636
22 Light-to-Electricity Conversion
(a)
(b)
Fig. 22.68 a Schematic layer stacking of three-junction (3J) solar cell. The step-graded buffer (metamorphic buffer)
changes the in-plane lattice constant for the following layers. Adapted from [1917]. b Cross-section TEM image of
metamorphic InGaAs buffer on Ge. Adapted from [1918]
Fig. 22.69 Photovoltaic
module price (US$/W)
(adjusted to 2002 dollars)
vs. the cumulated
production. The dashed
line represents Swanson’s
law. Most data from
[1924]; data for 2016 and
2018 added from various
sources
the installed (cumulated) solar power (dashed line in Fig. 22.69). After 2005, a rise in silicon cost has
lead to a deviation for a few years, but recently the trend has shown even faster cost reductions.
The energy payback period is also dropping rapidly. For example, it took 2010 typical crystalline
silicon module about 4 years to generate more energy than went into making the module in the first
place. The next generation of silicon modules, employing a different grade of silicon and use thinner
layers of semiconductor material, had 2011 an energy payback of about 2 years [1926]; energy payback
time of course also depends on solar irradiation and it reduces from about 2 years in northern Europe
22 Light-to-Electricity Conversion
(a)
(b)
Fig. 22.68 a Schematic layer stacking of three-junction (3J) solar cell. The step-graded buffer (metamorphic buffer)
changes the in-plane lattice constant for the following layers. Adapted from [1917]. b Cross-section TEM image of
metamorphic InGaAs buffer on Ge. Adapted from [1918]
Fig. 22.69 Photovoltaic
module price (US$/W)
(adjusted to 2002 dollars)
vs. the cumulated
production. The dashed
line represents Swanson’s
law. Most data from
[1924]; data for 2016 and
2018 added from various
sources
the installed (cumulated) solar power (dashed line in Fig. 22.69). After 2005, a rise in silicon cost has
lead to a deviation for a few years, but recently the trend has shown even faster cost reductions.
The energy payback period is also dropping rapidly. For example, it took 2010 typical crystalline
silicon module about 4 years to generate more energy than went into making the module in the first
place. The next generation of silicon modules, employing a different grade of silicon and use thinner
layers of semiconductor material, had 2011 an energy payback of about 2 years [1926]; energy payback
time of course also depends on solar irradiation and it reduces from about 2 years in northern Europe