Environmental Engineering Reference
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lm technologies, mainly based
on CdTe cells and modules, the cost per W is generally slightly lower, but this does
not translate into lower LCOEs because of the signi
The
gures above are for c-Si modules. For thin-
cant difference in ef
ciency:
for the CdTe cell the
gure is in the range 6
10 % whereas for c-Si it is more than
-
double that, at 15
20 %. In spite of this, and although at a much lower scale, thin-
-
lm modules are being deployed at commercial level, since they can be easily
integrated into buildings, particularly where there is glass that also allows light
through (Building Integrated PV (BIPV)).
The most dif
cult part of this discussion, but also the most challenging and
relevant, concerns the future prospects for continued cost reductions and mass
deployment of PV systems of all types. Some things are clear: the versatility of this
technology (scalability from domestic to utility scale systems, adaptability to dif-
ferent types of consumer -residential, industrial, commercial- and off-grid systems
including islands), makes its future look rather promising at world level [
3
]. This is
especially so for countries and territories where modern electricity networks are not
properly developed, i.e. for most of the world, including virtually all emerging
markets, the whole of Africa and less developed countries elsewhere. For developed
countries, mainly OECD, the technology is especially suitable for distributed
generation and consumption, i.e. residential use, small to medium industry and
commercial
rms, as a consequence of its scalability and democratic character.
In spite of all this, the future hinges crucially on the future evolution of module
and system prices and the LCOE, which also depends in turn on possible ef
ciency
improvements. For one thing, it is clear that PV-module prices cannot go on
decreasing at past rates for long, since they have already reached fairly low levels.
Moreover, their share in total system costs has decreased considerably and is no
longer the main component. Costs will therefore have to be brought down via
Balance of System (BoS) cost components such as inverters, miscellaneous electric
equipment, mounting racks, administrative costs of various kinds, labour and site
preparation. There is still ample room for this downwards trend to go on, associated
with the continued mass deployment of the past two or 3 years. But while it is true
that the European market has stalled to some extent, the Latin American, Middle
East, and other emerging markets have taken the lead and are investing heavily in
all kinds of renewables, including PV. Thus, the
'
learning-by-doing
'
cost reduction
effect can be expected to continue working.
The main cost measure, i.e. the LCOE, can also be cut down by improving
ef
ciency. The current commercially available ef
ciency levels are in the range of
15
ciency levels of up to
40 % for c-Si cells and up to 30 % for CdTe at pre-commercial stages have been
reported by researchers in R&D laboratories. It is also of interest to note that the
maximum attainable ef
-
20 % for c-Si cells, and 8
-
10 % for CdTe. However ef
ciency for concentrated solar PV cells has been reported to
be around 90 %, although this technology is still at its early laboratory development
[
22
]. Nevertheless, mass deployment and cost reductions will bring with them
increased pro
ciency improvements
can be rightly expected. Reductions in public support schemes can also be expected
to encourage cost reductions, because part of the support received by the demand
ts and funding for research, so that future ef
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