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Chapter 1
Lower risk of
Slower Longer module Lower barrier
degradation rate lifetime complete costs
module failure
Reduction of investment risks
Increase of electricity generation over module and costs and lower
lifetime maintenance costs
Reduction of electricity cost
Figure 1.10:
Mechanisms through which more stable and predictable CIGS solar cells lead to reduced electricity costs.
key factor for the stability and predictability of CIGS solar cells and modules.
This was shown in Accelerated Lifetime Tests including liquid or gaseous water, like
'damp heat' tests (exposure to 85C/85% relative humidity (RH)), in which CIGS solar
o
cells and modules often failed as is shown in chapter 2. It was therefore concluded
that CIGS solar cells and modules are very sensitive to humidity ingress. Furthermore,
sensitivity to among others temperature (shocks), electrical bias and illumination has
been observed, but the impact of these loads is not necessary detrimental. Generally,
the exact nature of the degradation mechanisms of CIGS solar cells and modules is still
unknown, while their bottleneck materials and interfaces are also not yet identified.
Since the knowledge about both the stability and predictability of CIGS PV is still lim-
ited, CIGS solar cells and modules are currently exposed to very thorough accelerated
lifetime tests. In order to optimise their stability and predictability during accelerated
lifetime tests as well as field exposure, CIGS modules are protected against water in-
gression, by the use of barrier materials. For rigid modules, glass is an excellent barri-
er material, while for flexible modules, often expensive inorganic/organic multistack
materials are selected. Although this enhances the lifetime of the CIGS modules, it
also leads to higher costs and hinders the large scale market introduction of flexible
modules. Therefore, it would be attractive to have CIGS modules which consist of CIGS
solar cells that are already stable under humidity, as well as under electrical biases,
temperature and illumination, without barrier materials. Producing these ‘intrinsical-
ly’ stable CIGS cells would contribute to lower production costs due to reduced barrier
18
Lower risk of
Slower Longer module Lower barrier
degradation rate lifetime complete costs
module failure
Reduction of investment risks
Increase of electricity generation over module and costs and lower
lifetime maintenance costs
Reduction of electricity cost
Figure 1.10:
Mechanisms through which more stable and predictable CIGS solar cells lead to reduced electricity costs.
key factor for the stability and predictability of CIGS solar cells and modules.
This was shown in Accelerated Lifetime Tests including liquid or gaseous water, like
'damp heat' tests (exposure to 85C/85% relative humidity (RH)), in which CIGS solar
o
cells and modules often failed as is shown in chapter 2. It was therefore concluded
that CIGS solar cells and modules are very sensitive to humidity ingress. Furthermore,
sensitivity to among others temperature (shocks), electrical bias and illumination has
been observed, but the impact of these loads is not necessary detrimental. Generally,
the exact nature of the degradation mechanisms of CIGS solar cells and modules is still
unknown, while their bottleneck materials and interfaces are also not yet identified.
Since the knowledge about both the stability and predictability of CIGS PV is still lim-
ited, CIGS solar cells and modules are currently exposed to very thorough accelerated
lifetime tests. In order to optimise their stability and predictability during accelerated
lifetime tests as well as field exposure, CIGS modules are protected against water in-
gression, by the use of barrier materials. For rigid modules, glass is an excellent barri-
er material, while for flexible modules, often expensive inorganic/organic multistack
materials are selected. Although this enhances the lifetime of the CIGS modules, it
also leads to higher costs and hinders the large scale market introduction of flexible
modules. Therefore, it would be attractive to have CIGS modules which consist of CIGS
solar cells that are already stable under humidity, as well as under electrical biases,
temperature and illumination, without barrier materials. Producing these ‘intrinsical-
ly’ stable CIGS cells would contribute to lower production costs due to reduced barrier
18
