•
15.6
Bypass diode thermal testing to study whether overheating of these diodes causes
degradation of the encapsulant, backsheet or the junction box.
Meeting the requirements of IEC 61215/IEC 61646, however, is not a 25 year
guarantee. The actual lifetime is not only determined by the module design and the
module used, but also the climate (e.g. hot-dry or warm high-humidity) and the specific
application (e.g. integrated in a roof or free-standing). Research is ongoing to determine
which accelerated tests are required in order to guarantee a specific lifetime (e.g. 25 years)
depending on the climate and the specific application.
In addition to IEC 61215/IEC 61646 qualification and type approvals safety
qualifications according to IEC 61730 (Part 1 [110] and Part 2 [111]) are also required for
PV modules used in grid-connected PV systems and in most other applications as well.
For special applications dedicated standards are available e.g. IEC 61701 (salt-mist
corrosion testing [112]) for applications in a salty environments and IEC 62716 (ammonia
testing [113]) for applications on or near stables.
Qualification tests are carried out by independent organizations like TÜV Rheinland
in Germany.
Thin-film modules
Making thin-film modules is very different from making modules from c-Si solar cells.
While for c-Si technology producing solar cells and PV modules are two distinct steps, in
thin-film technology producing cells and modules cannot be separated from each other. To
illustrate this we look at a PV module where the thin-films are deposited in superstrate
configuration on glass, as illustrated in Figure 15.6. For making such a module, a
transparent front contact, a stack of (photo)active layers that also contain one or more
semiconductor junctions, and a metallic back contact are deposited onto each other. In
industrial production, the glass plates onto which these layers are deposited can be very
large, with sizes significantly exceeding 1 × 1 m
2
.
Such a stack of layers deposited onto a large glass plate in principle forms one very
large solar cell that will produce a very high current. Since all the current would have to be
transported across the front and back contacts, which are very thin, resistive losses in the
module are an even bigger problem than for c-Si modules. Therefore, the module is
produced such that it consists of many very narrow cells of about 1 cm width and the
length being equal to the module length. These cells then are connected in series across
the width of the module. On the very left and right of the module, metallic busbars collect
15.6
Bypass diode thermal testing to study whether overheating of these diodes causes
degradation of the encapsulant, backsheet or the junction box.
Meeting the requirements of IEC 61215/IEC 61646, however, is not a 25 year
guarantee. The actual lifetime is not only determined by the module design and the
module used, but also the climate (e.g. hot-dry or warm high-humidity) and the specific
application (e.g. integrated in a roof or free-standing). Research is ongoing to determine
which accelerated tests are required in order to guarantee a specific lifetime (e.g. 25 years)
depending on the climate and the specific application.
In addition to IEC 61215/IEC 61646 qualification and type approvals safety
qualifications according to IEC 61730 (Part 1 [110] and Part 2 [111]) are also required for
PV modules used in grid-connected PV systems and in most other applications as well.
For special applications dedicated standards are available e.g. IEC 61701 (salt-mist
corrosion testing [112]) for applications in a salty environments and IEC 62716 (ammonia
testing [113]) for applications on or near stables.
Qualification tests are carried out by independent organizations like TÜV Rheinland
in Germany.
Thin-film modules
Making thin-film modules is very different from making modules from c-Si solar cells.
While for c-Si technology producing solar cells and PV modules are two distinct steps, in
thin-film technology producing cells and modules cannot be separated from each other. To
illustrate this we look at a PV module where the thin-films are deposited in superstrate
configuration on glass, as illustrated in Figure 15.6. For making such a module, a
transparent front contact, a stack of (photo)active layers that also contain one or more
semiconductor junctions, and a metallic back contact are deposited onto each other. In
industrial production, the glass plates onto which these layers are deposited can be very
large, with sizes significantly exceeding 1 × 1 m
2
.
Such a stack of layers deposited onto a large glass plate in principle forms one very
large solar cell that will produce a very high current. Since all the current would have to be
transported across the front and back contacts, which are very thin, resistive losses in the
module are an even bigger problem than for c-Si modules. Therefore, the module is
produced such that it consists of many very narrow cells of about 1 cm width and the
length being equal to the module length. These cells then are connected in series across
the width of the module. On the very left and right of the module, metallic busbars collect