244
A. Virtuani
The lifetime, degradation or occurrence of failure modes for PV modules depends
upon the severity of the climate, where the module is installed; it also depends on the
type of installation. Increased climatic stress (e.g. higher temperatures, high levels
of humidity, increased exposure to UV, etc.) may, in fact, be responsible for certain
degradation modes, which are not specifically addressed in the existing qualification
standards that explicitly refer to the general conditions encountered in temperate
climates. In a similar way, as of today, the existing IEC standards do not differentiate
between different types of installations (e.g. open-rack mounting versus building
integration)—this means (as an example) that they do not take into account the higher
operating temperatures prevailing in modules fully integrated into the envelope of a
building.
These, and other considerations, have led over time to criticism related to existing
qualification standards. However, one generally admits that these test sequences have
been quite successful in identifying and eliminating module types suffering from
large degradation rates early in their lifetime. Therefore, the existing standards have
certainly contributed to an overall more sustainable diffusion of solar electricity.
Presently, module manufacturers generally compliment the basic IEC
61215/61730 certification testing with additional testing sequences. A typical example is testing according to IEC 62804 [29] for Potential Induced degradation (PID,
see Chap. 10), to IEC 61701 [30] for salt-mist corrosion testing, and to IEC 62716
[31] for ammonia-corrosion testing.
8
To overcome these limitations, extended durability testing (based on IEC) have
been designed and proposed by several research groups and certification bodies. They
include increasing stress levels and duration (time periods and number of cycles),
multiple combined stress factors (e.g. humidity and UV or humidity and high applied
voltage), and in some cases newly designed tests (e.g. dynamic mechanical load).
It should be noted, however, that, as of today, no consensus exists among industrial
players or certification bodies on the effectiveness of such extended testing.
Manufacturers use accelerated-aging testing on modules to release warranties for
their products. Terms and conditions of warranties are always manufacturer-specific
and usually cover two different aspects:
(a) Defects in materials and/or workmanship, usually with a duration of 5–
10 years. Ten years is increasingly becoming an industry standard and should
presently be considered as a minimum requirement.
8 The salt-mist corrosion test is recommended if the modules are to be operated in coastal areas.
Similarly, the ammonia corrosion test is recommended if the modules are to be operated in rural
areas in proximity to livestock, as in farming areas.
A. Virtuani
The lifetime, degradation or occurrence of failure modes for PV modules depends
upon the severity of the climate, where the module is installed; it also depends on the
type of installation. Increased climatic stress (e.g. higher temperatures, high levels
of humidity, increased exposure to UV, etc.) may, in fact, be responsible for certain
degradation modes, which are not specifically addressed in the existing qualification
standards that explicitly refer to the general conditions encountered in temperate
climates. In a similar way, as of today, the existing IEC standards do not differentiate
between different types of installations (e.g. open-rack mounting versus building
integration)—this means (as an example) that they do not take into account the higher
operating temperatures prevailing in modules fully integrated into the envelope of a
building.
These, and other considerations, have led over time to criticism related to existing
qualification standards. However, one generally admits that these test sequences have
been quite successful in identifying and eliminating module types suffering from
large degradation rates early in their lifetime. Therefore, the existing standards have
certainly contributed to an overall more sustainable diffusion of solar electricity.
Presently, module manufacturers generally compliment the basic IEC
61215/61730 certification testing with additional testing sequences. A typical example is testing according to IEC 62804 [29] for Potential Induced degradation (PID,
see Chap. 10), to IEC 61701 [30] for salt-mist corrosion testing, and to IEC 62716
[31] for ammonia-corrosion testing.
8
To overcome these limitations, extended durability testing (based on IEC) have
been designed and proposed by several research groups and certification bodies. They
include increasing stress levels and duration (time periods and number of cycles),
multiple combined stress factors (e.g. humidity and UV or humidity and high applied
voltage), and in some cases newly designed tests (e.g. dynamic mechanical load).
It should be noted, however, that, as of today, no consensus exists among industrial
players or certification bodies on the effectiveness of such extended testing.
Manufacturers use accelerated-aging testing on modules to release warranties for
their products. Terms and conditions of warranties are always manufacturer-specific
and usually cover two different aspects:
(a) Defects in materials and/or workmanship, usually with a duration of 5–
10 years. Ten years is increasingly becoming an industry standard and should
presently be considered as a minimum requirement.
8 The salt-mist corrosion test is recommended if the modules are to be operated in coastal areas.
Similarly, the ammonia corrosion test is recommended if the modules are to be operated in rural
areas in proximity to livestock, as in farming areas.