performance ratio, and lifetime. These assessments also deviate because of the different types of installation used, such as ground mounts, rooftops, and façades. Also, assessments still are calculated from outdated information in the literature collected from antiquated PV systems. An example of such misrepresentation of the current reality was apparent in a recent PE Magazine article wherein the author stated that electricity generation cannot “…photovoltaic be an energy source for the future because photovoltaics require more energy than they produce during their lifetime”. Statements to this effect were not uncommon in the 1970s based on some early PV prototypes. However, today’s PVs return far more energy than that embodied in the life cycle of a solar system; Fig.15 illustrates this historical trend to betterment. To resolve these inconsistencies in the estimates, the International Energy Agency (IEA) PVPS Task 12 published the Guidelines on Life Cycle Assessment of Photovoltaic “Methodology Electricity” for conducting balanced, transparent, and accurate LCAs . 143 The results, presented in Fig. 16, were obtained following these Guidelines and the associated Life Cycle Inventory (LCI) data144; they represent consensus between LCA experts from the ten Task 12 member countries. Fig. 15. EPBTs of various PV systems were reduced from about 40 yrs to 0.5 yrs from 1970 to 2010 Figure 16 the Energy payback times (EPBTs) of three major types of commercial PV modules , i.e., mono-Si, multi-Si, and cadmium telluride (CdTe). Figure 16: Energy payback times (EPBTs) of rooftop mounted PV systems for U.S- and European- production and installation under average U.S. irradiation of 1800 kWh/m2/yr (4.9 kWh/m2/day), a performance ratio of 0.75, and the module efficiencies shown above. Data adapted from de Wild Scholten (2009) and Fthenakis et al. (2009); note that module efficiencies have increased since 2009, and, correspondingly, EPBTs have decreased.
performance ratio, and lifetime. These assessments also deviate because of the different types of installation used, such as ground mounts, rooftops, and façades. Also, assessments still are calculated from outdated information in the literature collected from antiquated PV systems. An example of such misrepresentation of the current reality was apparent in a recent PE Magazine article wherein the author stated that “…photovoltaic electricity generation cannot be an energy source for the future because photovoltaics require more energy than they produce during their lifetime”. Statements to this effect were not uncommon in the 1970s based on some early PV prototypes. However, today’s PVs return far more energy than that embodied in the life cycle of a solar system; Fig.15 illustrates this historical trend to betterment. To resolve these inconsistencies in the estimates, the International Energy Agency (IEA) PVPS Task 12 published the “Methodology Guidelines on Life Cycle Assessment of Photovoltaic Electricity” for conducting balanced, transparent, and accurate LCAs . 143 The results, presented in Fig. 16, were obtained following these Guidelines and the associated Life Cycle Inventory (LCI) data144; they represent consensus between LCA experts from the ten Task 12 member countries. Fig. 15. EPBTs of various PV systems were reduced from about 40 yrs to 0.5 yrs from 1970 to 2010 Figure 16 the Energy payback times (EPBTs) of three major types of commercial PV modules , i.e., mono-Si, multi-Si, and cadmium telluride (CdTe). Figure 16: Energy payback times (EPBTs) of rooftop mounted PV systems for U.S- and European- production and installation under average U.S. irradiation of 1800 kWh/m2/yr (4.9 kWh/m2/day), a performance ratio of 0.75, and the module efficiencies shown above. Data adapted from de Wild Scholten (2009) and Fthenakis et al. (2009); note that module efficiencies have increased since 2009, and, correspondingly, EPBTs have decreased.
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