13.5
The record conversion efficiency of lab-scale solar CdTe solar cells is 19.6% [47] and
was obtained by GE Global Research in 2013. The open circuit voltage of this cell is
857.3 mV, the short circuit current density is 28.59 mA/cm
2 , and the FF is 80.0%. The
current record module based on CdTe technology has a conversion efficiency of 16.1% at
an area of 7,200 cm
2
.
The current cost of modules from First Solar is in the order of 0.68 to 0.70 USD/W p
and is expected to drop to 0.40 USD/W p , hence keeping the cost per W p lower than that of
modules based on crystalline silicon wafers.
An important aspect that needs to be addressed is the toxicity of cadmium. However,
insoluble Cd compounds like CdTe and CdS are much less toxic than the elementary Cd.
Nonetheless, it is very important to prevent cadmium entering into the ecosystem. It is an
important question whether CdTe modules could become a major source of Cd pollution.
As of 2014, First Solar has an installed nameplate capacity of 1.8 GW p /year[85]. With this
capacity, about 2% of the total industrial Cd consumption would be taken by First Solar.
Nevertheless, recycling schemes have been set up for installed CdTe solar modules. For
example, First Solar has a recycling scheme in which a deposit of 5 dollar cents per W p is
included to cover the cost of the recycling at the end of the module lifetime.
Maybe an even bigger challenge for the CdTe technology is the supply of tellurium.
Let us take another look at Figure 13.1 that shows the abundance of the various elements
in the Earth’s crust. Tellurium is one of the rarest stable solid elements with an abundance
of about 1 μg/kg, which is comparable to that of platinum [86]. Because of its scarcity, the
supply of Te might be the limiting step to upscaling the CdTe PV technology to future
terawatt scales. On the other hand, Te as source material has only had a few users so far.
Thus, for Te no dedicated mining has been explored so far. In addition, new supplies of
tellurium-rich ores were found in Xinju, China. In conclusion, at the moment it remains
unclear to what extent the CdTe PV technology might be limited by the supply of
tellurium.
Organic photovoltaics
So far we discussed inorganic thin-film semiconductor materials such as III-V
semiconductors, amorphous and nanocrystalline silicon, CIGS and CdTe solar cells. In
this section we will take a look at organic photovoltaics. The used absorber materials are
either conductive organic polymers or organic molecules that are based on carbon, which
may form a cyclic, acyclic, linear or mixed compound structure.
The record conversion efficiency of lab-scale solar CdTe solar cells is 19.6% [47] and
was obtained by GE Global Research in 2013. The open circuit voltage of this cell is
857.3 mV, the short circuit current density is 28.59 mA/cm
2 , and the FF is 80.0%. The
current record module based on CdTe technology has a conversion efficiency of 16.1% at
an area of 7,200 cm
2
.
The current cost of modules from First Solar is in the order of 0.68 to 0.70 USD/W p
and is expected to drop to 0.40 USD/W p , hence keeping the cost per W p lower than that of
modules based on crystalline silicon wafers.
An important aspect that needs to be addressed is the toxicity of cadmium. However,
insoluble Cd compounds like CdTe and CdS are much less toxic than the elementary Cd.
Nonetheless, it is very important to prevent cadmium entering into the ecosystem. It is an
important question whether CdTe modules could become a major source of Cd pollution.
As of 2014, First Solar has an installed nameplate capacity of 1.8 GW p /year[85]. With this
capacity, about 2% of the total industrial Cd consumption would be taken by First Solar.
Nevertheless, recycling schemes have been set up for installed CdTe solar modules. For
example, First Solar has a recycling scheme in which a deposit of 5 dollar cents per W p is
included to cover the cost of the recycling at the end of the module lifetime.
Maybe an even bigger challenge for the CdTe technology is the supply of tellurium.
Let us take another look at Figure 13.1 that shows the abundance of the various elements
in the Earth’s crust. Tellurium is one of the rarest stable solid elements with an abundance
of about 1 μg/kg, which is comparable to that of platinum [86]. Because of its scarcity, the
supply of Te might be the limiting step to upscaling the CdTe PV technology to future
terawatt scales. On the other hand, Te as source material has only had a few users so far.
Thus, for Te no dedicated mining has been explored so far. In addition, new supplies of
tellurium-rich ores were found in Xinju, China. In conclusion, at the moment it remains
unclear to what extent the CdTe PV technology might be limited by the supply of
tellurium.
Organic photovoltaics
So far we discussed inorganic thin-film semiconductor materials such as III-V
semiconductors, amorphous and nanocrystalline silicon, CIGS and CdTe solar cells. In
this section we will take a look at organic photovoltaics. The used absorber materials are
either conductive organic polymers or organic molecules that are based on carbon, which
may form a cyclic, acyclic, linear or mixed compound structure.