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Chapter 5 • Sustainable Solar Energy Collection and Storage 103

mitigates the criticality issue associated with ru, and they are compatible with current
dyeing processes.
An alternative strategy to substitution for mitigating resource criticality issues is to
decouple supply from primary production by developing secondary supplies from within
the circular economy, including supplies from end-of-life devices and cascaded materials
derived from wastes available within the circular economy, that is, industrial symbiosis.
Examples of lab-scale processes for production of PPV materials from waste include the
production of perovskites from lead-acid car batteries [65], the production of carbon-
based counter electrodes from batteries [66], the use of conductive glass from TFT-lCd
screens as dSSC counter electrodes [67,68], and the generation of platinised counter
electrodes for dSSCs from waste thermocouples [69].
Plastic substrates are derived from crude oil, so biologically derived alternatives are an
environmentally attractive prospect. Transparent flexible substrates composed of cellulose
nanocrystals can have high transparency and low surface roughness, and these have been
used in OPV where they offer easy recyclability due to the solubility of the substrates in
water [70]. Where plant-derived materials are used, there is also a carbon sequestration
benefit.
Priority research areas to enable full lifecycle optimization include: methods of module
lamination/delamination which do not degrade material components of cells and mod-
ules; substitution of critical raw materials; processes for generation of secondary resources
from ‘wastes’ available within the circular economy; development of biologically derived
components such as cellulose based substrates; and methods which enhance resource
and energy efficiency of roll-to-roll manufacturing, such as solvent capture, and recovery
of production scrap.

5.10 Conclusions

The convergence of energy demand, population growth, sunlight, and low cost solar cells,
suggests that SSA will see, over the next few decades, a huge and rapid expansion in use
of off-grid PV solar systems, particularly for rural locations. This will require an enormous
volume of solar cells and batteries. The installation, use, and end-of-life management
of these systems may cause serious environmental damage if done in an unregulated,
irresponsible way. But, if built on circular economy principles, management of PV systems
and their waste components could provide a large, widespread, regional industry, with
major economic, environmental and social benefits for the region.
developing and adapting PV technologies for local conditions, materials availability,
available logistic chains, and end-of-life infrastructure, education and local skills, will be
essential if the off-grid electrification of rural Africa is to be a success, technologically,
economically, and environmentally. It is not only a great challenge, but also a great
opportunity, for the scientists, industries, businesses, technologists, and regulators of the
region. It is vital that the informal sector of SSA be involved in any solution, and universities