Technical and Economic Aspects of Gridconnected Solar Photovoltaics in Brazil - Implementing Environmental and Resource Management - page 57

Therefore, if this were the factor to be considered, the preferred option would be
pc-Si closely followed by CIS.
In addition, with the above values one can calculate the EPBT (Energy Payback
Time) associated with each technology: considering a rate of conversion effi-
ciency from primary energy to electricity of 42% (typical for EU countries), the
calculation for the reference case leads us to the following results: 2.43 years for
CIS, 2.47 years for pc-Si, and 2.60 years for a-Si.
Finally, in the same report (Jungbluth et al. 2008) the normalized LCA (Life
Cycle Assessment) scores of seven module technologies for slanted-roof mounted-
panel application, including the three types detailed in the case study, were com-
pared, . A bar graph shows the final value obtained after a full LCA that consid-
ered ten impact categories (i.a. mineral extraction, fossil fuels, respiratory effects,
climate change, carcinogenics, ecotoxicity, acidification and eutrophication),
weighted in the final step using the method “Eco-Indicator 99” (in its hierarchist
variant with an average weighting set). The values of interest for us are: approx.
3.8*10 -3 points/kWhel for CIS, approx. 4.6*10 -3 points/kWhel for pc-Si, approx.
4.9*10 -3 points/kWhel for a-Si (the lower the better). Thus if the decision were to
be taken based on this indicator the preferred technology would be CIS. For com-
parison, the value in the same scale corresponding to the Brazilian electricity sup-
ply mix in low-voltage grid (assuming 84% hydro, 11% conventional thermal, 3%
biomass and 2% nuclear) would be 0.011 points/kWhel (Ecoinvent 2007), that is
one order of magnitude higher than the results for PV.
The conclusion of this short review is that, in the reviewed LCA studies where
the three technologies used in the case study were compared to one another
(Frankl et al. 2004, Jungbluth et al. 2008, Ecoinvent 2007), the CIS (or CIGS) op-
tion obtains better results or is practically equal in all occasions, therefore one can
state that from an environmental perspective it would be the most preferable op-
tion.
6.3.8 Conclusions of the Case Study
The conclusion that can be drawn after the realisation of this practical technical
study is that, in this area of the state of Santa Catarina (and in most areas of Bra-
zil), the building-integrated grid-connected photovoltaic systems proposed would
be technically feasible but not financially attractive without any improvement of
conditions, as explained in the cost considerations section (see 6.3.5). But the
situation would become significantly advantageous if a feed-in tariff consisting of
a remuneration of the generated electricity at three times the retail sale price, in
line with the one enacted in Germany in 2004 (Stryi-Hipp 2004), were introduced.
In that case even the most expensive alternative (the one with CIS solar modules)
would become feasible in areas with higher irradiation like the states in the North-
east of Brazil; the configuration with polycrystalline solar modules would become
feasible and lucrative even in the areas with lower irradiation; and the configura-
tion with a-Si solar modules would offer a very interesting remuneration (IRR
above the inflation rate) in any location. These positive prospects would be further