Civil Engineering Reference
In-Depth Information
Table 12.5
Photovoltaic second generation summary
a-Si (amorphous silicon)
Effi ciency
5-7%
Degradation
2% in the fi rst initial months
Advantages
Cheap to produce
Absorbs light better hence they are thinner and cheaper
Can be applied as a thin layer to a variety of material
both fl exible and non-fl exible
Good for building integrated PVs
Disadvantages
Poor cell effi ciency
Fast degradation
Low effi ciency
Larger surface area required for commercial installation
Compound semi-conductors
Effi ciency
CIS (copper indium gallium) - 12%
GaAs (gallium arsenide) - up to 40%
CIGS (copper indium gallium selenide) - 12-15%
CdTe (cadmium telluride) - 10%
Degradation
Varying
Advantages
Has not seen the high degradation experienced by
amorphous silicon
Overall the initial development of the modules is
impressive
GaAs is good for high temperature performance and
effi ciency
CdTe has a low cost production process
CIGS and CIS have good effi ciency and low cost
production
Disadvantages
Requires thicker layers than amorphous silicon
Indium is expensive
Issues with toxic gases used in the production of CIS
and CIGS
GaAs both material and production is expensive
Cadmium is toxic
will be able to assess if their lifetime will be proven compatible with fi rst
generation technology. Table 12.5 summarizes the effi ciency, degradation
and the advantages/disadvantages of second generation PVs for two models.
12.4.3 Third generation
Third generation PVs are still heavily under research. Although develop-
ment of this technology has been ongoing for about 20 years, they are only
now starting to emerge on to the market. It is expected that third generation
photovoltaics will combine the best of both the fi rst and second generation
technologies; hence they should have high effi ciency and low cost. The
original defi nition of 'third generation' was that the technology had to have
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