Technology Status - NET Nowak Energie & Technologie AG

SOLAR PHOTOVOLTAIC POWER
A Brief History of Photovoltaics
The direct relation between light and electricity was demonstrated by
Becquerel in 1839, but it was not until the development of diodes in 1938 and
transistors in 1948 that the creation of a solar cell became possible. Bell Labs
patented the first solar cell based on silicon in 1955. This was the starting
point for higher cell efficiencies, leading to the commercialisation of
photovoltaics.
Photovoltaic (PV) technology has been used in space and terrestrial
applications from small appliances like calculators to large-scale, multimegawatt
power stations.
Technology Status
PV technology and applications are characterised by their modularity – PV can
be implemented on virtually any scale and size. The overall efficiency of
systems available on the market varies between 6% and 15%, depending on
the type of cell technology and application. The expected life span of PV
systems is between 20 and 30 years. The solar modules are the most durable
part of the system, with failure rates of only one in 10,000 per year. Some
components, e.g. the inverter and battery, have to be replaced more regularly.
Experts expect crystalline silicon (market share 85% in 2002) to remain
dominant in the coming years and thin-film solar cells to be considerably less
expensive in the medium to long term. Different cell technologies can exist
side by side. Some applications require high efficiency in a small space
(crystalline silicon), while others need less expensive material covering a
larger area (thin-film cell technologies).
Individual PV cells are interconnected and encapsulated between a
transparent front, usually glass, and a backing material to form a solar PV
module. PV modules for energy applications are normally rated between 50
and 200 W. The PV module is the principal building block of a PV system and
any number of panels can be interconnected in series or in parallel to provide
the desired electrical output.
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