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422 A COmpREHENSIvE GUIDE TO SOLAR ENERGy SySTEmS

frames, also reduced in energy consumption. C­Si modules had the highest energy learn­
ing rates, which were mainly driven by improved silicon production. Louwen et al. [41]
re­assessed the body of pv LCAs over a 40­year period and corroborate Gorig and Breyer’s
findings of decreasing CED for pv systems and modules. They found that EpBT dropped
from around 5 years in 1992 to currently under 1 year for poly­Si and just over 1 year for
mono­Si concurrent with rapid growth in capacity. Overall, they found that CED decreased
11.9%–12.6% with each doubling of capacity.

21.3.3 Future Possibilities
The future of pv technology development is very difficult to predict; however, it may be
likely to experience a high potential for decrease in energy costs and an increase in efficien­
cies for the industry. It is expected that EpBTs will therefore decrease and EROIs will likely
increase. Of the very little information available to predict these things, it seems to be mostly
positive for pv. Overall, new manufacturing technologies and application methods, such
as advanced production processes, reducing Si and other raw materials consumption, and
increasing material recycling rates are all avenues for improving pv performance and EROI.
As calculated by Gorig and Breyer [40], the learning rate for pv modules is 17% and for
pv systems it is 14%. They expect strong development until 2020 and forecast an EROI of
20–60:1 approaching the year 2030. The study by Louwen et al. [41] reinforces the idea that
CED will decrease for pv modules in the future. They expect the production of mono­Si
to be influenced by a stronger learning rate to poly­Si modules due to the fact that mono­
crystalline Si is more energy intensive and thus benefits most from energy and material use
reduction. Overall, lifecycle energy costs have realized real improvements given develop­
ments in terms of material usage. Energy efficiency continues to improve for a range of pv
technologies available for economic electricity generation. The most noticeable improve­
ments have occurred for CdTe technology in terms of overall systems improvements [33].
This is without the serious recycling efforts expected in the future of pv manufacturing.
Insight into recycling methods and what they mean for the EpBT and EROI of pv are
still being developed. Goe and Gaustad [42] predict that recycling rates are likely to have
the most impact for low efficiency modules, especially those with aluminum frames, due
to the less complex nature of their composition, but rates might be low due to small re­
turns for customers. more complex high efficiency modules might realize low recycling
rates due to the potential high costs of reintegrating them into the manufacturing process.
Overall they caution that realized recycling rates are likely to be low without regulation,
or mandatory recycling. They estimate, however, that exhaustive recovery of pv materials
could have the potential to reduce EpBTs of mounted modules by more than half for ma­
ture Si­based and thin­film technologies.
As we can see, the industry is moving at a very fast pace toward increased efficiencies,
lower CED, thus lower EpBT, and therefore, we assume, higher EROIs. We can also start
to see that there are many assumptions in making industry­wide statements concerning
pv technology deployment. There are many variables that are specific to geographies,