Environmental issues of material input in CDTE-module manufacturing Page: 3 of 8
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and have to be considered as inputs or
auxiliaries in other processes. These
materials do not directly endanger the
environment at that processing step.
Gaseous emissions e.g. CO, CO2 and SO2
are conspicuous which we could record
qualitatively only. Our estimations for the
climate gas emissions show remarkable
contributions to the environment. This is
also obvious for the reagents and
flocculating agents during the flotation
processes of raw ore materials. We have
identified acids or bases which regulate the
pH-value of the mud. Some reagents or
floating dirt contain water-polluting
substances like CuSO4 and ZnSO4.
3. PV MODULE MANUFACTURING
In order to identify critical substances
or to asses the risk potential during module
manufacturing, precise knowledge of
deposition conditions and techniques is
indispensable. This knowledge enables us
to determine the quality and the quantity of
process associated materials and PV
module embedded substances.
Correlated to the different manufacturing
techniques of CdTe-modules, layer
thicknesses differ by a factor of 5 (2-10
gm). CdS-layers are in the range of 0.2 gm
to 10 gm. Furthermore the amount of used
substances as input materials vary rather
high. In various cases, material utilisation
or the process efficiency (that is the ratio of
the deposited material to the input material)
is less than 50 % and comes close to 10%
for some deposition techniques. Our results
in the analysis of the four selected modules
show a remarkable mass range of the input
material Cd. As shown in Table 4, it differs
from 10 g to 530 g corresponding to a
factor of 53.
As a consequence of a low material
utilisation a relevant amount of critical
materials remains as residue in the
production facility. It represents an
uncertain potential of environmental and
health risks . The controlled handling of
these materials during the processing and
after the deposition is subject to safety as
well as to commercial aspects. Less input
of critical substances using deposition
techniques with high material utilisation
results in lower risk potential and reduces
material purchase cost at the same time.
Table 4: Minimum and maximum material
input of Cd, Te and S for the deposition of
CdTe- and CdS-Layer (4 selected modules)
Cd. Gd T. CTS C1 S CdCS
4. LEGISLATIVE LIMITS
No specific legislation for the
photovoltaics industry regarding the
environment exists for Germany, the
European Union, USA or in the WHO.
However, manufacturers are forced to
comply with the existing laws in their
country. The legislation in these countries
has clearly identified carcinogenic,
mutagenic and teratogenic substances. It
has regulated in a more general way the
manufacturing, use and disposal of such
material. Therefore it is a major task for the
industrial users to replace critical materials
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Steinberger, H.; Hochwimmer, R.; Schmid, H.; Thumm, W.; Kettrup, A. & Moskowitz, P. Environmental issues of material input in CDTE-module manufacturing, article, December 31, 1995; Upton, New York. (https://digital.library.unt.edu/ark:/67531/metadc666078/m1/3/: accessed May 19, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.