Environmental Engineering Reference
In-Depth Information
production now includes 16 fabrication lines in Malaysia, expanding from initial
facilities in theUnited States. It appears that this is a simple and rapid fabrication of
the basic CdTe absorber layer. It is reported (http://Wpww.greentechmedia.com/
articles/read/Thin-FIlm-Solar-Startup-Solexant-and-its-New-CEO/) that Nano-
solar and ISET (not in the
first 15 producers) make CIGS cells by a nano-ink
process, and that Solextant is starting to make CdTe cells using a nano-ink process.
Other
firms presently are using electrodeposition and reactive sputtering. Other
CIGS producers are Avancis, Solar Frontier, Global Solar, and Honda Soltec; other
CdTe producers are Antec, Abound Solar, and Primestar, now a part of General
Electric. A variety of technologies are represented here, not all proven. For example,
Solyndra, listed above as producing 67MWof CIGS cells in 2010, went bankrupt in
September 2011 [124]. Their innovation, a cylindrical geometry for the cell, to catch
a range of sunlight angles, was too expensive to produce, as might have been clear
from the start.
All of these processes involve production lines. A roll-to-roll process is used by
United Solar for
flexible multijunction Si cells, and by Nanosolar for its nano-ink
process. An illustration of a roll-to-roll production line for Si is shown in Figure 10.3.
In other cases, the production line carries glass panels, which are coated
sequentially. Figure 10.4 shows the production line of Abound Solar for
CdTe panels (http://Wpww.abound.com/solar-modules/manufacturing), said to
be 12.8% ef
cient.
The facility shown in Figure 10.4 accepts one glass panel every 10 s, which
emerges at the other end of the line 2 h later as a completed CdTe solar module
(http://Wpww.abound.com/solar-modules/manufacturing). At this rate, a 10 h day
produces 8
2880 modules, for a nominal daily volume of 0.288MWp
(at nominal 100 watts per panel). On this basis, 226 production days are needed to
reach 65MW, the stated annual capacity of the production line. This
rm has
funding for expansion of manufacturing capacity by 180MWp in Colorado and an
additional 600MWp in Indiana. Exemplary panels are said to have 12.8%ef
ciency.
This is the kind of company for which the future will depend upon the manufactur-
ing cost, which is not easily available.
3600/10
ΒΌ
Web move
Pay-off
chamber
Take-up
chamber
Bottom
Middle
Top
MW
MW
RF
n
p
n
p
n
p
i a-SiGe
i a-SiGe
i a-Si
Figure 10.3 Roll-to-roll processing line using
CVD deposition illustrated for three-layer silicon
cells [128]. The CVD processing stations here
include microwave and radio frequency heating.
This is similar to a line used by United Solar (see
Figure 7.12), where the moving foil or web is
stainless steel, 35.6 cm in width, as mentioned
following Figure 7.13. A simpler roll-to-roll
scheme is used by Nanosolar, with ink
deposition for the CIGS absorber layer. In both
cases, the foil is later cut up and mounted in
modules, extra steps that add to the cost.
