Page 107 - A Comprehensive Guide to Solar Energy Systems

102 A COMPrEHENSIVE GUIdE TO SOlAr ENErGy SySTEMS

FIGURE 5.12 Principle of roll-to-roll (R2R) production of planar p-i-n perovskite solar cells.

can be considered truly sustainable, or be incorporated effectively into a viable circular
economy in South Africa, or elsewhere in SSA.
Numerous lifecycle analysis studies have shown that substrates represent a large
proportion of the embodied environmental and economic costs of PV cells [58], and
that these costs are lower for PET substrates than glass [59]. Analysis has also shown that
laminate materials such as EVA, represent a significant proportion of the embodied costs
of thin-film modules [28], making its recovery desirable. So there is a need to develop new
delamination methods, new laminate materials, and/or alternative flexible transparent
substrates which are compatible with delamination processes.
PPV technologies utilize numerous critical raw materials. The traditional
transparent conducting oxide used has been ITO. However, due to the rising price
and global criticality of indium, resulting from supply bottlenecks and demand for
ITO for flat screens, this has been replaced by FTO on glass in solar cell applications.
replacement with FTO on PET has been problematic due to the high temperature PVd
process used for FTO deposition, and degradation of PET in the process. Mitigation
strategies enabling ITO substitution may result from research into new low tempera-
ture methods for deposition of transparent conducting oxides such as rF magnetron
sputtering [60–62]. Substitution with graphene-coated PET may be a solution, how-
ever, cost is currently prohibitive for commercial applications. Carbon nanotubes,
which can be printed on substrates, have also been explored as conducting layers [63].
Another potential critical raw materials issue arises from the use of ru in the dyes for
dSSCs, and there is much work on fully organic dyes as replacements [64]. Their use