensures excellent legibility throughout the
day by its light collecting capacity based on total internal reflection. Light is
emitted only in areas that are printed on rear side (i.e. only the numbers are il-
luminated). A light-emitting diode serves as light source. Such illumination
systems are also suitable for large-surface information panels, to illuminate
street nameplates and also suitable for advertising purposes.
− Information panels for stops of public transportation vehicles (like buses,
trams). Often stops for public transportation vehicles have no power supply for
light or information systems because of the high costs for the cables. Photo-
voltaic power supply systems allow operating information panels that receive
information on schedule deviations by radio. Current departures or delays may
be displayed online to the waiting passengers on LCD basis. In addition, in the
dark, energy-saving LED light guiding plates illuminate the displays. In con-
junction with a motion detector, illumination may be controlled as required in
times of low radiation. Larger PV systems also allow illuminating advertise-
ments and make thus an additional income accessible.
− Repeater and base stations for mobile networks. The most important market for
commercial, industrial photovoltaic off-grid applications is telecommunica-
tions. In view of the ongoing proliferation of cellular phones and other wire-
free telecommunication services, and the simultaneous demand for unlimited
network availability, there is an increasing demand for autonomous power sup-
ply regarding telecommunication network infrastructure; placing the highest
requirements on the availability of such supply systems. Oversized photo-
voltaic generators and battery accumulators meet such high level requirements.
For reliable and cost-efficient operation, such power generation systems are
equipped with algorithms for telediagnosis and telemonitoring, so that mainte-
nance can be performed on demand.
− Solar home systems. High investment costs for the power distribution infra-
structure in conjunction with a low power demand hinder grid connection of
remote, scarcely populated areas, particularly in developing countries. This ap-
plies to roughly 2 billion people who do not have any access to the grid, and
this figure is not likely to diminish within the next decades. This is why stand-
alone systems gain increasing importance. Therefore solar home systems repre-
sent a technically and often also economically favourable solution for basic
electrification of rural areas in developing and industrialising countries. Such
electrification is intended to cover the basic requirements for lighting and in-
formation of households. Solar home systems normally consist of a 40 to 70 W
solar module, a 12 V lead-acid battery of an approximate capacity of 60 to
120 Ah, a charge controller, and the consumers. Typical consumers are energy
saving lamps, radios and black and white television systems. In addition, there
may be centrally located communal appliances such as water pumps, cooling
facilities, e.g. for medication, for video sets for education and advanced train-
ing purposes, for medical appliances etc. For such system most commonly
ring the advantage of high energy

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