Page 238 - Materials Chemistry, Second Edition

Comparing Various Indicators for the LCA 227

Fig. 9 GWP of a 3 kWp PV system (Ito et al. 2010 and Ecoinvent)

5 LCA of 1 kWh of Electricity

5.1 Introduction

To obtain the impact of 1 kWh of electricity, we can simply divide the impact of a
3 kWp PV system by the Lifetime Energy Output, which is calculated as follows:
LEO ¼ YEO lifetime kWh½ Š ð7Þ

with LEO = Lifetime Energy Output [kWh]
YEO = Yearly Energy Output [kWh/year]
Lifetime = Expected lifetime of the PV system [years]
In the Ecoinvent report n°6, a lifetime of 30 years is assumed. An IEA-PVPS
report (International Energy Agency 2009) also suggests to use a lifetime of
30 years. Some authors, however, suggest lifetimes of 20 or 25 years (Varun et al.
2009a). Therefore, two lifetimes will be evaluated, a pessimistic estimate (20 y)
and a realistic estimate (30 y). Also the impact of the irradiation is important, since
higher irradiation results in more electricity production (a higher YEO) and thus a
lower per kWh impact (see Eqs. 2, 3, and 4).
As the focus of this chapter is on residential systems, which is dominated by
multi c-Si PV systems (Raugei and Frankl 2009), we will from here on mention
only the results for multi c-Si systems. This does not have any major implication
for the overall conclusions since the environmental impact of the production of a
PV system is relatively similar for all types of solar PV systems. More important
here—considering the impact of 1 kWh of PV-produced electricity—is the influ-
ence of the irradiation and assumed lifetime, as will be discussed below.