Selection of new technical inventions is based on 'survival of the
cheapest', according to the biologist Julian Vincent. After every
invention there is an explosion of new applications of which in the course
of time the economically fittest remain. This will be certainly true for
applying solar cells in the architecture. In the meantime there are more
than thirty kinds of solar cells. From poisonous cells that contain cadmium
to biological cells from 'pure nature'. What will evolve from
this multitude is the question.
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At this time mono-crystalline, poly-crystalline and amorphous-silicon are the most applied systems. Amorphous-silicon is a collective name for cells in which a thin layer of silicon is sprayed on a carrier of for example glass or metal. A system with many possibilities: mats, flexible foils and even translucent panels can be made. By bringing silicon on a transparent carrier using patterns part of the light is passed through.
The cost of sun panels is expressed in guilders per watt.
According to this criterion the crystalline cells are for the time being
in the lead. Crystalline cells consist of silicon-wafers covered by glass
or plastics.
Poly-crystalline cells are uniform in colour while mono-crystalline have
a sort of mother-of-pearl structure. The tiles of ca. 100x100mm are combined
into PV-panels. The panels can be applied vertically in the façade
but for a favourable relationship between investment and proceeds the
panels are generally placed on the roof, tilted to the south.
The proceeds of amorphous systems are now still considerably
less than that of crystalline. But because of the much simpler production
method this system is expected to be competitive within a few years. Encouraging
for designers because this system is much more flexible than the stiff
crystalline tiles, which are often only available in bright blue. Amorphous
cells not only offer more variation in colour and texture, but also the
limitations with regard to the placing on the south side can perhaps be
discarded.
As with the integration of each new invention there is also by the introduction
of PV-panels a phase in which existing products are imitated. Just like
the first synthetic bicycle was almost an exact copy of the traditional
steel bicycle. At the introduction of sun cells there was first sought
for integration in known building systems such as roof tiles. But a renewing
architecture can only be created after we recognise the specific characteristics
of this new technology.
jv